Hibernate

B. Siva Bhargava Reddy 8099498819 [email protected] Nataraj Sir 11:00 am Batch

Persistency: The place where data can be saved permanently is called persistent store.

EX: Files, Database software

Insert, update, delete and select operations on persistent stores to manipulate data are called persistence operations. These operations are also called a CURD or CRUD or SCUD operations.

CURD:

C Create (insert)

U Update

R Read (Select)

D Delete

CRUD:

C Create (insert)

R Read (Select)

U Update

D Delete

SCUD:

S Select

CCreate

U Update

D Delete

Logic written in software application to interact with persistent store and perform persistent operations is called persistence logic.

EX: JDBC Code, Hibernate Code, I/O Stream Code and e.t.c.,

Presentation Logic: The logic that generates user interface for end user is called presentation logic. End user uses this user interface to supply inputs to application and to view results given by application. (OR)

1


To view formatted results given by application. The main logic of application that generates results based on given inputs is called business logic.

Sample Application: Read sno, sname and marks from end user (Persistence logic) calculate total and average.

tot=m1+m2+m3

avg=tot/3 business logic

Generate rank for the student based his marks avg*(business logic)

Display student details

including tot, avg rank for end user…(Presentation logic).

End user: The operator of application is end user.

Note: If there is no separate business logic then persistent logic itself acts business logic of application.

Java app----I/O Streams---------------------- Files

Java App-------JBDC, o-r mapping----------- Database Software.

Java App--------JDBC+OQL+ORDBMS-----ODB Software (Versant, Poet)

Files are good as persistent stores only in small scale applications like desktop games, mobile games e.t.c., but there are not good as persistent stores in large scale projects. Database softwares are good as persistent stores in medium, large scale organizations. EX: Banking websites e.t.c.,

Limitations of Files:

1. No security2. No query language support3. Update and delete operations are complex.4. Manipulating data with multiple conditions is complex.5. Merging and comparison.

To overcome this problem we use Database software as persistent stores.

Object Database Software: The Database software which can store software object as Database table column value is called Object Database Software.

public class marks

2


{

-------------

---------------

}

marks mk=new marks();

mk(marks class obj)

Object Database Software

Object Database softwares failed in the industry because of following reasons.

i. They store multiple values in the single Database table column as software object but storing multiple values in single Database table columns is against of normalization rule number 1.

3

m1=30

m2=50

m3=70

Student Tab(Database Tabel)

Sno sname marks

10 Siva m1=30, m2=50, m3=70

11 Bhargav

12 Reddy


ii. Generating reports from the Database table of Object Database softwares is complex

process.

Note: SQL Queries are Database dependent queries.

Java application can use either JDBC or o-r mapping concepts to develop JDBC mapping concepts and to interact with Database softwares. In small scale organizations we use files as persistent stores and use I/O Streams to develop the persistent logic.

EX: Desktop games and mobile games.

In medium scale organizations Database software is used as persistence store ad JDBC to develop the persistence logic.

EX: Office automation application.

Payroll applications

Library management application and e.t.c.,

In Large scale organizations Database software used as persistent store and use or mapping style persistent logic.

EX: Banking applications/credit card applications and e.t.c.,

Drawbacks of JDBC:

1. SQL Queries are Database software dependent queries. JDBC uses SQL Queries so JDBC persistent logic is Database software persistent.

2. Changing Database software in the middle of project development or production environment is complex process.

3. All Exceptions in JDBC programming are checked exceptions we must catch and handle those exceptions.

4. JDBC supplied Middleware services but those are not sufficient not good for industry standard projects.

5. Middleware services are security transaction JDBC connection pooling and e.t.c., to overcome all the above problems we use o-r mapping persistence logic instead of JDBC persistence logic.

6. The Parameters of PreparedStatememnt related SQL query allows only positional parameters (?) and they does not allow named parameters.

7. We can send only Serializable Java objects over the network. JDBC ResultSet object can’t be sent over the network because it is not serializable object.

4


8. In JDBC programmer have to Write more common logics along with application

specific logics in every JDBC application (Scratch level coding is required).

Q) What is o-r mapping?

A) The process of linking/mapping Java class with Database table, Java class member variables with Database table columns and making objects of that Java class representing Database table records having synchronization between them is called o-r mapping. If any modification done in Java object it reflects in row/record of Database and vice-versa.

Here the word synchronization is not related to Multithreading. To develop o-r mapping persistence logic there is no need of working with SQL queries we just need to work with Java objects that are representing Database table records and we use these objects to perform all persistent operations on the table (CURD Operations). This whole process makes or mapping persistence logic as Database software independent persistence logic.

ORM Softwares Vendors priority

EJB entity bean components SUN Microsystems (Oracle) least

Hibernate SoftTree (Red Hat) 1 (90% using)

Ibatis Apache 4

JDO (Java Data Objects) Adobe least

Top Link Oracle least

OJB (Object java Bean) Apache 3

JPA SUN Microsystem (Oracle) 2

Class student o-r mapping(XML File)

{ Student (Java class) Student_Tab(Database Table) Database

int sno; java classes sno sno table

String sname; member variables Sname Sname columns

float avg; avg avg

------------

5


------------ Methods

---------------

}

Java applications o-r mapping persistence logic

St1(Student class object)

Synchronization

Synchronization

6

Stno : 101

Sname: Janu Sonu

avg: 78.67

Stno : 102

Sname: Vijay

avg: 79.99

Sno Sname avg

101 Jani Janu 78.67

102 Vijay 79.79


The ORM software like Hibernate takes the responsibility if maintaining synchronization between Java objects and Database table records. The following are the o-r mapping(ORM) softwares.

Hibernate Def: Hibernate is open source lightweight and Java based ORM software to develop object based Database software independent o-r mapping persistence logic in Java, Jee and Java Framework software based applications.

1. When hibernate software is installed it gives its source code to programmers and moreover Hibernate is free software due to this we say Hibernate is opensource software.

2. EJB Components are heavy weight components because they need heavy weight container, server softwares for execution.

3. The resources of EJB components are EJB API dependencies. Hibernate software and Hibernate components are light weight because to execute Hibernate applications we use just JDK software, Hibernate Software and there is no need of working with the heavy weight containers, server softwares.

4. Some resources of Hibernate applications can be developed without using Hibernate API.5. We can write Hibernate logic in any kind of Java applications to make them taking with

Database Software.

Framework: Framework is special software that is built on the top of core technologies having the ability to generate the common logics of the applications dynamically while working with Framework softwares.

1. Programmer just develops application specific logics because the Framework software automatically generates the common logics of application dynamically by using core technologies internally.

2. Framework software provides abstraction layer core technologies internally generate some common logic but they never make programmer bothering or knowing about these core technologies.

EX: Hibernate, Struts, Spring.

Understanding Hibernate abstraction layer on JDBC program:

1. Register JDBC driver with DriverManager service.2. Establish connection with Database software.3. Create JDBC statement object.4. Send and execute query in Database software.5. Gather results and process the results.6. Close JBDC objects.7. Take care of Exception handling.

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8. Perform Transaction management (if necessary).

1,2,3,6,7 and 8 are common logics because they are always same in JDBC based Java applications.4,5 are application specific logics because they vary in each JDBC based application.

Hibernate based Java application:

1. Create a Session factory, session objects.2. Perform persistence operations on Database table using objects.3. Gather and process the results.4. Close session factory, session objects.

Here Hibernate software internally uses JDBC code and generates all the above discussed common logics of persistence code. In Java environments three types of Framework softwares. Those are

1. Web Framework softwares2. ORM Framework Softwares3. Java-jee Framework softwares

1. Web Framework softwares: Web Framework softwares provides abstraction layer on Servlets, JSP, Core technologies and simplifies developing of web applications.

EX: Struts, JSF, Web services, Tapstrey, Spring web MVC.

2. ORM Framework Softwares: These softwares provides abstraction layer on the core JDBC technology. Simplifies the process of developing the persistence logic in o-r mapping style.

EX: Hibernate, OJB, Ibatis, Toplink e.t.c.,

3. Java-jee Framework softwares: These softwares provides abstraction layer of Java, Jee, Core technologies, JDBC, RMI, JNDI, Servlets, JSP, JMS, Java mail, EJB e.t.c., allows to develop all kinds of Java jee applications Framework style.

EX: Spring

Features of Hibernate:

1. Light weight ORM Framework Software.2. Allows us to Database software independent persistence(o-r mapping persistence logic)3. Supports POJO and POJI model programming.

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4. Can be used along with Java, JEE, Java Framework software applications to make them

internally with ORM software.5. Gives built in JDBC Connection pool also allows to work with third party supplied and

server managed JDBC Connection pool.6. Gives built in transaction management support and also allow working with server

managed Transaction management.

Note: Hibernate gives built-in middleware service and also allowed to work with third party or server supplied middleware services.

Note: Middleware services are additional and optional services which can be applied to our application to make our application running smoothly in all sitchuations.

EX: Transaction Management, Security, JDBC Connection Pooling and e.t.c.,

7. Gives the records of the table directly in the form of Collection Framework data structures which are serializable objects by default.

8. Gives the Database software independent query language called HQL.9. Also allows using direct SQL queries to develop persistence logic.10. Throws only un checked exceptions so Exception Handling while developing Hibernate

persistence logic is optional.

Note: Even though Hibernate uses JDBC and even though JDBC code throws Checked exceptions the Hibernate software converts them to unchecked exceptions by using Exception Rethrowing concept.

public void bml()

try

{

------------- source code which may checked exception

-------------

}

Catch(SQLException se)

{

Throw new arithmetic exception();// Exception Rethrowing

}

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}

11. Allows us to develop PL/SQL procedures/ functions of Database software.12. Allows to build object based relationship one to one, one to many and e.t.c.,13. Gives annotations support in programming as alternate to XML files.

Note: Annotations are Java statements that are alternate for the XML file resources configuration and other applications

14. Also supports JPA standards of o-r mapping persistence logic development.

Note: JPA defines set of rules and guidelines that are required to develop ORM softwares due to this programmers can work with all these ORM Softwares in a common way.

15. Easy to communicate and apply.16. Supports two levels catching and buffering.

Note: Buffering in Hibernate based client application reduces the network round trips between client and server.

Application Database Software: When the Java class is taken as resource of Java technology based software application and if that class not extending, not implementing pre defined class and interface of that technology specific API then that Java class is called as POJO Class.

EX: When Java class is taken as resource of Hibernate application and if that class not extending, not implementing pre defined class or interface of Hibernate API then that class is called as POJO Class.

EXAMPLES:

class Test

{

---------

----------

}

“Test” is POJO class

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EX2:

class Test implements XYX

{

-----------

------------

--------

}

XYZ is user defined interface not extending from other interfaces.

EX3:

Class Test extends ABC

{

--------------

--------------

}

ABC is user defined class and not extending from other class.

EX4:

Class Test implements java.rmi.Remote

{

---------------

---------------

}

Test is POJO it is RMI API independent.

EX5:

Class Test extends HTTPServlet

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{

------------

-------------

}

Test is not POJO class it is servet API dependent.

EX6:

Class Test implements java.io.Serializable

{

-----------------

--------------------

}

Test is POJO class because serializable(I) is very much of Core programming concepts of Java.

JDBC, JNDI, EJB, Servlets and JSP e.t.c., are called technologies

Java.lang, java.util, java.io and their sub packages are very much part of basic Java programming .

EX:

Class Test extends Thread

{

--------------

-------------

}

Text is POJO.

EX:

Class Test extends ABC

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{

-------------

-------------

}

ABC is not a POJO

EX:

Class Test

{

Public void main()

{

--------------- // Hibrenate API used here

--------------

}

Test is POJO because Hibernate API inside the method.

EX:

Public class Test implements XYZ

{

--------------

-------------

}

Text is not POJO

POJI: When Java interface is taken as resource of certain technology based Java application and that interface is not extending from predefined interfaces of that technology specific API then that interface is called POJI.

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EX: When Java interface is taken as the resources of Hibernate application and that interface is not extending from predefined interfaces of Hibernate API then that interface is called POJI.

NOTE: The POJO and POJI model programming support that is there in Hibernate programming makes the Hibernate applications as light weight applications.

Some example POJIs:

Interface Demo

{

-----------------

------------------

}

“Demo” is POJI .

