Java 使用 EntityManager 从 EJB 访问 Hibernate Session
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Accessing Hibernate Session from EJB using EntityManager
提问by Bogdan
Is it possible to obtain the Hibernate Session object from the EntityManager? I want to access some hibernate specific API...
是否可以从 EntityManager 获取 Hibernate Session 对象？我想访问一些休眠特定的 API...
I already tried something like:
我已经尝试过类似的东西：
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
但是一旦我在 EJB 中调用一个方法，我就会收到带有 NullPointerException 的“在 EJB 上调用期间发生系统异常”
I use glassfish 3.0.1
我使用玻璃鱼 3.0.1
采纳答案by Sean Patrick Floyd
Bozhoand partenonare correct, but:
In JPA 2, the preferred mechanism is entityManager.unwrap(class)
在 JPA 2 中，首选机制是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).
我认为你的异常是因为你试图转换为一个实现类（也许你正在处理一个 JDK 代理）。转换到一个接口，一切都应该没问题（在 JPA 2 版本中，不需要转换）。
回答by jpkrohling
As simple as:
就这么简单：
Session session = (Session) em.getDelegate();
回答by Bozho
If your EntityManageris properly injected (using @PersistenceContext) and is not null, then the following should work:
如果您EntityManager正确注入（使用@PersistenceContext）并且不为空，则以下内容应该有效：
org.hibernate.Session hSession = (Session) em.getDelegate();
回答by Mouscellaneous
From Hibernate EntityManager docs, the preferred way of doing it is:
从 Hibernate EntityManager 文档中，首选的做法是：
Session session = entityManager.unwrap(Session.class);
