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Spring Data Access. By, Srinivas Reddy.S. www.JAVA9S.com. Introduction to Spring JDBC. www.JAVA9S.com. Multiple ways to connect to DB. JDBC IBATIS Hibernate JPA JCA. www.JAVA9S.com. Layered architecture. Security. Controller. Service. DAO. DB. client. www.JAVA9S.com.
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Spring Data Access By, Srinivas Reddy.S www.JAVA9S.com
Introduction to Spring JDBC www.JAVA9S.com
Multiple ways to connect to DB • JDBC • IBATIS • Hibernate • JPA • JCA www.JAVA9S.com
Layered architecture Security Controller Service DAO DB client www.JAVA9S.com
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. www.JAVA9S.com
DAO Layer Service Layer DAO Interfaces DAOImplementations DB www.JAVA9S.com
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. www.JAVA9S.com
Problems with JDBC • Poor Exception hierarchy • SQLException • DataTruncation • SQLWarning • BatchUpdateException • Issues with JDBC Exceptions: • Least explantive • Defined as checked exceptions which mandate us to write the catch blocks www.JAVA9S.com
Spring Exception hirerarchy CannotAcquireLockException CannotSerializeTransactionException CleanupFailureDataAccessException ConcurrencyFailureException DataAccessException DataAccessResourceFailureException DataIntegrityViolationException DataRetrievalFailureException DeadlockLoserDataAccessException www.JAVA9S.com
Spring Exception hirerarchy EmptyResultDataAccessException IncorrectResultSizeDataAccessException IncorrectUpdateSemanticsDataAccessException InvalidDataAccessApiUsageException InvalidDataAccessResourceUsageException OptimisticLockingFailureException PermissionDeniedDataAccessException PessimisticLockingFailureException TypeMismatchDataAccessException UncategorizedDataAccessException www.JAVA9S.com
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. www.JAVA9S.com
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 www.JAVA9S.com
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. www.JAVA9S.com
Data access templates in Spring • JdbcTemplate • NamedParameterJdbcTemplate • SimpleJdbcTemplate • HibernateTemplate • JpaTemplate • SqlMapClientTemplate • JdoTemplate • CciTemplate www.JAVA9S.com
JDBCTemplate Dependencies JDBC Template Data source DAO Impl www.JAVA9S.com
Spring JDBC Configuration steps • Choose a data source type: • Data sources by JDBC API. • DriverManagerDataSource • SingleConnectionDataSource • Data sources looked up by JNDI. • <jee:jndi-lookup id="dataSource" jndi-name="/jdbc/springjdbc" resource-ref="true" /> • Data sources that pool connections. • Using Apache commons DBCP • org.apache.commons.dbcp.BasicDataSource www.JAVA9S.com
Spring JDBC Configuration steps • 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> www.JAVA9S.com
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> www.JAVA9S.com
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> www.JAVA9S.com
JDBCTemplate Dependencies JDBC Template Data source DAO Impl www.JAVA9S.com
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