Interface Demo extends java.rmi.Remote

{

---------------

---------------

}

Demo is not POJI. Demo is RMI API dependent.

Interface Demo extends java.lang.Clonable

{

-----------------

-----------------

}

Interface Demo extends Demo1

{

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--------------------

---------------------

}

Demo1 is user defined interface not extending form other interfaces. So Demo is POJI.

Interface Demo extends XYZ

{

------------------

---------------------

}

Interface XYZ extends javax.servlet.Servlet

{

--------------

---------------

}

“XYZ” is not POJI.

Hibernate 3.6 installation: If we install Hibernate 3.6 software download the following zip file www.hibernate.org website.

Hibernate_distribution_3.6.5.Final_dist.zip

extract zip file and keep it in C drive.

When we place Hibernate persistence logic in our applications then our applications become client to Database software but not Client to Hibernate Software.

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http://www.hibernate.org/


Java application(Clint to Database)

16

Hibrnate Code Persistence

Loic


To develop Hibernate persistence logics we need to following main resources.

Hibernate cfg file(XML file)(HB file)

Hibernate mapping file(XML File) (HB file)

Hibernate persistence class(Java bean class, JDBC driver e.t.c.,-----)

Understanding Hibernate architecture:

Using Hibernate we just develop persistence logic and it can’t be used to develop other logics. So programmers always use Hibernate along with other technologies in project development with respect to the diagram client application locates Hibernate resources.

ii) Client application develops object based o-r mapping persistence logic by using the located Hibernate resources and Hibernate API.

iii) The persistence logics of Client application gives instruction to Database software.

3

Client App/Component Database Hibernate Resource Server Software

1

5

17

Database Software

Java appl/AWT Swing App

Servlet App(jsp comp/prg)

Struts APP/JSF

EJB Comp/ Swing Comp

---------------------------------------

Hibernate Persistence class(Java Bean)

Hibrnate cfg file

Hibernate Mapping File(XML)

4

Object based o-r mapping persistence logic 2

N

E

T

W

O

K


iv) The Data in Database tables will be manipulated.

v) Client application receives results from Database software in the form of objects for o-r mapping programming.

Hibernate Configuration File:

<any filename>.XML can be taken as Hibernate configuration file. If no file name is specified explicitly the Hibernate software is activated in the Client application generally looks like hibernatecfg.xml as default configuration file.

This file contains JDBC driver details, Database user name, Password details and also other details instructions using which hibernate software can establish connection between Java application and Database software.

This file carries all above said details as the values of fixed hibernate properties. This file also contains the named location of hibernate mapping file. The following are minimum entries hibernate properties of configuration file.

hibernate.connection.driver_class (for JDBC driver class)

hibernate.connection.url (For url)

hibernate.connection.username (For user name)

hibernate.connection.password (For password)

hibernate.dialet

mapping file name

The values of Hibrnate configuration file will change based on the JDBC driver, Database software and its version be utilized. We can gather all property names of Configuration file(nearly 60+) either from hibernate 3.6 home project/etc/hibernate properties file(or) from hibernate 3.6 home/ documentation/manual en-us/pdf/ hibernate-reference.pdf file related (Chapter 3)

Q) What is use of Hibernate dialect property of hibernate configuration file.

A) The values specified in this property guides hibernate software in the following ways.

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1) Assign intelligent and meaningful values: Names Hibernate software to assign intelligence sensible and meaningful default values for those hibernate properties that are not specified in configuration file. This saves the time of the programmer. More over hibernate software generates default values based on Database software.

2) Generate Correct and needed SQL queries: Helps hibernate software to generate correct and needed SQL queries internally while interacting with Database software. This process is called optimized SQL query generation.

3) The Dialect Class is Hibernate Software supplied Java class and subclass of org.hibrnate.dialect.Dialect

4) The class name changed based on Database software and its version be utilized.

EX: Oracle 9i org.hibernate.dialect.Oracle9i dialect.

Oracle 10g Oracle10g dialect

Oracle 11g Oracle any version hibernate.dialect.Oracledialect

MySQL Hibernate.dialect.MySQL 5 dialect and e.t.c.,

Refer chapter3 of pdf file for mote other Databases related dialect classes.

Note: All the above dialect classes are sub classes of org.Hibernate.dialect. In Most of the sitchuations Hibernate software automatically choose the dialect. So hibernate.dialect property is optional. But configuration is recommended.

Hibernate Persistence Class: This class is Java bean class having POJO class behavior. Objects of this class represent the records of the Database table.

1. Developers use this class while developing object based o-r mapping persistence logic. Generally this class will be taken as one per Database table.

2. Objects of this class are really responsible to develop o-r mapping persistence logic. This class is also called Hibernate POJO class or entity value class or value object class.

Hibernate Mapping file:

1. Any <filename>.xml can be taken as hibernate mapping file and this filename must be mention is configuration file.

2. There is no default name for hibernate mapping file. This file contains various o-r mapping configurations like basic o-r mapping component mapping, inheritance mapping and e.t.c.,

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3. Every mapping file contains basic o-r mapping configurations which are nothing but

mapping Java class with Database table, Java class member variable with Database table columns and e.t.c.,

4. This file guides hibernate software towards generating the internal JDBC code. In one application we can have one or more hibernate mapping files.

Client Application:

1. This can be any Java, J2EE application acting as client to Database software this application activates hibernate software by locating and reading hibernate configuration mapping files

2. This application uses Hibernate API and Hibernate POJO class (Persistence class objects) to develop objects based o-r mapping persistence logic.

3. Client application uses this o-r mapping persistence logic to incorrect with Database software and to perform CURD operations on Database tables.

Most of the Web projects will be developed based on MVC2 architecture.

M Model Layer Business logic Persistence logic.

V View Layer Presentation Logic

C Controller Layer Integration logic------/ connectivity

Integration logic is responsible to monitor and control all the operations of the applications execution. Combination of various technologies to develop MVC based architecture projects

Conclusion: Always use model layer for persistence logic.

Various possible technologies in View Layer:

HTML, XHTML, JSP, Velocity, Free Marker.

Various possible technologies in Controller Layer:

1. Servlet2. Servlet Fileter

Various web Framework softwares to develop View, Controller logics:

Struts, JDF, Web Framework, Spring MVC, Tapstrey, Cocoon, OAF(Oracle activation Framework) and e.t.c.,

Various possible technologies to develop business logic in Model Layer:

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EJB, RMI, Webservices, Java bean/class HTTP involker Hessian and Barlup, CORBA( Common Object request Broker Architecture), Spring

Various possible technologies for developing persistence Model Layer:

Hibernate, Ibatis, JDBC, OJB, TopLink, OJB, Open JPA, EJB Entiry bean, JDO e.t.c.,

The high-level architecture of the Struts, Spring and Hibernate based projects.

Presentation Layer

JSP, HTML

Control Layer

Action Servlet

Service Layer

Spring JEE Application

Persistence Layer

Spring ORM Module Hibernate

Data Layer

Database Software(Oracle)

Client applications of Hibernate maintain HB POJO calss object(Hibernate persistence class object) in there states.

i) Transient Stateii) Persistent Stateiii) Detached State

The logical memory in client application where all persistent state objects are there is called as persistence context.

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i) Transient State: 1. Does not contain identity value.2. Does not represent Database table.3. This state will be there for HB Pojo class object before entering persistence context.4. When programmer creates explicit object for HB POJO class its default state is transient.ii) Persistence State: 1. Resides inside the persistence context contains identity value represent Database table

records having synchronization.2. In Hibernate programming the total or mapping persistence logic will be written based on

this state objet.iii) Detached State: 1. When persistence context is closed or Database software is down or Database table

records is deleted then persistence state object of persistence context becomes detached state object.

2. This object contains identity value but does not represent Database table record while developing persistence logic of hibernate in our client applications we need to write two important objects. Those are

a) Hibernate SessionFactory Objectb) Hibernate SessionObject.

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Understanding SessionFactory and Sessionstate object:

The HTTP session object of servlets and JSP programming is no way related with Hibernate SessionFactory, Session object. When client application creates org.hibernate.cfg configuration then the Hibernate software will be activated when client application calls close() on SessionFactory object. Then the hibernate software will be deactivated configuration class object is required to create SessionFactory object and this SessionFactory object is required to create hibernate session object.

Q) What is the use of Hibernate SessionFactory, Session Objects? What is the difference between SessionFactory and Hibernate Session objects.

Session Factory: It will be created based on the entries of Hibernate configuration file by using org.hibernate.cfg.Configuration class object.

1. This object is generally on one per Database represents JDBC Connection pool that is there in Hibernate software based Hibernate Configuration file entries. This object also represents other resources like caches

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creates

creates

Persistence

context

rep

Ssyn

Hibernate SessionFactory object

Configuration class Object

Hibernate Session object No:101

Name:Siva

Avg:90Stu.db

sno sname avg

10 raj 70

con con

con con


2. SessionFactory object is the object of Java class that implements

org.hibernate.SessionFactory(I).3. This object is capable of creating one or more Hibernate session objects

Hibernate Session object: The SessionFactory object takes one JDBC connection object from its JDBC Connection pool and gets one JDBC statement object based on that connection object and also creates Hibernate Session object by encapsulating JDBC Connection, Statement objects.

1. In One application there can be one or more Hibernate Session objects. Hibernate Session object represent persistence context. Hibernate Session Object provides API and environment to develop object based o-r mapping persistence logic.

2. Each Hibernate Session object represents Connectivity with Database software. 3. It is mediator between Java application and Hibernate Software. That means Java

application gives instruction to Hibernate software using this Session object.

Hibernate Session Object: It means it is object of Java class that implements org.hibernate.Session(I).

Immutable: Immutable object mans modification done in the data of the objects won’t reflect in current object but will be reflected in newly created object.java.lang.String class object

Mutable: if modifications done in the current object itself then it is called Mutable Object.

All user defined Java classes and majority of predefined classes are gives as mutable classes.

String s=”hello”

s=s.contact(“how”)

String buffer sb=new StringBuffer(“hello”);

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S

hello

String class obj

Hello how

String class obj

Hello how

hb


Sb=sb.concat(“how”);

Hibrenate SessionFactory objects are immutable, Hiberate Session objects are immutable, Session objects are mutable.

Code in Client application to create Hibernate SessionFactory, Session object by activating Hibernate Software:

//Activating Hibernate Software

Configuration cfg=new Configuration() //instance factory

//locate and read method of Hibernate cfg file.

Hibernate config file.cfg=cfg.configure(“\hibernate.cfg.xml”);

cfg contains the entries placed hibernate configuration file.

//create hibernate SessionFactory object.

SessionFactory factory = cfg.buildSessionFactory

//build SessionFactory uses the hibernate configuration file entries of “cfg” object and creates one JDBC connection pool and also creates and returns Hibernate SessionFactory object representing that connection pool.

//create hibernate Session obj

Session res=factory.openSession()

Open Session(): Makes SessionFactory object to create one Session object and this Session object represent an empty persistent context by default. Since we activate hibernate software in any environment by just creating object for configuration class(Predefiend). So we can say Hibernate is light weight software.

Persistence operations in Hibernate

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Single Row operations Bulk Operations

Call various methods

On Hibernate Session obj HQL

save(-) Native SQL

persistence(-) Criteria API(OBC)

update(-)

delete(-)

load(-)

get(-,-)

save or update(-)

get(-,-)

merge(-)

and etc.,

P) Write a Hibernate application to insert record into Database table by using object based o-r mapping persistence logic.

Configuration File:It is available in C:\hibernate-distribution-3.6.5.Final\project\etc location. We have to make some modifications to this file.

//hibernate.cfg.xml

<!DOCTYPE hibernate-configuration PUBLIC

"-//Hibernate/Hibernate Configuration DTD 3.0//EN"

"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">

<hibernate-configuration>

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<session-factory>

<property name="hibernate.connection.driver_class">oracle.jdbc.driver.OracleDriver</property>

<property name="hibernate.connection.url">jdbc:oracle:thin:@localhost:1521:orcl</property>

<property name="hibernate.connection.username">scott</property>

<property name="hibernate.connection.password">tiger</property>

<property name="hibernate.dialect">org.hibernate.dialect.Oracle10gDialect</property>

<mapping resource="employee.hbm.xml"/>

</session-factory>

</hibernate-configuration>

Hibernate persistence class must be Java Bean is a Java class that contains getter and setter methods. Getter methods are there read data from Bean properties and Setter methods are there to write data to bean properties.

