从JPA的EMF中得到Hibernate的SessionFactory，参考：http://www.jroller.com/RickHigh/entry/getting_sessionfactory_from_entitymanagerfactory_in

GetSessionFactoryFromEMF.java

public static SessionFactory getSessionFactory(EntityManagerFactory hemf) {
  return ((HibernateEntityManagerFactory)hemf).getSessionFactory();
}

GetSessionFromEM.java

//得到hibernate的session
//http://stackoverflow.com/questions/4335570/accessing-hibernate-session-from-ejb-using-entitymanager

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