Spring & Hibernate Integration

● SessionFactory object is Dependency-Injected

● HibernateTemplate class is provided

Setting up Hibernate SesssionFactory

DataSource Setup Through DI

<beans> <bean id="myDataSource" class="org.apache.commons.dbcp.BasicDataSource" destroymethod="close"> <property name="driverClassName" value="org.hsqldb.jdbcDriver"/> <property name="url" value="jdbc:hsqldb:hsql://localhost:9001"/> <property name="username" value="sa"/> <property name="password" value=""/> </bean> <bean id="mySessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean"> <property name="dataSource" ref="myDataSource"/> <property name="mappingResources"> <list> <value>product.hbm.xml</value> </list> </property> <property name="hibernateProperties"> <value> hibernate.dialect=org.hibernate.dialect.HSQLDialect </value> </property> </bean> </beans>

HibernateTemplate

● Helper class that simplifies Hibernate data access code

● Automatically converts HibernateExceptions into DataAccessExceptions, following the org.springframework.dao exception hierarchy

● The central method is execute, supporting Hibernate access code implementing the HibernateCallback interface.

● It provides Hibernate Session handling such that neither the HibernateCallback  implementation nor the calling code needs to explicitly care about retrieving/closing Hibernate Sessions, or handling Session lifecycle exceptions.

● For typical single step actions, there are various convenience methods (find, load, saveOrUpdate, delete).

HibernateTemplate Example

SessionFactory sessionFactory= HibernateFactory.getSessionFactory(); HibernateTemplate template= new HibernateTemplate(sessionFactory); Event event1 = new Event("Event 1"); Event event2 = new Event("Event 2"); Event event3 = new Event("Event 3"); template.save(event1); template.save(event2); template.save(event3); template.execute(new HibernateCallback() { public Object doInHibernate(Session session) throws HibernateException, SQLException { Query query = session.createQuery("from Event"); query.setMaxResults(2); List events = query.list(); for (Iterator it = events.iterator(); it.hasNext();) { Event event = (Event) it.next(); System.out.println(event.getName()); event.setDuration(60); } return null; } });

What Supporting Services Do We Need?

● Must solve the problem of data access exceptions to have independent DAO interfaces

– Can't throw SQLException or JDOException

– Catch/warp leads to huge redundancy

● Ex) Catch SQLException throw MyFunnyDaoException

– Need meaningful exceptions

● Not just one SQLException

● Need to be able to catch at different levels

– Data access exceptions should be unchecked