Mapping File:

//employee.hbm.xml

<?xml version="1.0"?>

<!DOCTYPE hibernate-mapping PUBLIC

"-//Hibernate/Hibernate Mapping DTD 3.0//EN"

"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>

<class name="Employee" table="EMPLOYEE">

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<id name="Eid" column="EID"></id>

<property name="Fname" column="FNAME" />

<property name="Lname" column="LNAME"/>

<property name="Email" column="EMAIL"/>

</class>

</hibernate-mapping>

//Employee.java

public class Employee

{

//declare Bean Properties

//Declare member variables

private int eid;

private String fname,lname,email;

//write setXxx(-) and getXxx()

public void setEid(int eid)

{

this.eid=eid;

}

public int getEid()

{

return eid;

}

public void setFname(String fname)

{

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this.fname=fname;

}

public String getFname()

{

return fname;

}

public void setLname(String lname)

{

this.lname=lname;

}

public String getLname()

{

return lname;

}

public void setEmail(String email)

{

this.email=email;

}

public String getEmail()

{

return email;

}

}

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//TestClient.java

import org.hibernate.cfg.Configuration;

import org.hibernate.SessionFactory;

import org.hibernate.Session;

import org.hibernate.Transaction;

public class TestClient

{

public static void main(String args[])

{

//Activate Hibernate Software

Configuration cfg=new Configuration();

//make hibernate software locating and reading cfg file

cfg=cfg.configure("/hibernate.cfg.xml");

//create SessionFactory obj

SessionFactory factory=cfg.buildSessionFactory();

//create HB session obj

Session ses=factory.openSession();

//write o-r mapping persistence logic

//create object for HB POJO class with data

Employee eb=new Employee();

eb.setEid(101);

eb.setFname("rakesh");

eb.setLname("rao");

eb.setEmail("123422");

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//make HB software insert record

Transaction tx=ses.beginTransaction();

ses.save(eb);

tx.commit();

//close Stream objects

ses.close();

factory.close();

}

}

//OUTPUT:

C:\hbprograms\Demo1>javac *.java

C:\hbprograms\Demo1>java TestClient

SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".

SLF4J: Defaulting to no-operation (NOP) logger implementation

SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further detail

s.

SQL> select * from employee;

EID FNAME LNAME EMAIL

---------- -------------------- -------------------- --------------------

101 rakesh rao 123422

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For Complete Program Please refer Hibernate execution \CURD\save(-) folder

List of jar files:

1. Hibernate3.jar2. Antlr 2.7.6 jar3. Commons-collectioons3.1 jar4. Dom4j – 1.6.15. Javaassist-3.12.OGA6. Jta-1.1.jar7. Slf-4j-api-1.6.18. Hibernate-jpa-2.0-api.1.0.0.Final.jar9. Ojdbc14.jarfile

Add above jar files to the class path. Environemental variable to the ext folder fo <java bean>\jre\lib\ext folder .

1)Mainjarfile(available in<hibernate-3.6>home

2-7)Dependent jar files to hibernate3.jar(Available in hibernate3.6-home\lib\required foleder)

8)Dependent jar file to hibernate3.jar(available in<hibernate3.6>home\lib\jpa folder.

Compile all above java source files and execute client application

i) Keep Database table in Oracle Database software having primary key constraint based on column.

ii) Gather certain details that is required to work Oracle thin Driver

driver class name: oracle.jdbc.driver.OralceDriver

jdbc url : jdbc:url:jdbc:oracle:thin:@<host name>:<port number>:<service id>

jar file: ojdbc14 jar(jdbc 3 spe and jdk 1.5/1.6)

ojdbc6.jar (jdbc4 and jdk1.6)(oracle 11g)

iii)Develop and save following resource.

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While developing first application of Hibrnate we can use one of the following four ways to make java tools recognizing hibernate API.

i) Copy 8+1 jar files of hibernate to java.home\jre\lib\ext folder(permanent) ii) Add the address locations of 8+1jar files of Hibernate to MyComputer environment

variables class path.iii) Perpare batch file to class path as shown below and run that batch file on every

command prompt window.iv) Add the address locations of 8+1 jar files of Hibernate in Command prompt each and

every time.

Q) What is the difference between working with class path and working with ext folder?

Class path Path1. Allows both jar files and directories2. Gives global visibility entries(visible to

multiple jdks)3. New command prompt should be open

to recognize added values.4. Points to original location of jar,

directories and uses them directly

1. Allows only jar files.2. Visible to specific jdk.

3. Not required.

4. Needs another copy of jar files.

Hibernate internally uses JDBC PreparedStatement object to send and execute generated SQL queries in Database software to see this generated SQL query as log message window use show SQL property. In hibernate configuration file as shown below.

Hibernate cfg.xml:


<session-factory>

<Property name=”connection.driver-class”>

Oracle.jdbc.driver.OralceDriver

||

||

<Property name=”show_sql”>true</property>

<mapping resource=”employee.hbm.xml”/>

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</session-factory>


The word hibernate is optional in Hibernate Configuration file peroperties.

TestClient.java:


Cfg=cfg.configure();

Makes the activated hibernate software taking hibernate.cfg.xml file of current directories as default hibernate configuration file.

Configuration cfg=new Configuration;

Cfg=cfg.configure(“/mycfg.xml);

The activated software using mycfg.xml file of current directory as hibernate configuration file.

Configurattion cfg=new Configuration();

Makes application activate hibernate software based on the jar files that are added to classpath or ext folder. But this activated software doesnot read the entries of the file.

Cfg=cfg.configure(mycfg.xml)

To read and verify hibernate configuration mapping file entries by using the xml parser. DOM4J(Document object model for java). The values red from these xml files will be stored as the data of cfg object(Configuration xml parser is a software application which can validate and process xml documents)

EX: SAX parser. Simple API for processing.

DOM Parser: Document object model.

DOM4J: Document object model for java

JDOM: Java document object model.

Hibernate gives DOM4J as its SAX parser and Tomcat, web logic servers give SAX parser its xml parser. Temporarily log messages not containing in 3.6.5 because bug is there.

SessionFactory cfg=cfg.buildSessionFactory()

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Hibernate properties stored in the cfg object to creae JDBC Connection Pool and also returns SessionFactory object representing that Connection pool.


Makes Hibernate SessionFactory object to create and return Hibernae Session Object. This Session object represents an empty persistence context.

Ses.close(): This method performs

a) Close the connection between Java application and Database software.b) Close the persistence context and makes all persistent state objects as the detached state

objects.

factory.close():

a) When this method is called cleans up the Connection pool represented by SessionFactory Object.

b) Closes other resources associated with SessionFactory object(Caches)c) Deactivates the Hibernate Software.

Note: Client application activates Hibernate software by creating object for configuration class and deactivates by calling factory.close()

What happens when ses.save(eb) is called:

1. Takes the transient state object and keeps in persistence context because of this “cb” object becomes persistence state object.

2. Identify field cfg(no) done in mapping file the identity value will be generated for “eb” obj.

3. Make Hibernate software to take “eb” obj data and to insert that data as record in Database table.

4. Makes the software to keep that “eb” object and inserted record resides in Synchronizing.

Inserting a record by persistent():


Ses.persistent(eb);

Tx.commit();

For Complete Program Please refer Hibernate execution \CURD\persist(-) folder.

Q) What is the difference between save(-) and persit(-)?

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Save() Persist()

1. Session.save() first generates the identity value then inserts the record and also returns the generated identity value.

2. Prototype of Session.save(-) is public serializable(object obj) throws HibernateException.

1. Session.persist(-) also insert the record by generating identity value.

2. Prototype is public void persist(object obj) throws HibernateException.

Due to Exception Rethrowing all exceptions become unchecked exceptions. All the Hibernate API methods like session.save() internally uses JDBC code and throws checked exceptions like SQLException. But these Checked Exceptions will be rethrown as unchecked Exceptions form the catch blocks in the form of Hibernate Exception.

public serializable save(object obj) throws HibernateException

{

---------------

----------------

//some JDBC code

}

Catch(SQLException se)

{

throw new HibernateException();

}

return idvalue;

}

Catching identity value when save(-) is called:


Integer idval=(Integer) ses.save(obj);

System.out.println(“identity value=”+idval);

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Performing update, delete, select, insert operations on the Database table records hibernate gives little bit bad performance to work with JDBC technology. Because hibernate internally using JDBC to talk with Database software. This problem is solved by using cathing fecility upto certain extent.

NOTE:

1. IDE softwares are not framework softwares because IDEs are not software technologies where as frameworks are software technologies.

2. IDE is a tool that simplifies the process of working with software technologies. 3. Framework is a high end software technology which uses low end software technologies

internally to develop the applications quickly.4. We can use IDE to develop both core and Framework software based applications.

To update the record:


Ses.update(eb);

tx.commit();

Take eb having existing value in eid member variable and new values in other variables.

Updating record with merge days:

Transaction tx=ses,beginTransaction();

Ses.merge(eb);

tx.commit();

For Complete Program Please refer Hibernate execution \CURD\ merge(-) folder.

Q) what is the difference between session.merge(-) and session.update(-)?

Session.update(-) just looks to update an existing record where as session.merge(-) updates an existing record if record is available. Ohterwise inserts new record in the Database table utilizing the data of given object.

Prototypes:

1. Public void update(Object object) throws HibernateException

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2. Public object merge(Object object) throws HibernateException

Session.update(-) updates the record of the table but does not return persistent state object representing that updated record. Where as merge(-) returns persistent state object representing the inserted record or updated record of the table.

ses.update(eb);

EmpBean eb1=(EmpBean)ses.merge(eb);

1. eb is Transient state object.2. Persistent state object representing newly inserted/updated record.

Inserting/Updating record by using session.save() or session.update(-):


ses.saveOrUpdate(eb);

tx.commit();

-----------------

void saveOrUpdate(Object object) throws HibernateException

Q) what is the difference between session.merge(-), session.saveOrUpdate(-)?

Both methods are perform insert/update operations on the Database table record but session.merge(-) returns persistent state object representing that record where as session.saveOrUpdate(-) does not return that persistent state object.

ses.saveOrUpdate(eb);

EmpBean eb1=(EmpBean)ses.merge(eb);

For complete program please refer Hibernate execution \CURD\saveOrUpdate(-) folder

To delete the record:

EmpBean eb=new EmpBean();

eb.setEid(102);


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ses.delete(eb);

tx.commit();

For Complete Program Please refer Hibernate execution \CURD\delete(-) folder.

HB POJO class object or persistent object never deletes but the object which representing record delete.

Note: POJO class objects are just actors they just play roles.

Hibernate POJO class objects are like actors representing Database table records and having the capability to play or perform insert, delete, update, select operations on the Database table records.

Delete(eb) is called eb.object will not be destroyed but the record represented by eb object in the Database table will be deleted.

When the record represented by persistent state object got destroyed then the persistent state object becomes detached state object. We can use single HB POJO class object to perform multiple operations on the Database table record like one actor playing multiple roles.


eb.setNo(101);

eb.setName(“Siva”);

eb.setLname(“reddy”);

eb.setMail([email protected]);

JDBC Hibernate1. Core technology for developing

persistence logic.2. Develops SQL queries based

persistence logic.3. Persistence logic is Database software

dependent.4. Given by SUN Microsystem.5. Internally uses streams.6. Talk with Database software directly.7. Suitable for medium scale applications.8. Lazy loading not possible when we call

session.

1. Framework to develop persistence logic2. Develops object based persistence

logic(or mapping).3. Persistence logic is Database software

independent.4. Given by SoftTree (Red Hat)5. Internally use JDBC.6. Talks with Database software by

generating JDBC code.7. Suitable for large scale applications.8. Does not support lazy loading.

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mailto:[email protected]


When we call session.save(-), session.persist(-) with transient state HB POJO class object then they insert hibernate software to insert the record when these methods are called having modified persistence state object then perform update operation on the record.

