Accessing Hibernate Session from EJB using EntityManager

Question

Is it possible to obtain the Hibernate Session object from the EntityManager? I want to access some hibernate specific API...

I already tried something like:

org.hibernate.Session hSession =
   ( (EntityManagerImpl) em.getDelegate() ).getSession();

but as soon as I invoke a method in the EJB I get "A system exception occurred during an invocation on EJB" with a NullPointerException

I use glassfish 3.0.1

Answer 1

Bozho and partenon are correct, but:

In JPA 2, the preferred mechanism is entityManager.unwrap(class)

HibernateEntityManager hem = em.unwrap(HibernateEntityManager.class);
Session session = hem.getSession();

I think your exception is caused because you are trying to cast to an implementation class (perhaps you were dealing with a JDK proxy). Cast to an interface, and everything should be fine (in the JPA 2 version, no casting is needed).

Answer 2

从Hibernate EntityManager文档中，首选的方法是：

Session session = entityManager.unwrap(Session.class);

Answer 3

很简单：

Session session = (Session) em.getDelegate();

Answer 4

如果您的EntityManager已正确注入（使用@PersistenceContext ）并且不为null，则以下内容应该有效：

org.hibernate.Session hSession = (Session) em.getDelegate();