java确实支持PersistenceContextType。延长？

Question

@Stateful EJB可以使用PersistenceContextType。扩展用于跨多个事务重用同一EntityManager。这在实现对话范围时很有用。Spring对此有任何支持吗

Answer 1

Spring有一个带有静态工厂方法的特殊类，用于创建扩展实体管理器。见ExtendedEntityManagerCreator

此外，如果您注入一个EntityManagerFactory并调用createEntityManager(SynchronizationType.SYNCHRONIZED)，它将创建具有扩展持久性上下文的实体管理器（在提交事务后，它不会自动分离实体）

Answer 2

在Implementing DAOs based on plain JPA中有一个简短的讨论：

The @PersistenceContext annotation has an optional attribute type, which defaults to PersistenceContextType.TRANSACTION. This default is what you need to receive a shared EntityManager proxy. The alternative, PersistenceContextType.EXTENDED, is a completely different affair: This results in a so-called extended EntityManager, which is not thread-safe and hence must not be used in a concurrently accessed component such as a Spring-managed singleton bean. Extended EntityManagers are only supposed to be used in stateful components that, for example, reside in a session, with the lifecycle of the EntityManager not tied to a current transaction but rather being completely up to the application.

所以不，听起来不像是弹簧支撑着它们

Answer 3

是的，春天支持它。例如，参见Injection of PersistenceContext with PersistenceContextType EXTENDED