The overloaded form of session.load(-,-):

i. Public object load(class HBPOJO class, serializable id)ii. Public void load(Object HBPOJOobj, serializable id)

Example to select the record by using session.load(obj, id):


ses.load(eb,103);

System.out.println(eb.getEid());

For Complete Program Please refer Hibernate execution \CURD\load(obj,id) folder

***Note: After inserting records from Database software we have to give Commit command compulsory.

In the above code load(-,-) selects the records from the table by using the given identity value and stores that record in the given eb object. The process of converting simple value to wrapper class object is called autoboxing and reverse is called auto unboxing (introduced from jdk1.5).

EmpBean eb=(EmpBean)ses.load(EmpBean.class,109);

System.out.println(eb.getEid()+" "+eb.getFname()+" "+eb.getLname()+" "+eb.getEmail());

For Complete Program Please refer Hibernate execution \CURD\load(class,id) folder

***Note: But this method never works the records which are inserted from Oracle software directly. That means we have to insert our records through Hibernate or JDBC and retrieve them.

In the above code load(-,-) selects the record form table based on given identity value, stores that record by creating object of given HBPOJO class(EmpBean) and returns that object.

In a running Java applications we take float variable to hold float value, String object to hold String value similarly we take the object of java.lang.class hold class name or interface name. We can use class properly to generate object of java.lang.class to develop representing only class or interface.length, class are two predefined properties of Java programming. The session.load(class, id) expects java.lang.class object representing POJO class.

So we can be written like this.

40


Q) what is difference between session.load(obj,id) and session.load(class, id)

A) session.load(obj,id) selects the record from the table into given HBPOJOO class object irrespective of whether that object/record is used in further part of the application(eagar loading)

Session.load(class, id) selects the record from the table and stores into the object(HB POJO class object) only when application starts utilization of that object/record. This is called lazy loading.

Note: Cooment System.out.println() while working with both load(-,-) related examples and observe the difference in the select SQL query generation (for lazy loading, eagar loading demonstration) session.load(obj,id) expects an empty HBPOJO class object and stores the selected record into that object.

Session.load(class,id) expects HBPOJO class and it only creates object for HBPOJO class to store selected record. In standalone, small scale application where multiple layers are not there use session.load(obj,id) in medium scale applications where multiple layers are there like MVC2 architecture based web applications use session.load(class,id)

selecting record by using session.get(class,id)

EX: EmpBean eb=(EmpBean)ses.get(EmpBean.class,109);


Note: There is no session.get(obj,id).

Q) what is the difference between session.load(obj,id) session.get(obj,id)?

A) Both methods are perform eagar loading of record from Database table session.load(obj,id) throws org.hibernate.Object NotFoundException when the record is not found to select where as session.get(class, id) does not throw any exception if record is not found to select.

Q) what is difference between session.load(class, id) session.get(class,id)?

Session.load(class ,id) Session.get(class,id)1. Performs lazy loading of record from

Database table.2. Throws

Exception(ObjectNotFoundExceptipn) when record is not found to select.

1. Performs eagar loading of record form Database table.

2. Does not throw any Exception.

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3. Suitable large scale applications. 3. Suitable in small scale applications.

If Java method return type is java.lang.Object class then that method can return object of any Java class as return value. If the Java method parameter type is java.lang.Object class then we can call that method with any Java class object as argument value.

Note: java.lang.Object is the topmost class in the inheritance hierarchy of any Java class. While developing Hibernate persistence logic we can perform select operations on Database table as not transient operations.

By calling session.flush(-): We can make Hibernate software synchronizing changes done in the persistent state HBPOJO class objects to Database table records.

Usage: For example we select two records or one record or any number of records at a time then the records will display as usually. For example at the time of selecting records if we want to save changes then we go for this method in the example we selected 103 and 109 records so then output is

109 sivsh rao kir

103 sivsh rao kir2

Here kir,kir2 are two mail ids. So we have to change these things so we use flush(-) at the ending of ses.close().

So now output in Oracle software is

109 sivsh rao gir

103 sivsh rao gir2

Without using flush(-) we can’t do these things.

EX: EmpBean eb=(EmpBean)ses.get(EmpBean.class,109);


EmpBean eb1=(EmpBean)ses.get(EmpBean.class,103);

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System.out.println(eb1.getEid()+" "+eb1.getFname()+" "+eb1.getLname()+"

"+eb1.getEmail());

eb.setEmail("gir");

eb1.setEmail("gir2");

ses.flush();

ses.close();

factory.close();

For Complete Program Please refer Hibernate execution \CURD\flush(-) folder

Performs synchronization persistent state objects to table rows.

By using session.refresh(-) we can make Hibernate software reloading record into persistent state object. This is nothing but performing synchronization from table row to persistent state object.

Example code in TestClient.java:

EmpBean eb=(EmpBean)ses.get(EmpBean.class,109);


try

{

Thread.sleep(2000);

}

catch(InterruptedException ie)

{

System.err.println("hello");

}

ses.refresh(eb);

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System.out.println(eb.getEid()+" "+eb.getFname()+" "+eb.getLname()+"

"+eb.getEmail());

ses.close();

factory.close();

For Complete Program Please refer Hibernate execution\CURD\ refresh(-)folder

Mysql: Type: multiuser Database software

Version: SUN Microsyste(Oracle)

Default: 3306

To download software: www.mysql.com

www.dev.mysql.com open source Database software.

Allows to create logical Databases and also gives default logical Database(mysql,test). Logical Databases are logical particions installed Database softwares every logical Database can contain tables, uses PL/SQL procedures and functions.

If multiple projects of company are using same Database software then that Database software will be installed only once but multiple logical Databases will be created in that software for multiple software for multiple projects one per projects basis Database name=orcl,test etc.,

44

Logical Database 1 Logical Database2

Logical Database3

http://www.dev.mysql.com/

http://www.mysql.com/


(Physical Software like Oracle software , mysql softaware)

In Oralce logical Database name is nothing sid(like orcl)

Orcl Database software installation gives one default logical Database(orcl)

Mysql Database installation gives one logical Database(sid)

C;\mysql\bin\bin\mysql\bin

After installing mysql 4.x software we need to activate that software by using <Mysql_home>\winmysql

Procedure to know existing username password and modify in mysql 4.x:

Right click on traffic signal(system tray area) showmemy.Inf setup tab view and modify user, password values save modification yes reactive mysql software by using above procedure.

Procedure to create logical Database and Database table in mysql 4.x:

1. Activate mysql 4.x software2. Launch sql prompt of mysql software.

<mysql_home>\bin\mysql tool3. Create logical Database <mysql> create Database mydb;4. Create employee table having records in the logical Database mydb1.conn mydb1.5. <mysql> create table employee(eid int(5), fname vatchar(10), lname varchar(10));

Inserting values:

Insert into employee values(1010,’rajesh’,’rao’,’[email protected]’);

Note: Database name is orcl or test, Database software name is Mysql, Oralce.

Procedure to know existing username password and modify in mysql:

Right click on traffic signal(System tray area)

Show me my.Inf setup

Tab view and modify user, password values save modification yes right click activate mysql software by using above password.

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4.x setup


Procedure to create logical Database and Database table in mysql 4.x:

Step-1:

1. Activate mysql 4.x software2. Launch sql prompt of mysql software

<mysq1_home> \bin\mysqltool3. Create logical Database mysql> create database mydbl;4. Create employee table having records in the Database mydb1 conn db1;

<mysql_home>create table employee(eid int(5),fname varchar(10),lname varchar(10));

Insert into employee values:

Insert into employee values(1010,’rajesh’,’rao’,’[email protected]’);

Select * from employee

In the above environment our Database software is mysql4.x our logical Database is myDb1.

Our database name is mydb1

The Devex company supplied Type-4 driver.

Type-4 mechanism based driver for mysql is called as Connector/JDBC driver.

Mechanism:Type-4

Target Database software : mysql

Jdbc driver class: org.git.mm.mysql.Drivercom.mysql.jdbc.Driver

url: jdbc:mysql:///<logical DB> (or) jdbc:mysql:/hostname:<portnumber>/<logical DB>

1. Use this url when application and mysql Database software resides in the same machine.2. Use this url when application and mysql software resides in two different machines

Jar file that represents this JDBC driver.

Mysql-connector-java-3.0

This jar file available in dewx.com or www.dewsql.com

Procedure to make first Hibernate application interacting with mysql software:

1. Keep first application ready to use.

46

http://www.dewsql.com/


2. Keep following entries in the Hibernate configuration file.

Org.git.mm.mysql.mysqlDriver3. Compile and execute client application.

Note: in XML files Hibernate programming <!DOCTYPE> statement is mandatory

NOTE: SQL yog is suitable for developing mysql without mysql knowledge.

Q) Can we develop Hibernate application without configuration file?

A) Yes, possible but not recommended to develop.


Cfg.setProperty(“Connection.driver_class”,”oracle.jdbc.driver.OracleDriver”);

Cfg.setProperty(“hibernate.connection.url”,”jdbc:oracle:thin:@localhost:1521:orcl”)

-----------

--------

//specify the mapping file

Cfg.addFile(“employee.hbm.xml”);

//create HB SessionFactory object

SessionFactory factory =cfg.buildSessionFactory();

//create HB session obj


Limitations with above code:

i. There is no possibility to modify configure hibernate configuration values without recompiling source code.

ii. For certain properties we can’t take hibernate word in property name as optional. Some miscellaneous properties like show_sql will not work even through they are configured.

Note: It is always recommended to use Hibernate Configuration file.

For Complete Program please Hibernate execution\HibernateNotConfFile folder

47


Q) Can we develop Hibernate application without mapping file?

A) Yes, By using Hibernate annotations in the Hibernate persistence class.

Chaining:

Calling one method on the results of the another method in a class is called chaining.

EX: int len=new String(“hello how are you”).substring(2,7).concat(“123”).length();//

Output is 9.

EX2: Session ses=new configuration().configure(“/mycfg.xml”).buildSessionFactory().openSession();

We can use this method chaining concept to create Hibernate session object by having single line of code.

Note: The method which has void it is not possible to participate in method chaining.

MyEclipse: MyEclipse=EclipseIDE+built in plugin

Plug-in: Plug-in is a patch software or software application that can be used to enhance the functionalities of existing software and software application. In Java environment plugins comes as jar files. Plugins of IDE simplifies the process of working with software technologies.

Eclipse MyEclipse1. Open source2. Does not provide builtin plugins to

work with advanced technologies but allows to add plugins.

3. Suitable for small scale projects.

1. Commercial2. Provide built in plugins and allows to

add plugins externally.

3. Suitable for large scale projects.

Note: Easy Eclipse, Eclipse Galilio and etc., are alternative for MyEclipse which are developed based on Eclipse.

MyEclipse Details:

Type: IDE software fo Java Environment.

Vendor: Eclipse org

Version: 8.x(compatable with jdk 1.5,1.6)Commercial IDE.

48


For help details: www.myeclipseide.com

Gives Tomcat as default server and allows configuring other servers.

Reverse Engineering: To Generating POJO class mapping file based on Database table.

Procedure to develop first application by using MyEclipse8.X IDE:

Refer Working with MyEclipse MSWord document.

Algorithms: Hibernate software identify each HBPOJO class object through its identity value. We can make Hibernate software working with different algorithms/strategies to generate these identity values dynamically. Every algorithm is having one nick name and class name if no algorithm is configured the default algorithm is “Assigned”

Nick name Algorithm class name1. Assigned2. Increment3. Identity4. Sequence5. Helio6. UUID7. GUID8. Native9. Select10. Foreign

org.hibernate.id.AssignedGeneratororg.hibernate.id.IncrementGeneratororg.hibernate.id.IdentityGeneratororg.hibernate.id.SequenceGeneratororg.hibernate.id.TableHelioGeneratororg.hibernate.id.UUIDGeneratororg.hibernate.id.GUIDGeneratorno classorg.hibernate.id.SelectGeneratororg.hibernate.id.ForeignGenerator

i) Make sure that algorithm is compatible with underlying Database software.ii) Make sure that algorithm generated value type is compatible to store in the identity field

member variable.

Assigned Algorithm: It is default algorithm if no other algorithm is specified this algorithm can generate all types of identity values based on the type of algorithm works with all Database softwares. This algorithm uses the values set to identity field variables as identity value.

This is default algorithm that means upto now we developed all algorithms by using this one.

