Well, as I myself fell into this stupid gap, I guess I'll try to help. I was quite pushed in this trap by a fallacious part of the jboss documentation :
@PersistenceContext EntityManager entityManager;
public void someMethod();
{
org.jboss.ejb3.entity.HibernateSession hs = (HibernateSession)entityManager;
org.hibernate.Session session = hs.getHibernateSession();
}Let's be clear : this is totally WRONG! Yes, it will work under JBoss, but as there's a standard way to do this, this is not the right way to do this.
In fact, there's a dedicated method that lets you retrieve the underlying persistence manager : EntityManager.getDelegate(). If you read this method's javadoc, you'll see the following :
/**
* Return the underlying provider object for the EntityManager,
* if available. The result of this method is implementation
* specific.
* @throws IllegalStateException if this EntityManager has been closed.
*/
public Object getDelegate();And the "underlying provider", for Hibernate, is obviously the Hibernate Session instance...
So, the right way to retrieve the Session is something like the following instead :
@PersistenceContext EntityManager entityManager;
public void someMethod();
{
org.hibernate.Session session = (Session)entityManager.getDelegate();
}Under JBoss, using this code won't make a big difference. But using the standard way will let you run your code under several appservers (namely, it works like a charm[1] under JBoss 4.2.2.ga and Glassfishv2ur1 for example). If you use the bad way above, this will just crash under Glassfish, for example...
I reported the corresponding documentation bug in the JBOSS tracker.
Hope this helps...
Notes
[1] ça, c'est pour Seb
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