persistence.xml in a Spring application

Question

I'm used to have persistence.xml in my projects in which I define the provider to use (hibernate in most cases).

However, I'm starting a new project in which it is mandatory to use Spring framework. I've seen some blogs describing the integration of Hibernate in Spring and I've understood that I should declare a session factory in spring's beans descriptor org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean

All the examples I've seen don't mention the use of persistence.xml, persistence context, entity manager...

I'm not sure I understand this point, I always thought that Hibernate is just a provider of JPA unless the factory declared in application-context.xml is doing something in background. If it is the case, I would like to understand how it is working..

thanks in advance...

Answer 1

AnnotationSessionFactoryBean is Factory bean implemented by Spring to create Hibernate Session Factory and shared to Spring's Application Context.if you are planning to use Direct Hibernate ( in case you dont need persistent.xml / per-cont.xml / entityManager) you can provide the properties in AnnotationSession FactoryBean. and can be injected in Any DAO.
How ever if you are planing to wire through JPA. Then you need ( persistent and persistent-context and entity Manager). In order to do that you required three steps
1. declare / configure Spring's JPA Adapter to create EntityManager instance for you

<bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">

Inside JPA Bean declaration provide details about your database and who is ORM provider such as ( hibernate /toplink / ....) in your case Hibernate

<property name="jpaVendorAdapter">
        <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
            <property name="showSql" value="true" />
            <property name="generateDdl" value="false" />
            <property name="databasePlatform"  value="org.hibernate.dialect.Oracle9Dialect"/>
        </bean>
    </property>

then Provide information about your persistent entity details in persistent.xml or some way

    <property name="persistenceXmlLocation" value="classpath:persistence.xml" />

if you have any specific JPA properties then

 <property name="jpaProperties">
      <props>
    <!--      <prop key="hibernate.cache.provider_class">
                org.hibernate.cache.EhCacheProvider
        </prop>
         -->
        <prop key="hibernate.format_sql">false</prop>
        <prop key="hibernate.use_sql_comments">false</prop>
      </props>
    </property>

Bottom line, Spring provies adapters to directly to Hibernate ( in that case your dont need Jpa files such as persistent.xml and so but you need hibernate related files like hbm files) or adapters to the JPA ( in that case you have provide details about who is JPA vendor and instrut spring how to connect to the JPA vendor).

Hope the above clarifies.