Increment algorithm: This algorithm uses maximum value+1 and generates identity values of type long, short or int. This algorithm works with all Database softwares.

This algorithm does not consider the deleted record values while generating identity value.

For Complete program please refer Hibernate execution\Algorithms\Increment folder

49

http://www.myeclipseide.com/


Identity algorithm: This means it take deleted value consider but it is not suitable for oracle. Only for mysql, DB2 etc.,…. This algorithm uses Maximum value+1 formula to generate identity value of type int,long,short. This algorithm works with identity columns supported by mysql,SQL server, DB2, Sybase database softwares. To work with this algorithm in mysql, the EID column if employee table must be taken as identity column by applying auto increment constraints.

Q) Difference between Increment and Decrement algorithms?

Increment Identity1. It is Database software independent

algithm.

2. Here Hibernate software directly generates identity value.

3. Does not consider deleted records while generating new identity values.

4. The identity field member variable related Database table column records need not to have any constraints.

1. This algorithm works with those Database sofwares which supports identity columns.

2. Here Hibernae software gather identity value from the identity column of Database software.

3. Consider deleted records while generating new identity values.

4. The identity filed member variable related table column must between identity column by applying auto increment constraints.

Sequence Algorithm: This algorithm uses the sequence created/generated in DB2, Postgres, Oracle, e.t.c., Database softwares can generate identity value of type of long, short, int. This algorithm does not work with MySql because MySql does not support sequences if no sequence name is specified explicitly for Hibernate software looks to use/create/Hibernate sequence contains the logic of incrementing by 1.

EX1: With user defined sequence creation

Step1: Create sequence in Oracle Database software.

SQL> create sequence seq1 start with 20 increment by 5;

Sequence created.

Step2: Configure sequence algorithm by specifying the above sequence name in

Employee.hbm.xml

EX: <hibernate-mapping>

<class name="EmpBean" table="EMPLOYEE">

50


<id name="Eid" column="EID">

<generator class="sequence">

<param name="sequence">my_seq</param>

</generator>

</id>

For Complete Program please refer Hibernate execution\Algorithms\sequence folder

EX2: Utilizing the default Hibernate sequence

Step1: Add the following property in the configuration file.

<property name="hbm2ddl.auto">update</property>

Step2: Configure sequence algorithm in mapping file.


<generator class="sequence">

<param name="sequence">my_seq</param>

</generator>

</id>

For Complete Program please refer Hibernate execution\Algorithms\UserSequence folder

Hilo: This algorithm uses hi/lo values to generate long, short, int type identity values this algorithm with all Database softwares. This algorithm uses helper table column values as the source of high value similarly max-low param value while generating the identity values. The following three are parameters of this algorithm.

i) Table To specify helper table nameii) Column To specify helper table column name(this value becomes the source of hi

value)iii) Max_lo To specify lo value.

Note: The helper table column value will be incremented by 1 for every identity value generation. This algorithm uses the following formula to generate the identity value.

hi-value*(max-lo value+1)

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The column value in helper class table.

EX: Create helper table having column with value.

SQL> create table mytab(mycol number(4));

Table created.

SQL> insert into mytab values(10);

1 row created.

SQL> commit;

Commit complete.

For Complete Program please refer Hibernate execution\Algorithms\Hilo folder

Sequence Hilo: This algorithm also uses hi.lo algorithm to generate the identity values of type int, long or short this uses Database sequence generated value as hi value and Max_lo param value as lo value. The parameters are

sequence The Database sequence name as the source of hi value.

Max_lo use the value as the source of low value.

This algorithm works with only those Database softwares which support sequences.

Step1: Create sequence in Database software

SQL> create sequence myseq1 start with 10 increment by 2;

Sequence created.

SQL> commit;

Commit complete.

Step2: Configure sequence seqhilo algorithm in mapping file.


<generator class="seqhilo">

<param name="sequence">myseq1</param>

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<param name="max_lo">5</param>

</generator>

</id>

For Complete Program Please refer D:\Frameworks\Hibernate execution\Algorithms\SequenceHilo folder

Native Algorithm: This algorithm does not have its own behavior but dynamically fix up identity or sequence or hilo algorithms depending upon the capabilities of underlying Database softwares. With Oracle Native algorithm internally uses sequence algorithm (because Oralce supports sequences) with MySql native algorithm internally uses identity. Because MySql supports identity columns. If underlying Database software does not support both sequence, identity algorithms then the native algorithm internally uses hilo algorithm. If underlying Database software supports all he three algorithms then the native algorithm uses identity algorithm internally.

Annotations: Annotations are the Java statements which can be used to perform meta data operations and resource configurations.

1. Annotations are alternate for XML files towards performing resource configuration. Data about data is called metadata.

2. Configuring resource in XML file and passing more details about that resource to the underlying executing environment is called as Metadata operations or resource configuration.

3. Configuring servlet program in web.xml file is called as resource configuration or metadata operation. From servlet 2.5 api onwards this work can be done in .java files using annotations.

Syn:@ <connection_name>(param 1=val1, param2=val2….)

There are two types of annotations in Java

i) Documentation annotationsii) Programming annotationsi) Documentation annotations: These will be used in documentation comments/*…….*/.

These are available in jdk1.1 to 1.4ii) Programming annotations: These annotations will be used for programming in Java.

These will be used as alternative for XML files for resource configuration.These are introduced from jdk 1.5

Examples for documentation annotations:

53


@author, @since, @param, @throws and e.t.c.,-----------

(refer .java files of <java_home\src.zip file)

Examples of Programming annotations:

@Override, @FailSafe and e.t.c.,

Q) What is are the differences between configuring resources using XML files and using annotations?

XML Files Annotations1. XML parsers read data from xml files.

2. XML parser is heavy weight software application so working with XML files for resources configuration

3. Gives bad performance but gives good flexibility of modification with out modifying the source code

1. Annotations are placed in .java files directly

2. Annotations are underlying runtime environment or container. So these are recognized directly by JVM.

3. Gives good performance, flexibility is not there because each and every time we have to compile .java file.

The technologies which are giving support to annotations:

Servlet 2.5, 3.X, Hibernate 3.5+, 3.X, EJB 3.X, Struts 2.X e.t.c.,

Every annotation is special @interface containing methods representing annotation parameters.

Annotations of Standalone applications will be recognized and processed by jre/JVM , Servlet alllication will be recognize by servlet container(Catalina), For EJB EJB container, For Hibernate applications Hibernate software.

We can apply annotations at three levels of Java source code.

i) Resource level/on the top of the class/on the top of the interfaceii) Method level on the top of the Java methods.iii) Field level/ on the top of the Data member.

These Annotations makes resources, methods, fields to be recognized by the container or jre as special entity.

UUID: This algorithm uses id address of current computer as base to generate identity value. This algorithm generate identity value of type string containing decimal digits. This algorithm will work with all Database softwares.

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GUID: Uses the Database generated GUID based String as identity values. This algorithm works only with SQL server.

Foreign: This algorithm uses id value of one Hibernate POJO class object as the id value of another HB POJO class object. This algorithm is useful working with 1 to 1 association.

Select: This algorithm uses Database trigger generated value as id value.

Hibernate software supplied some special built in tools to perform DDL operations on Database software those are Create table, Alter table, Drop table operations.

Note: These operations are not possible through Hibernate 3.6.5

Built-in tools of Hibernate software to perform DDL operations:

1. SchemaExport(always creates new DB table)2. SchemaUpdate(locates/create/alter Database table)3. SchemaValidator(locates/validates the Database table)

These tools performs these activities based on the configuration in mapping files, configuration files. To work with these tools the basic set up of Hibernate is enough.

SchemaExprot: Always create new Database table and also drops existing Database table if necessary. To apply constraints on the table columns we can provide instructions to this tool by using length, not null, unique and unique etc., attributes of property, id tag in mapping.

EX:

Step1: keep mapping file ready by specifying the constraints that we want to apply on Database table.

Employeee.hbm.xml:

Step2: use SchemaExport tool from command prompt and show below.

EX: java org.hibernate.tool./hbm2ddl.SchemaExport --config=hibernate1.cfg.xml (This is not working in Hibernate 3.6.5)

Note: It is also not recommended to do from Command prompt. For better result use NetBeans IDE7.1

SchemaUpdate: This tool uses the existing table if already available or modifies the existing table if needed or creates the new Database table if table is not readily available. This tool never drops existing table but alters the existing table if necessary.

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To locate/create table:

1. Keep the first application setup as it is2. Run the SchemaUpdate tool.

EX: java org.hibernate.tool./hbm2ddl.SchemaExport --config=hibernate1.cfg.xml (This is not working in Hibernate 3.6.5)

To alter table:

1. Keep the first application ready2. Add new property in EmpBean class having getter, setter method like String xyz3. Configure this new property in hibernate mapping file.4. Run the SchemaUpdate tool.

Note: These two tools are very useful to perform DDL operations in new Database software whose SQL queries are totally unaware to programmers. If Database software of project is changed to postgres SQL to Oralce then programmer need not aware of the SQL queries of Postgres SQL then he can think about using these tools to create tables in thos Postgres SQL Database software.

Ex: java org.hibernate.tool./hbm2ddl.SchemaExport --config=hibernate1.cfg.xml (This is not working in Hibernate 3.6.5)

Schema Validator: this tool checks whether Database table in Database software is there according to the configurations done in Hibernate mapping file. If not there this tool will raise the exception. This tool is not update of creating tables or dropping tables altering tables. This tool just verifies/validates Database table according to the configurations in mapping file.

EX: java org.hibernate.tool./hbm2ddl.SchemaValidate --config=hibernate1.cfg.xml (This is not working in Hibernate 3.6.5)

To see these tools execution happening dynamically along with hibernate application execution we need to work with the special property of hibernate configuration file that is

i) Create ii) Update(popular tool)iii) Validateiv) Create/frop

i) Create : Internally uses SchemaExprot tool so always creates new Database table.

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EX: <property name="hibernate.hbm2ddl.auto">create</property>

For Compete Program Please refer Hibernate execution\hbbmddl\Create folder

ii) Update(popular tool): Internally uses SchemaUpdate tool so that it can locate/create/alter Database table. This value is most regularly used value.

EX: <property name="hibernate.hbm2ddl.auto">update</property>

In mapping flle:

<property name="Fname" column="FNAME" length="25" />

<property name="Lname" column="LNAME" length="22" not-null="true"/>

<property name="Email" column="EMAIL" length="21" unique="false"/>

For Compete Program please refer Hibernate execution\hbbmddl\Update folder

iii) Validate: If we keep any value it take as default value.

This value internally uses SchemaValidator tool and always verifies whether Database table of Database software is there according to mapping file entries or not.

//Note: Schema Validate is not working in MyEclipse IDE. It is working with NetBeans IDE. It is also not working in manual process also.

OUTPUT:

INFO: columns: [lname, email, eid, fname]

Hibernate: insert into SCOTT.EMPLOYEE (FNAME, LNAME, EMAIL, EID) values (?, ?, ?, ?)

Record inserted

This is note working with MyEclipse IDE, It is only working with NetBeans IDE. It is also not working with manual process.

For complete program please refer Hibernate execution\hbbmddl\Validate folder

iv) Create/drop: This value internally uses SchemaExprot tool but creates Database table when SessionFactory object is created and drops that Database table when SessionFactory object is closed(Factroy.close) this value is useful to create and drop Database tables of the project on temporary basis towards demonstrations, testing mode of the project.

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JDBC Connection pool: JDBC Connection pool is a factory that contains set of readily available JDBC connection objects. Every Hibernate application internally contains one JDBC connection pool represented by SessionFactory object. Our Hibernate application can work with these types of JDBC Connection pools.

i) Hibernate Software supplied buit-in poolii) Third party software supplied JDBC Connection pool.iii) Server managed JDBC connection pool(web server/application server)

Because of poor performance and bad features the Hibernate supplied JDBC connection pool is not suitable for Production Environment of projects in real time applications. But we can control this pool size property as shown below. This pool default maximum capacity is 20.

