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Hibernate

There are many different ways to configure Hibernate with Spring - first of all you can use either JPA or Hibernate Session, and then you have various choices like using hibernate.cfg.xml or not using one, specifying database information in Spring or in Hibernate, creating a data source in Spring or getting one from JNDI, and so on. Here I'll describe the way that I think is the best and the simplest.

Make the following changes to the Spring MVC application we created in the previous step:

1. Add the following dependencies:

  • org.hibernate:hibernate-entitymanager
  • org.springframework:spring-orm
  • commons-dbcp:commons-dbcp
  • postgresql:postgresql

commons-dbcp is for database connection pooling, which is always useful. postgresql is the database driver.

2. Add a file src/main/resources/META-INF/persistence.xml as follows:

<persistence xmlns="http://java.sun.com/xml/ns/persistence"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/persistence
        http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
    version="2.0">

    <persistence-unit name="sham">
        <provider>org.hibernate.ejb.HibernatePersistence</provider>
        <properties>
            <property name="hibernate.dialect" value="org.hibernate.dialect.PostgreSQLDialect" />
            <property name="hibernate.connection.driver_class" value="org.postgresql.Driver" />
        </properties>
    </persistence-unit>

</persistence>

This file provides the information about the JPA Entity Manager provider.

3. Add the following to spring.xml:

    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
        <property name="url" value="jdbc:postgresql://localhost:5432/sham" />
        <property name="username" value="cysun" />
        <property name="password" value="abcd" />
        <property name="initialSize" value="1" />
        <property name="maxActive" value="20" />
    </bean>

    <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="persistenceUnitName" value="sham" />
        <property name="dataSource" ref="dataSource" />
    </bean>

    <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
        <property name="entityManagerFactory" ref="entityManagerFactory" />
    </bean>

    <bean class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor" />

    <context:annotation-config />

    <tx:annotation-driven />

    <context:component-scan base-package="sham.model" />

It adds four beans: a data source, an entity manager factory, a transaction manager, and an exception translator that translates various SQL/database exceptions into a Spring exception. <context:annotation-config> enables annotations like @Autowired and @PersistenceContext (which is like an @Autowired specifically for entity manager), <tx:annotation-driven> enables annotations like @Transactional, and <context:component-scan> looks for beans under the package sham.model and its sub-packages (presumably that's where your DAO classes are located).

Note that because <tx:annotation-driven> is in the tx namespace, you need to add that namespace to spring.xml so it would look like this:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd  
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-3.0.xsd
        http://www.springframework.org/schema/tx
        http://www.springframework.org/schema/tx/spring-tx-3.0.xsd">
... ...
</beans>

And that is it. Now the application is a web application with both Spring and Hibernate. Here is some code you can use for testing:
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