EclipseLink with Spring - Can't persist into D

问题:

I am using Spring + EclipseLink 2 to manage entity on a Derby database. Select object from db works fine but when I try to persist one, nothing happens. Program executes correctly and no exception are thrown. I probably did something wrong, as I'm not familiar with Spring, thanks for your comments and suggestions :)

The ServerDaoDb method :

@Transactional
public void addServer(Server server) {
    EntityManager em = emf.createEntityManager();
    emf.createEntityManager().persist(server);
    em.close();
}

Application context is :

 ... 
 <tx:annotation-driven />

    <bean id="entityManagerFactory"
        class="org.springframework.orm.jpa.LocalEntityManagerFactoryBean">
        <property name="persistenceUnitName" value="SpringPratiquePU" />
    </bean>

    <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
    <property name="entityManagerFactory" ref="entityManagerFactory"/>
</bean>
<bean 
class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor" />
<bean class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor"/>

Persistence.xml :

  <persistence-unit name="SpringPratiquePU" transaction-type="RESOURCE_LOCAL">
    <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
    <class>net.athom.spring.examples.models.eas.Server</class>
    <class>net.athom.spring.examples.models.eas.Node</class>
    <properties>
      <property name="eclipselink.target-database" value="DERBY"/>
      <property name="javax.persistence.jdbc.url" value="jdbc:derby://localhost:1527/SpringPratique"/>
      <property name="javax.persistence.jdbc.password" value="clem"/>
      <property name="javax.persistence.jdbc.driver" value="org.apache.derby.jdbc.ClientDriver"/>
      <property name="javax.persistence.jdbc.user" value="clem"/>
    </properties>
  </persistence-unit>
</persistence>

The Debug Trace :

DEBUG JpaTransactionManager:365 - Creating new transaction with name [net.athom.spring.examples.service.impl.ServerManagerImpl.addServer]: PROPAGATION_REQUIRED,ISOLATION_DEFAULT; ''
[EL Info]: 2010-10-29 15:33:27.443--ServerSession(14894886)--EclipseLink, version: Eclipse Persistence Services - 2.0.2.v20100323-r6872
[EL Info]: 2010-10-29 15:33:28.606--ServerSession(14894886)--file:/C:/netbeanProject/SpringPratique/src/_SpringPratiquePU login successful
15:33:28,893       DEBUG JpaTransactionManager:323 - Opened new EntityManager [org.eclipse.persistence.internal.jpa.EntityManagerImpl@1779885] for JPA transaction
15:33:28,951       DEBUG DefaultListableBeanFactory:242 - Returning cached instance of singleton bean 'transactionManager'
15:33:28,952       DEBUG JpaTransactionManager:286 - Found thread-bound EntityManager [org.eclipse.persistence.internal.jpa.EntityManagerImpl@1779885] for JPA transaction
15:33:28,953       DEBUG JpaTransactionManager:470 - Participating in existing transaction
15:33:29,266       DEBUG JpaTransactionManager:752 - Initiating transaction commit
15:33:29,267       DEBUG JpaTransactionManager:462 - Committing JPA transaction on EntityManager [org.eclipse.persistence.internal.jpa.EntityManagerImpl@1779885]
15:33:29,268       DEBUG JpaTransactionManager:548 - Closing JPA EntityManager [org.eclipse.persistence.internal.jpa.EntityManagerImpl@1779885] after transaction
15:33:29,308       DEBUG EntityManagerFactoryUtils:328 - Closing JPA EntityManager

回答1:

Your error is here:

@Transactional
public void addServer(Server server) {
    EntityManager em = emf.createEntityManager();
    emf.createEntityManager().persist(server);
    em.close();
}

Your are creating two different EntityManager instances, the em, which you are closing, and a new one at the next line with emf.createEntityManager() which you are using directly to persist your changes.

Try this:

@Transactional
public void addServer(Server server) {
    EntityManager em = emf.createEntityManager();
    em.persist(server);
    em.close();
}

I guess that when you close your em instance, your changes are written to the DB, but, in case that they are not, you have to add em.flush(); right before closing the em instance.

回答2:

I am not sure what exactly is wrong with your configuration (I guess EntityManager created manually can't participate in @Transactional transactions), but the typical JPA configuration in Spring looks like this, so you don't need to create EntityManager manually (also note the classname of the factory bean):

@PersistenceContext
private EntityManager em;

@Transactional  
public void addServer(Server server) {  
    em.persist(server);  
} 

---

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

回答3:

Thx for your answers, both were very helpful. I ended up using LocalContainerEntityManagerFactoryBean, so I could inject the entity manager into my dao. I added servlet-agent-2.5.6.jar on the lib folder and and pass VM options : -javaagent:path/to/lib/ervlet-agent-2.5.6.jar

Then I modified ApplicationContext.xml :

 <bean id="entityManagerFactory"
        class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="persistenceUnitName" value="SpringPratiquePU" />
         <property name="loadTimeWeaver">
<bean class="org.springframework.instrument.classloading.InstrumentationLoadTimeWeaver" />
    </property>
    </bean>

And my dao: ...

  @PersistenceContext
  private EntityManager em;


   @Transactional
   public void addServer(Server server) {
       em.persist(server);
   }

Persistence and transactions work like a charm now !