Procedure to work C3P0 JDBC Connection Pool in our Hibernate applicatios:

Step1: Keep first Hibernate application ready

Step2: Add C:\hibernate-distribution-3.6.5.Final\lib\optional\c3p0\c3p0-0.9.1.jar

Step3: Add Provider_class property in Hibernate Configuration file to make Hibernate Software file to make Hibernate software working with C3P0 Connection Pool(Specify Connection Provider class) in Hibernate.cfg.xml

//Configuration File:

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">


<session-factory>

<property name="hibernate.dialect">org.hibernate.dialect.OracleDialect</property>

<property name="hibernate.connection.driver_class">oracle.jdbc.OracleDriver</property>

<property name="hibernate.connection.url">jdbc:oracle:thin:@localhost:1521:orcl</property>

<property name="hibernate.connection.username">scott</property>

<property name="hibernate.connection.password">tiger</property>

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<property name="hibernate.connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider</property>

<property name="hibernate.connection.pool_size">25</property>

<property name="hibernate.c3p0.max_size">2</property>

<property name="hibernate.c3p0.timeout">5000</property>

<property name="hibernate.c3p0.acquire_increment">2</property>

<property name="show_sql">true</property>

<mapping resource="hibernate.hbm.xml"/>

</session-factory>


For Complete program please refer D:\Frameworks\Hibernate execution\C3P0 folder

Note: If we work with NetBeans IDE we have to import C3P0 tool but in My Eclipse it is not necessary.

Note: At the time of using C3P0 connection pooling if we violate primary key, it is not giving any response and also the value not inserting. Even if there is no primary key the value is not inserting.

Q) What is the JDBC Connection pool that you have used in your project Development?

C3PO, POXOL in Standalone applications, Server managed JDBC Connection pool while working with Hibernate applications that are deployable in server.

EX: like web applications, EJB components etc.,

Based on the Connection provider class that are configure in the Hibernate configuration file. Hibernate software becomes ready to use certain JDBC connection pool while executing applications.

To configure these Connection provider classes in Hibernate cfg file we can use “hibernate.connection.provider_class” property.

Gather information Step3 or Step4 from <hibernate_home>/project/etc/hibernate properties file.

Or Chapter 3.3 of pdf file. Run the Client application.

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Procedure to use Proxool Connection in Hibernate application:

i. Keep first application ready.ii. Hibernate/lib/optional proxol/proxol-0.8.3.jar file to class path.iii. Specify the connection provider class in Hibernate configuration file to work with

proxool tool.iv. Develop separate file having the pool related JDBC prorperties.

Specify the above xml file name and its alias name in Hibernate configuration file.

Since proxol tool releated parameters are specified in separate XML file delete the related properties from configuration file(driver_class, url, user name, password and etc.,)

Run the Client application.

Note: This is not executing in NetBeans IDE, It will execute in MyEclipse IDE.

At the time of using proxool connection pooling if we violate primary key, it is not giving any response and also the value not inserting. Even if there is no primary key the value is not inserting.

For Complete Program Please refer Hibernate execution\Proxool folder.

Note: The Program may run or may not run. Most of cases it is not running.So its best always go for C3P0.

Note: It is better to go for C3P0. We have to modify one XML file no need to create another XML so execution time will become less.

Registry Software: registry software maintains object and object references having global visibility.

EX: Registry softwares.

Web logic registry built- in in web logic server. Glassfish registry built-in in Glassfish server, RMI built in jdk, COS(common object service is built in JDK, web sphere. Java applications are use JNDI API code to talking with Registry softwares. JNDI API is built-in API of jdk software(javax.naming and its sub packages). JDBC data source object represents JDBC connection pool and allows to access connection objects from the Connection pool for global visibility. This data source object will be placed in the Registry software. JDBC Data source object means it is object of the JDBC driver supplied java class that implements javax.sql.DataSource interface.

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Understanding the working environment of server managed JDBC Connection Pool:

Client Application webserver/Application server

Returns JDBC Connection object back to JDBC Connection Pool

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Gets JDBC DataSource reference from Registry

Calls

getConnection on DataSource reference and gets Connection object from JDBC Connection Pool

Uses the Connection Object to create other JDBC Connection object and to develop JDBC persistence logic.

Con.close()

JDBC DataSource obj Server Managed JDBC

Connection

Pool

(for Oracle)

Uses Type-3/4 driver

Sathya(nick name for JNDI) DataSource

10

5

6

8

2

3

7

1

4

9

8


All Common objects in Connection Pool represents connectivity with same Database software. Entire team uses single JDBC connection pool while developing the project. With respect the diagram

1,2,3) In server type-1 or 2 or 4 driver will be utilize to interact with Database software and create JDBC Connection pool having set of JDBC Connection objects. Objects in server JDBC data source object will be created having representing the Connection Pool.

4) For global visibility the DataSource object reference will be placed in Registry software.

5) Client application gets DataSource object reference from Registry by using JNDI(java naming and directory interface) code.

6,7,8) Client application calls getConenction() o DataSource object reference this call internally uses Type-3 protocol and gets one Connection object from Connection Pool from Client application.

9,10) Refer diagram

Q) What is the JDBC driver that you have used in your project?

A) Type-3 with Type-4 while working with projects that are deployable in servers to work with server managed JDBC Connection pool. Just Type-4 driver in standalone projects which run outside servers.

Q) How many Connections in JDBC?

A) Two types

1) Direct Connection using DriverManager.getConnection

EX: class.forName(“…..”)

Connection con=DriverManager.getConnection(-,-)

2) Pooled Connection using DataSource.getConnection(). It is the JDBC Connection object that is collected from JDBC Connection Pool.

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Web based Connection Pooling:

Web Logic Server:

Type: Application server

Vendor: BEA systems(Oracle)

Type of Software: Commercial software

Port number : 7001

Download: www.commerce.bea.com

Help related documents: www.edos.bea.com

Version: 8.1 jdk(out dated)

9.1-> jdk 1.5,1.6 10.0 -> jdk 1.7

Jar file: weblogic.jar

Note: weblogic9.1 supports jdk1.5,1.6 only not for 1.7

The multiple projects of Company uses multiple domains of web logic installing web logic software only once domains will be created in the software.

Client Side Server Side

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Java Application

JDBC CodeJDBC driver for Oracle

Oracle Database Software

Network

http://www.edos.bea.com/

http://www.commerce.bea.com/


Client Side ServerSide web Logic Registry

JDBC Driver is the bridge between Java application and Database software. Every JDBC driver is identified which its driver class name. Naming manager is the bridge between Java application and Registry software and every memory manager is identified with its initial context factory class name. JDBC Connection object represents the connectivity between Java application and Database software. To create this connection object we need JDBC properties like driver class name, url, Database user name, Database password. These JDBC properties will change based on the JDBC driver and Database software we use.

InitialContextObject: It represents connectivity between Java application and Registry software. To create this object we need JNDI properties will be change based on the naming manager, Registry software we use. JNDI properties are like IntialContextFactory class name provider url.

JNDI properties values of web logic registry:

IntialContextFactory class name: weblogic.jndi.WLInitialContextFactory(available in Web Logic)

Provider url : t2://<host name>:<port no>t3://localhost

Procedure to use JDBC Connection Pool for Oracle created in Web Logic server in our first Hibernate application:

1. Keep your first Hibernate application in running mode.2. Keep the Hibernate domain server of Web Logic running mode.3. Configure JDBC Connection Provider class to use server managed JDBC connection

pool in Hibernate application.

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Java Application

JDBC Code

Naming manager for Web LogicRegistry

Network


In Hibernate.cfg.xml

<property name="hibernate.connection.provider_class">org.hibernate.connection.DataSourceConnetionProvider</property>

4. Specify JNDI properties of Web Logic registration hibernate configuration file.

<property name="hibernate.jndi.class">WLInitialCotextFactory</property>

<property name="hibernate.jndi.url">t3://localhost:7001</property>

Specify JNDI name JDBC DataSource object in Hibernate configuration file.

<property name="hibernate.connection.datasource">sathya</property>

Add C:\bea\weblogic92\server\lib\weblogic.jar Web logic jar file to class path.

Remove driver_class, url, user name, Password properties related entries form Hibernate Configuration file. Run the client application the above steps based application is standalone application using the Web logic server managed Connection Pool. Which it not recommended to do.

For Complete Program Please refer D:\Frameworks\Hibernate execution\Weblogic folder

Connection PoolingGlass Fish:

Type: Application Server

Version: 3.1( Compatible with 1.6)

Vendor : Sum Microsystem(Oracle)

Registry Software: Glass Fish registry

Default Port nos: 4848 for admin console

: 8080 for accessing web applications

NetBeans IDE gives Glass Fish as built-in server we can use this Glass Fish wih or without Net Beans IDE.

To download Net Beans IDE: www.netbeans.org

Glass Fish server allows creating domains.

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http://www.netbeans.org/


Default domain is : domain1

Procedure to create user defined domain server in Glass Fish:

C:\Program Files\glassfish-3.1.1\bin>asadmin create-domain --adminport 4545

Enter the value for the domain_name operand> testuser

Enter admin user name [Enter to accept default "admin" / no password]>

Enter the admin password [Enter to accept default of no password]>

Enter the admin password again>

Using port 4545 for Admin.

Using default port 8080 for HTTP Instance.

Using default port 7676 for JMS.

Using default port 3700 for IIOP.

Using default port 8181 for HTTP_SSL.

Using default port 3820 for IIOP_SSL.

Using default port 3920 for IIOP_MUTUALAUTH.

Using default port 8686 for JMX_ADMIN.

Using default port 6666 for OSGI_SHELL.

Using default port 9009 for JAVA_DEBUGGER.

Distinguished Name of the self-signed X.509 Server Certificate is:

[CN=bhargav-ae185c5,OU=GlassFish,O=Oracle Corporation,L=Santa Clara,ST

a,C=US]

Distinguished Name of the self-signed X.509 Server Certificate is:

[CN=bhargav-ae185c5-instance,OU=GlassFish,O=Oracle Corporation,L=Santa

California,C=US]

No domain initializers found, bypassing customization step

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Domain testuser created.

Domain testuser admin port is 4545.

Domain testuser admin user is "testuser".

Command create-domain executed successfully.

Procedure to change the http port number the above domain to server:

Go to C:\Program Files\glassfish-3.1.1\glassfish\domains\domain2\config then select domain.xml file and then search for following thing

<network-listener port="8080" protocol="http-listener-1" transport="tcp" name="http-listener-1" thread-pool="http-thread-pool"></network-listener>

<network-listener port="8181" protocol="http-listener-2" transport="tcp" name="http-listener-2" thread-pool="http-thread-pool"></network-listener>

<network-listener port="4848" protocol="admin-listener" transport="tcp" name="admin-listener" thread-pool="admin-thread-pool"></network-listener>

Now change here

Procedure to open admin console of the above domain to server:

1. Start testuser server

C:\Program Files\glassfish-3.1.1\bin>asadmin start-domain testuser

Waiting for testuser to start ............................

Successfully started the domain : testuser

domain Location: C:\Program Files\glassfish-3.1.1\glassfish\domains\testuser

Log File: C:\Program Files\glassfish-3.1.1\glassfish\domains\testuser\logs\serve

r.log

Admin Port: 4545

Command start-domain executed successfully.

Open browser Type this url

http://localhost:4545

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http://localhost:4545/


Stop the server:

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C:\Program Files\glassfish-3.1.1\bin>asadmin stop-domain testuser

Waiting for the domain to stop

Command stop-domain executed successfully.

Note: User name and password of default domain

User name : domain1

Password : adminadmin

While writing hibernate persistence logic in different types of applications it is recommended to create Hibernate Session object in one time. Use that object repeatedly to execute our program.

Where we have to create Session Object in Various technologies:

Application Componet Place to create Hibernate session object

Place to use Hibernate Session object.

Servlet Program

JSP Program

AWT Frame/SWING

Applet/JApplet

Struts

JSF

Spring Application

EJB 2.X

EJB 3.X

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When we are working with web applications by using Hibernate we have to add all jar files to lib folder. Which is used by servlet container.

Procedure to transfer one record of Oracle Database table to MySql Database table.

i) Keep Employee table ready ii) Develop resource. That means write

One TestClient.java file, one EmpBean.java file, two mapping files( one for MySql another for Oracle), two Configuration files.

MyCfg.ora.xml:

Same as first application

MyCfg.mysql.xml: same as initial applications pointing to MySql.

