java - @PostConstruct 中没有可用的事务实体管理器

Question

问题:entityManager.unwrap(SessionImplementor.class) 导致没有可用的事务实体管理器异常。

代码:

@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(); 
    }
}

Answer 1

根据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.

正如我所见，您不需要事务，也不需要实体管理器 bean，而是需要实体管理器工厂 bean。我认为您应该简单地 Autowiring EntityManagerFactory，然后从中解开 Hibernate SessionFactory。

@Autowired
private EntityManagerFactory entityManagerFactory;

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