Spring Data Access

Spring Data Access

By,Srinivas Reddy.S

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Introduction to Spring JDBC

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Multiple ways to connect to DB

• JDBC• IBATIS• Hibernate• JPA• JCA

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Layered architecture

client DB

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DAO – Advantages and Best practices

Advantages:• Application is independent of the Data access

techniques and database dependency.• Offers loose coupling with the other layers of

application.• Allows to unit test the service layer using

mock objects with out connecting to database.

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DAO LayerService Layer

DAO Interfaces

DAO Implementations

DB

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DAO – Advantages and Best practices

Best practices to be followed:• Always DAO classes should adhere to

interfaces.• Interfaces should expose the functionality that

are needed by the Service layers.• Keep the database related configurations

outside the code as configurable items in an xml or properties file.

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Problems with JDBC

• Poor Exception hierarchy– SQLException– DataTruncation– SQLWarning– BatchUpdateException

Issues with JDBC Exceptions:Least explantiveDefined as checked exceptions which mandate us to write the catch blocks

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Spring Exception hirerarchy CannotAcquireLockException CannotSerializeTransactionException CleanupFailureDataAccessException ConcurrencyFailureException DataAccessException DataAccessResourceFailureException DataIntegrityViolationException DataRetrievalFailureException DeadlockLoserDataAccessException

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Spring Exception hirerarchy EmptyResultDataAccessException IncorrectResultSizeDataAccessExceptionIncorrectUpdateSemanticsDataAccessException InvalidDataAccessApiUsageException InvalidDataAccessResourceUsageException OptimisticLockingFailureException PermissionDeniedDataAccessException PessimisticLockingFailureException TypeMismatchDataAccessException UncategorizedDataAccessException

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Spring Exception Hierarchy - Advantages

• More elaborate and detailed exceptions• Exceptions not specific to an API. Can be used

with any ORM and data access API.• Declared as unchecked exceptions – No catch

blocks needed.

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Problems with JDBC – Data access• Create a connection• Create a statement• Start the transaction• Execute the statement• Iterate the result set and get the values• Commit the transaction/roll back when

exception occurs• Close the statement• Close the connection

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Spring JDBC – Template pattern

• Defines the skeleton of an algorithm in an operation, deferring some steps to subclasses.

• Template Method lets subclasses redefine certain steps of an algorithm without letting them to change the algorithms structure.

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Data access templates in Spring

• JdbcTemplate• NamedParameterJdbcTemplate• SimpleJdbcTemplate• HibernateTemplate• JpaTemplate• SqlMapClientTemplate• JdoTemplate• CciTemplate

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JDBCTemplate Dependencies

Data source

JDBCTemplat

e

DAOImpl

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Spring JDBC Configuration steps

1. Choose a data source type:1. Data sources by JDBC API.• DriverManagerDataSource• SingleConnectionDataSource

2. Data sources looked up by JNDI.• <jee:jndi-lookup id="dataSource"

jndi-name="/jdbc/springjdbc" resource-ref="true" />

3. Data sources that pool connections.– Using Apache commons DBCP– org.apache.commons.dbcp.BasicDataSource

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Spring JDBC Configuration steps

2. Configure the Data Source<bean id ="dataSource" class

="org.springframework.jdbc.datasource.DriverManagerDataSource"><property name ="driverClassName" value ="com.mysql.jdbc.Driver"/><property name ="url" value ="jdbc:mysql://localhost:3306/springjdbc"/><property name ="username" value ="root"/><property name ="password" value ="srinureddy"/></bean>

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Spring JDBC Configuration steps

3. Configure the JdbcTemplate and add data source as dependency

<bean id ="jdbcTemplate" class ="org.springframework.jdbc.core.JdbcTemplate">

<property name ="dataSource" ref ="dataSource"/></bean>

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Spring JDBC Configuration steps

• Register the Dao Impl class and add the JdbcTemplate as Dependency

<bean id ="employeeDao" class ="EmployeeDaoImpl"><property name ="jdbcTemplate" ref ="jdbcTemplate"/></bean>

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JDBCTemplate Dependencies

Data source

JDBCTemplat

e

DAOImpl

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Thank you

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