Employee.hbm.xml: Same as first application EmpBean.java

TestClient.java:

import org.hibernate.cfg.Configuration;

import org.hibernate.SessionFactory;

import org.hibernate.Session;

import org.hibernate.Transaction;

public class TestClient1

{

public static void main(String args[])

{

Session orases=new Configuration().configure(“/mycfg-ora.xml”).buildSessionFactory().openSession();

Session mysqlses=new Configuration().configure(“/mycfg-mysql.xml”);

buildSessionFactory.openSession();

//select a record from oracle Database

EmpBean eb=(EmpBean) orases..get(EmpBean.class,675);

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System.out.println(eb.getNo+” “+eb.getFame()+” “+eb.getLname()+” “+eb.getEmail());

//insert this record into mysql

Transaction tx=mysqlses.beginTransation();

Mysqlses.save(eb);

Tx.commit();

System.out.println(“Record has been inserted successfully”);

//close HB obj

Mysqlses.close();

Orases.close();

}

}

Make sure that following jar files added to the class path. Eight Hibernate regular jar files one ojdbc14.jar one mysql-connector-3.0.8-stable.bin jar file. Compile all the .java resources and execute the TestClient applications get(-,-), ses.load(obj, id) methods directly return the persistent state HBPOJO class object representing the record that is selected where as ses.load(class,id) first returns proxy object and convert that proxy object once then record is loaded into the object.

Servlet to Database communication by using Hibernate Persistence logic:

Jar files to classpath: servlet-api.jar, Hibrnate3.jar

Jar files in <WEB-INF>/lib:

Eight regular jar files.

Q) What is the Proxy object?

A) The object that represents temporarily presence of the real persistent state object is called proxy object. Proxy object doesn’t represent record and does not contain data and creates new persistent state object once record is loaded from database.

HQL:

1. HQL means Hibernate Query language. These queries are Database software independent queries.

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2. Hibernate software converts HQL queries into underlying Database software specific

HQL queries by using AST translator.3. HQL Query based persistence logic is Database software independent.4. HQL queries will be written based on HB POJO class and its member variables.5. HQL Supports both named and positional parameters.6. HQL supports aggregate functions, operators, conditional classes sub queries, joins and

non select operations.7. HQL query will be represented with Query object(Object of a java class that implements

org.hibernate.QueryInterface.8. HQL queries are not case sensitive but class names and variable names used in these

queries are case sensitive.

Limitations:

1. In Process of converting HQL queries to SQL queries performance will be degraded.2. Using HQL queries PL/SQL programming is not possible.

SQL and HQL queries:

SQL> select * from employee;

HQL> from EmpBean(HB POJO class)

HQL> from EmpBean as e (e is alias name)

(or)

HQL> select eb from EmpBean as eb

(or)

HQL> from EmpBean

Note: as is optional every time.

SQL> select * from employee where fname like ‘S%’

HQL> select eb from EmpBean where eb.fname like ‘S%’

HQL> from EmpBean eb where eb.fname like ‘S%’

SQL> select fname, lname from employee

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HQL> select eb.fname, eb.lname from EmpBean eb;

SQL> delete from employee where eid>=100 and eid<=200

HQL> delete from EmpBean as eb where eb.no<=200

If we want to frame HQL query by specifying member variable names representing columns for framing conditions on other operation specifying alias name for HB POJO class in the query is mandatory. Otherwise opetional.

HQL queries are two types those are

1. Select Queries2. Non Select Queries (use executeUpdate() to execute these queries)

Example of executing HQL query

For example applications please refer C:\Hibernate\HQL folder.

1. Keep first application setup ready.2. Develop another client application having hibernate persistence logic.

JDBC level select query execution gives JDBC ResultSet object but this ResultSet object is not a serializable object to send over the network. So we need to write some additional logic to move the records of ResultSet to ArrayList object and to send to the ArrayList object over the network. HQL select query of Hibernate gives collection Framework list DataStructure so it can be send directly over network.

Note: All the collection Framework Data structures are Serializable objects by default.

Executing the HQL select Query using iterate():

//prepare query by pointing HQL query.

Query q1=ses.createQuery(“select eb from EmpBean eb);

Iterator ir=q1.iterate();

//makes Hibernate software to execute HQL query.

//process the results.

While(it.hasNext())

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{

EmpBean eb=(EmpBean) it.next();

System.out.println(eb.getEid()+” “+eb.getFname()+” “+eb.getLname()+” “+eb.getEmail());

}

System.out.println(“it obj class name is “+it.getClass());

Res.close();

}

}

Q) What is the difference between HQL and select query by using list() and iterate()?

A)

list() Iterate()1. Select required records at a time.

2. Generates single SQL select query.

3. Performs immediate initialization of objects with selected records selected table(indicates eagar loading)

4. EX: select four records from the table which generates single SQL select query.

5. Gives good performance

1. Select required records of the table one after another.

2. Generates multiple SQL select queries in these multiple queries first select query just returns identity values of the record and remaining queries return the records.

3. Performing on demand initialization of objects with records(indicates lazy loading)

4. EX: To select four records from the table it generates four SQL select queries.

5. Gives bad performance.

When list() is used all required records based on the given condition will be selected from the table at once by generating single select query. When iterate() is used first generated select query returns identity values of required records next generated select queries uses the identity values as condition values and selects one record at a time from the table.

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For Complete programs please refer C:\Hibernate\HQL folder

Note: HQL, EJB-QL, JPA-QL are object based query languages to develop the Database independent queries.

HQL Parameters: HQL supports two types of parameters those are

i) Positional Parametersii) Named Parameters

Executing the HQL query with positional parameters:

Query q1=ses.createQuery("select eb from Employee eb where eid>? and eid<?");

//setting values to parameters

int a=100;

int b=200;

Integer a1=new Integer(a); //Object type casting

Integer b1=new Integer(b);

q1.setInteger(0,a1);

q1.setInteger(1,b1);

List l=q1.list();//make Hibernate Software to execute HQL query

//process the List DataSource

for(int i=0;i<l.size();i++)

{

ps.Employee eb=(ps.Employee)l.get(i);


System.out.println("object class name is "+l.getClass());

}

ses.close();

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String based operation:

Query q1=ses.createQuery("select eb from Employee eb where eid>? and fname like ?");


int a=100;

String b="M%";


String b1=new String(b);


q1.setString(1,b1);




{




}

Named Positional Parameters: When multiple parameters positional parameters are there then there is a possibility of doing mistakes to identify the parameters through their indexes to overcome this problem we can work with named parameters(:<name>)

Query q1=ses.createQuery("select eb from Employee eb where eb.eid>:P1 and eb.email like :P2");


int a=3;

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String b="x%";



q1.setInteger("P1",a1);

q1.setString("P2",b1);




{



}

Note: We can prepare HQL Query by having both positional and named parameters but we can’t define/place positional parameter after any named parameter have been defined/placed.

Positional Parameter before placing the Named Parameter.

Query q1=ses.createQuery("select eb from Employee eb where eb.eid> ? and eb.email like :P2");


int a=3;

String b="x%";




q1.setString("P2",b1);

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{



}

Invalid HQL query:

Because of we shouldn’t write query like this because after named parameters we should not take named parameters in HQL query can be representing input values and conditional values. But these parameters can’t be taken representing HQL keywords POJO classes and POJO class member variables.

Query q1=ses.createQuery("select eb from Employee eb where eb.eid> :P1 and eb.email like ?");

HQL Select query with aggregate functions:

Query q1=ses.createQuery("select count(*) from Employee");

List l=q1.list();

Long l1=(Long)l.get(0);

long cnt=l1.longValue()

System.out.println("Cont of records"+cnt);

ses.close();

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//for complete program refer page no 50and Projects folder HQLTest project open AggregateFunction

List Data structure

HQL select query with multiple aggregate functions: Collection Framework data structure allow objects as elements values arrays are objects in Java. So arrays can be placed as element values of collection Framework data structures. The java.lang.Object class obj array can hold any Java class object as element values and this array itselt can become element

List Data Structure(i)

values of Collection Framework data structures. If we want to class name of certain dynamic object call getClass() on that object.

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Java.lang.long class object

Java.lang.Object.class.obj[]

0 1 2 3 4

Long Object Integer Object Integer Object Long Object Double


Executing HQL select query with multiple aggregate functions:

Query q1=ses.createQuery("select count(*),max(eb.eid),min(eb.eid),sum(eb.eid),avg(eb.eid) from Employee eb");

List l=q1.list();

Object result[]=(Object[])l.get(0);

Long res1=(Long)result[0];

long count=res1.longValue();


long max=res2.longValue();


long min=res3.longValue();


long sum=res4.longValue();

Double res5=(Double)result[4];

double avg=res4.doubleValue();

System.out.println("Number of records"+count);

System.out.println("Maximum of records"+max);

System.out.println("Minimum of records"+min);

System.out.println("Sum of records"+sum);

System.out.println(" Average of records"+avg);

ses.close();

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SubQuery: Query inside the query is called as sub query generally the results of sub query will be used as the input values of outer query.

EX:

Query q1=ses.createQuery("from Employee eb where eb.eid=(select max(eb.eid) from Employee eb)");

List l=q1.list();


{

Employee eb=(Employee)l.get(i);


}

Getting each record from Table:

By using List

Query q1=ses.createQuery("select eb.fname,eb.lname from Employee eb where eb.eid>=?");

//set param values

q1.setInteger(0,10);

//execute HQL queries

List l=q1.list();

//process the results


{

//access each element of the list

Object row[]=(Object[])l.get(i);

//process the elements of the list

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for(int k=0;k<row.length;k++)

{

System.out.println(row[k].toString()+" "); //prints each record

}

System.out.println();

}

When HQL select queries are there selecting specific column values from the Database table then the returned list data structure contains java.lang.Obejct class Object[] as element values.

Executing above example based query with iterate():

By using iterate():

Query q1=ses.createQuery("select eb.fname,eb.lname from Employee eb where eb.eid>=?");

//set param values


//execute HQL queries

Iterator itr=q1.iterate();

//process the results

while(itr.hasNext())

{


Object row[]=(Object[])itr.next();



{


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}


}

When iterate() is used to execute HQL select query that select specific column values of table it is same as List() that means on demand initialization, lazy loading multiple select SQL queries generation will not take place in this condition.

HQL non select queries can be prepared having named, positional parameters these queries must be executed as transactional statements from our applications.

Update by using named Parameters:

Query q1=ses.createQuery("update Employee eb set eb.email='[email protected]' where eb.eid=:p1");

q1.setInteger("p1",10);


int result=q1.executeUpdate();

System.out.println("number of records affected"+result);

tx.commit();

ses.close();

Writing HQL insert Query: HQL insert query is not given to insert the record into table with direct values it is given to insert the record into table by selecting the record from another table.

Wrong HQL insert Query: insert into employee eb values(?,?,?)

i) HQL insert query is not given as insert into values ………….. form. It is given as select from ….

ii) To insert single record with direct values use ses.save() or ses.persist methods.

Example application to perform HQL insert query execution:

1. Create two tables in Oracle Employee and Employee1

Employee Same as first application

Employee1 same as Employee

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Create two POJO classes Employee.java, same as first Employee1.java as first application

2. Create one mapping file configuring both Employee, Employee1 classes.3. Develop single hb configuration(hibernate.cfg.xml)4. Develop the client application

HQL insert query is not there to insert single record with direct values it is there to insert bulk records by gathering them from another table.

The HQL query that placed in Hibernate mapping file having logical name is called as named HQL queries

Advantages:

1. HQL queries become globally visible queries in the multiple applications of Hibernate environment

2. HQL queries can be used multiple session objects of Hibernate based client applications.3. HQL queries give flexibility to programmers to modify HQL queries without disturbing

the Java source code.

Limitations with following code:

Here HQL query is specific to one Hibernate Session object and it does not give global visibility and flexibility of modification.

Example on named HQL Query:

1. Keep the first application setup ready2. Place HQL query in Hibernate mapping file having logical name(as named as HQL

query)

Note: In one mapping file we can place number of HQL queries.

3. Write a logical client application to get access to named HQL query and to execute that query by using multiple Session objects

&lt: and &gt: and etc., are called entities of XML these are given to generate special symbols.

