@PostConstruct中没有可用的事务性实体管理器 [英] No transactional entitymanager available in @PostConstruct

问题描述

entityManager.unwrap（SessionImplementor.class）原因没有事务性的entitymanager可用

代码：

  @Component 
 public class HibernateEventWiring {
 $ b $ @Autowired 
 private ViewListener listener; 
 
 @PersistenceContext（unitName =config-punit）
 private EntityManager entityManager; 
 
 @PostConstruct 
 public void registerListeners（）{
 SessionFactory sessionFactory = getSessionFactory（）; 
 EventListenerRegistry registry =（（SessionFactoryImpl）sessionFactory）.getServiceRegistry（）。getService（
 EventListenerRegistry.class）; 
 registry.getEventListenerGroup（EventType.PRE_UPDATE）.appendListener（listener）; 
 
 $ b @Transactional 
 private SessionFactory getSessionFactory（）{
 // EXCEPTION：无事务型实体管理器可用
返回entityManager.unwrap（SessionImplementor.class） .getFactory（）; 
 
 
 
 $ div $解析方案

这个极好的答案：



在@PostConstruct中（与InitializingBean接口中的afterPropertiesSet一样），没有办法确保所有的后处理已经完成，所以（的确）不会有事务。

< blockquote>

正如我所看到的，您不需要事务，也不需要实体管理器bean，而是实体管理器工厂bean。我认为你应该简单地自动调用EntityManagerFactory，然后从中解开Hibernate SessionFactory。

  @Autowired $ b $ private EntityManagerFactory entityManagerFactory ; 
 
 @PostConstruct 
 public void registerListeners（）{
 SessionFactory sessionFactory = entityManagerFactory.unwrap（SessionFactory.class）; 
 ... 
} 
  

Problem: entityManager.unwrap(SessionImplementor.class) cause no transactional entitymanager available exception.

Code:

@Component
public class HibernateEventWiring {

    @Autowired
    private ViewListener listener;

    @PersistenceContext(unitName = "config-punit")
    private EntityManager entityManager;

    @PostConstruct
    public void registerListeners() {
        SessionFactory sessionFactory = getSessionFactory();
        EventListenerRegistry registry = ((SessionFactoryImpl) sessionFactory).getServiceRegistry().getService(
                EventListenerRegistry.class);
        registry.getEventListenerGroup(EventType.PRE_UPDATE).appendListener(listener);
    }

    @Transactional
    private SessionFactory getSessionFactory() {
        // EXCEPTION: No transactional entitymanager available
        return entityManager.unwrap(SessionImplementor.class).getFactory(); 
    }
}

解决方案

According to this excelent answer:

In the @PostConstruct (as with the afterPropertiesSet from the InitializingBean interface) there is no way to ensure that all the post processing is already done, so (indeed) there can be no Transactions.

As I see, you do not need a transaction nor an entity manager bean, but rather an entity manager factory bean. I think you should simply autowire the EntityManagerFactory and then unwrap the Hibernate SessionFactory from it.

@Autowired
private EntityManagerFactory entityManagerFactory;

@PostConstruct
public void registerListeners() {
    SessionFactory sessionFactory = entityManagerFactory.unwrap(SessionFactory.class);
    ...
}

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