Question

如何从JPA 2.0 EntityManager获得Hibernate Session

Answer 1

1、获得Hibernate Session
Session session = entityManager.unwrap(org.hibernate.Session.class);

2、获得java.sql.Connection
方法1：
JPA 2.0
entityManager.getTransaction().begin();
java.sql.Connection connection = entityManager.unwrap(java.sql.Connection.class);
...
entityManager.getTransaction().commit();

但是对于Hibernate3.6.5会报错PersistenceException包含如下信息：Hibernate cannot unwrap interface java.sql.Connection
方法2：
SessionImplementor session =entityManager.unwrap(SessionImplementor.class);
session.connection();

方法3：
Session session = (org.hibernate.Session) em.getDelegate();
SessionFactoryImplementor sf = (SessionFactoryImplementor) session.getSessionFactory();
connection = sf.getConnectionProvider().getConnection();

hibenate 4.3 :
Session session = (Session) em.getDelegate();
SessionFactoryImpl sessionFactory = (SessionFactoryImpl) session.getSessionFactory();
connection = sessionFactory.getConnectionProvider().getConnection();