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Note: Be careful while typing Named queries in Hibernate mapping file having the utilization of less that symbol. Because this less than symbol takes XML meaning (as beginner of sub tag) to suppress this meaning and to treat it as a conditional operator we can use either entity &lt: or

Pagination : The multiple Database records of table in mapping pages by page format is called Pagination. HQL queries support pagination for that we need to use setFirstResults(-), setMaxResults methods of org.hibernate.Query interface.

For complete program please refer Hibernate\Pagination folder

Procedure to develop custom algorithm which generates identity value in following notation:

FF001

FF002

‘

‘

‘

FF003

1. After the eid column data type to varchar2(10)2. Create sequence in Oracle shown below3. Create sequence1 increment by 1.4. Keep first application ready.5. Change number property data type to String in Employee.java (also change getSno,

setSno)6. Copy SequenceGenerator.java file to first application folder from

Hibernate/project/src/main/java/org/hibernate/id folderRename the file name to FFGenerator.javaRename the class name to FFGenerator

7. Do following modification in FFGenerator.java with respect to SequenceGenerator.java file

a) Import following package import org.hiberate.id.*;b) Write following code inside the definition of generate()

Refer line number 104-106

Public searializable generate(SessionImplementation session, Object obj)

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{

return generateFolder(Session);

}

Make sure that following code is there in definition of generateHolder(-)

i) Change return type of the method2 String ii) Make sure that following code is placed in the third try block8. Configure above algorithm in Hibernate mapping file.

9) Develop and execute the client application having the logic to insert the record.

Native SQL: IF certain persistence operations are not possible with HQL queries, HQL queries are complex to write then the Database software development Native SQL queries to develop Hibernate persistence logic.

For All Native SQL program please refer Hibernate execution\NativeSQL\NamedNativeScalar folder

1. Native SQL queries are Database software dependent SQL queries.2. Native SQL queries based persistence logic is Database software dependent.3. Supports both select and non select operations.4. Supports DDL operations.5. Allows us to call PL/SQL procedures and functions.6. Allows us to place both Named and Positional parameters.7. SQL query object represents native SQL queries.

Note: SQL query object means it is the object of a Java class org.hibernate.SQLQuery interface and this interface is the sub interface of Query interface.

1. Native SQL results must be mapped with Hibernate Datatypes or HBPOJO classes receives the results through objects.

2. Hibernate Data types are the bridge data types between Java datatypes and JDBC data types.

Java type Hibernate JDBC1. int2. long3. String4. Double

Hibernate.INTEGERHibernate.LONGHibernate.STRINGHibernate.DOUBLE

Types.INTEGERTypes.LONGTyes.VARCHARTypes.DOUBLE

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3. HQL queries written based on the POJO classes and its member variables. Native SQL queries will be written based on Database table and Database table columns.

4. There are two types of Native SQL Select queries.i) Entity Queries(selects all the column values of Database table)(Results must be mapped

with HB POJO class)ii) Scalar queries (Selects specific column values of Database tables) results must be

mapped with Hibernate Data types.

EX: select * from employee

EX: select lname, fname from emp; e.t.c.,

Example application on an entity native SQL query execution:

1. Keep the setup of first application.2. Develop the client application as shown below having topic of Native SQL query.

SQLQuery q1=ses.createSQLQuery("select * from Employee");

//make result with HB POJO Class

q1.addEntity(Employee.class);

//execute native SQL Query

List l=q1.list();


{

Employee eb=(Employee)l.get(i);



}

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Note: We can’t iterate() to execute native SQL select queries when used java.lang,UnSupportedException will be raised.

Executing Scalar Query:

In Employee.hbm.xml

<sql-query name="test1">

<return alias="test1" class="Employee"/>

SELECT * from Employee WHERE eid>=?

</sql-query>

In TestClient.java

SQLQuery q1=ses.createSQLQuery("select fname,email from Employee");

//map Results with Hibernate Data types

q1.addScalar("fname", Hibernate.STRING);

q1.addScalar("email",Hibernate.STRING);

List l=q1.list();


{


Object row[]=(Object[])l.get(i);



{


}


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}

StandardBasicMappingTypeSTRING:

Note: Mapping scalar query results with Hibernate data types is opetional. Executing Native SQL scalar query having aggregate functions.

Q) Why iterate(-) is not applicable on native SQL queries and why it is applicable on HQL queries?

A) when iterate(-) is used on HQL query the Hibernate software generates multiple select queries based on Single HQL query but this kind of multiple queries generation is not possible while working with native SQL query because of this Hibernate software sends and execute native SQL query in its database software without any modifications and conversions. Due to these reasons iterate(-) is not applicable on native SQL queries.

Executing named native SQL non-select Query:

1. Place query in mapping File.

<sql-query name="test1">

insert into Employee values(?,?,?,?)

</sql-query>

2. Access the query in the client applications and execute the query

//get access to Named Native SQL query

Query q1=ses.getNamedQuery("test1");


q1.setString(1,"Tamanna");

q1.setString(2,"Bhatia");

q1.setString(3,"[email protected]");


int result=q1.executeUpdate();

System.out.println("number of records affected"+result);

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Note: If we want to place hibernate.autocommit property in configuration file then we can execute non select native SQL queries without transaction management code. Since this feature is varying Database software to Database software. It is recommended to ignore feature.

We can perform DDL operations on Database using Native SQL queries but we can’t pass the input table names and column names as parameter values that means they must be hard coded directly in the query.

We can perform even pagination on the results given by native SQL queries.

Calling values from PL/SQL stored procedures and functions: Persistence logics are centralized, reusable or globally accessible logics for multiple applications of module or for multiple modules for a project then it is recommended to develop these persistence logics in Database software as PL/SQL procedures and functions.

1. When authentication logic is required in every module instead of writing the authentication logic in every module it is recommended to centralized that logic by keeping Database software only once as PL/SQL function or procedure.

2. In JDBC we use callable statement object to call PL/SQL procedure or function. Hibernate 3 allows us to call PL/SQL procedure or function but procedure or function must be developed as a required for Hibernate software for this we need to follow list of rules. These rules will vary based on the Database software we use.

3. Cursor in Oracle is a variable that can hold set of records given by SQL select query execution. The cursor of Oracle PL/SQL programming is same as the ResultSet object of JDBC programming.

4. Oracle gives SYS_REF cursor as built-in default cursor type while developing PL/SQL procedure or function in Oracle for hibernate we must work with cursors.

5. While developing SQL procedure or function in Database software for Hibernate we need to follow set of common rules and set of Database software specific rules.

6. The common rules are i) Pagination is not possible on the results of PL/SQL procedures and functions(we

can’t use setFirstResult(-), setMaxResult(-))ii) Standard Syntax(SQL92) should be used to call PL/SQL procedure or function.

To call procedure:

{call <procedure-name>(?,?,?-----)}

To call function:

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{?=call<(function-name(?,?,?---)}

Oracle software specific rules:

PL/SQL procedure must have first parameter as OUT parameter having type (sys-ref cursor)

(or)

PL/SQL function must return a cursor (of type sys-ref cursor)

Machine2

Q) Difference between Remote and Local Client?

A) If an application and its client reside in same JVM then that client is called as local Client to Client application. If application and its Client resides in two different JVMs of same or two different JVMs of same or two different computers then the client is called as Remote Client.

Limitations and Drawbacks of Hibernate:

1. Hibernate is not distributed technology. So its persistence logic can’t be accessed from remote Client(that means allow only local clients)

2. Hibernate internally generates JDBC code. This process degrades the performance.3. Calling PL/SQL procedures and functions is very complex in Hibernate (Procedures and

functions can’t be developed freely)4. Pagination is not possible on the results generated by PL/SQL procedures and functions.5. Hibernate does not support nested, distributed transactions.6. Hibernate criteria API does not support non select transactions.7. Lazy loading or on demand initialization is not possible with native SQL queries and etc.,

EJB, Spring JEE module technologies are distributed technologies. So those applications allows both remote and local clients.

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JVM

JVM2

JVM

Application LocalClient

Remote Client

Remote Client


Criteria API (working with org.hiebrnate.criterian): Criteria means condition. Which allows to develop the entire persistence logic by using Java statements(no queries) using classes and methods.

1. Criteria API persistence logic is Database independent logic.2. Gives good performance compare to HQL.

Limitations:

1. We can’t use Criteria API to select specific columns of a table.2. We can’t use Criteria API for non-select operations.3. Working with Criteria API is complex process.4. Criteria Object represents the Criteria API persistence logic. Criteria object means it is

the object of Java class that implements org.hibernate.Crieteria interface.5. To create object for this we use Session.criteria(-).

Example application on Criteria API:

1. Keep setup of first application ready2. Take separate client application and write following logic as the Criteria API based

persistence logic.

We can use various static methods of org.hibernate.Crieterian Restrictions, Expression class to frame conditions required for the Criteria API based persistence logic. Each condition will be represented criteria object. Entire API persistence logic will be developed based on HB POJO class member variables.

Executing Criteria API logic with Condition:

Note: Criteria API with Conditions are not working with hibernate 3.6.5. But these are working with hibernate 3.2.5 in Net Beans, My Eclipse IDEs.

For complete programa please refer Hibernate execution\NetBeans Projects (This folder will open with Net Beans 7.1 or higher versions automatically)

Q) what is the difference between Criteria object and Criterian Object?

A) Criteria object represents the whole hibernate criteria API based persistence logic . In that Criterian object represent one condition. Criteria Object means it is the object of a class that implements org.hibernate.Criteria interface. To create this object we use Session.createCrieteria(-). Criteria object means it is the object of a class that implements

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org.hibernate.crieteria.Criterian interface. To create this object we use methods of Restriction class.

When multiple conditions are added Criterian API by default they will be execute with And class.

If we feel framing conditions through Java methods is very complex then we can use expression to frame those conditions as SQL statements.

Expression.sql(-): It is depreciated from Hibernate 3.5 onwards and Restrictions.sqlRestriction(-) has been given as an alternative

Criteria ct=ses.createCriteria(EmpBean.class);

Criteria cond=Restrictoins.sqlRestriction(“email like ‘%.com’”);

ct.add(cond);

List l=st.list();

for(-)

{

----

}

Versioning: Hibernate is capable of keeping the number of modifications done in records through versioning. For this we need to maintain special co column in Database and special property in Hibernate mapping file, POJO class. The feature helps banking applications how many times the address or balance of Account holder has been changed during his yearly transactions or monthly transactions that depends.

For Complete program please refer Hibernate execution\Versioning folder

Note: The versioning feature of Hibernate does not keep track of modifications if records are modified directly without selecting them into application.

Note: If modifications will happen in Database side without using hibernate those modifications never reflet.

Working with Files (Large Objects): Working with File is nothing but working with large objects there are two types of large objects.

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Large Objects

BLOB CLOB

All major Database softwares giving support for BLOB, CLOB data types.

Hibernate supports BLOB and CLOB objects based programming. While developing matrimony, JOB potal, Pay roll and etc., applications we need to insert and retrieve document, image files by taking the support of BLOB, CLOB data types.

For Complete Program Please refer D:\Frameworks\Hibernate execution\LargeObjects folder

Tip: Keep LargeObjects.java file in a package. We can retrieve any where whether we would like to use it.

Hibernate Filters: Hibernate Filters allows us to place conditions in mapping file having global visibility. Hibernate Filter global, named, parameterized filter that can be enabled or disabled for a particular Hibernate session. The condition of Hibernate Filter can be used on multiple Hibernate Session objects having abilility to enable or disable filter

Procedure to develop Hibernate application having the utilization of Filters:

i. Keep first application ready.ii. Define Filter having logical name and link that Filter with Hibernate POJO class

specifying mapping file.

In Mapping File:

1. Hibernate Filters are no way related to Servlet Filters. 2. If we need certain complex condition like getting tenth highest salary of Employee details

at that time multiple client applications are in multiple places of single client application then instead of writing along with the query every time it is recommended to write only for one time as Hibernate Filter condition in mapping file as shown above.

3. We can apply Hibernate Filters on the persistence logics of HQL Criteria API logics but can’t apply on persistence logics of Native SQL.

For complete program please refer Hibernate execution\Filters folder

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Hibernate

Documents

large scale

domain testuser

small scale

document object

domain executed

launch sql

program filesglassfish

technology