spring - 如何在没有事件 session 的情况下将实体监听器添加到 JPA (EclipseLink) 实体？

Question

我正在尝试在 spring bean 中执行以下操作:

@PostConstruct
public void registerTorchEntityListeners()
{
    Session session = entityManager.unwrap(Session.class);
    for (EntityType<?> entity : entityManager.getMetamodel().getEntities())
    {
        if (entity.getJavaType().isAnnotationPresent(TorchEntityListeners.class))
        {
             TorchEntityListeners annotation = (TorchEntityListeners) entity.getJavaType().getAnnotation(TorchEntityListeners.class);
             for (Class listenerClass : annotation.value())
             {
                 Map<String, DescriptorEventListener> map = applicationContext.getBeansOfType(listenerClass);
                 for (DescriptorEventListener listenerBean : map.values())
                 {
                     session.getClassDescriptor(entity.getClass()).getEventManager().addListener(listenerBean);
                 }
             }
        }
    }

}

问题是我得到以下异常，因为(我认为)我不在事务中，因此没有可用于获取 ClassDescriptor 的 session ，以便我可以向特定实体添加监听器:

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'torchEntityListenerConfigurer': Invocation of init method failed; nested exception is java.lang.IllegalStateException: No transactional EntityManager available
    at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor.postProcessBeforeInitialization(InitDestroyAnnotationBeanPostProcessor.java:133)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsBeforeInitialization(AbstractAutowireCapableBeanFactory.java:396)

基本上我正在尝试执行与此等效的 EclipseLink:http://invariantproperties.com/2013/09/29/spring-injected-beans-in-jpa-entitylisteners/ 。我更愿意用监听器注释实体，而不是执行如下操作:Injecting a Spring dependency into a JPA EntityListener .

想法？

Answer 1

当然，我在添加赏金后 30 分钟就弄清楚了:)

我最终通过从 EntityManagerFactory 中的连线获取实体管理器(而不是使用:@PersistenceContext 将其注入(inject)到 TorchEntityListenerConfigurer 中)来实现此目的

这是可行的解决方案......而且效果很好!

这是配置:

<bean id="approvalEntityListener" class="com.prometheus.torchlms.core.activity.approval.ApprovalEntityListener">
    <property name="activityRepository" ref="activityRepository" />
    <property name="notificationFactory" ref="notificationFactory" />
    <property name="notificationService" ref="notificationService" />
</bean>
<bean id="springEntityListenerConfigurer" class="com.prometheus.torchlms.core.SpringEntityListenerConfigurer">
    <constructor-arg ref="entityManagerFactory" />
</bean>

这就是神奇发生的地方(如果这对某人有用):

public class SpringEntityListenerConfigurer implements ApplicationContextAware
{
    private ApplicationContext applicationContext;
    private EntityManagerFactory entityManagerFactory;

    public SpringEntityListenerConfigurer(EntityManagerFactory entityManagerFactory)
    {
        this.entityManagerFactory = entityManagerFactory;
    }

    @Override
    public void setApplicationContext(ApplicationContext applicationContext)
            throws BeansException
    {
        this.applicationContext = applicationContext;
    }

    @PostConstruct
    public void registerTorchEntityListeners()
    {
        //entityManager.
        EntityManager entityManager = entityManagerFactory.createEntityManager();
        Session session = entityManager.unwrap(Session.class);
        for (EntityType<?> entity : entityManagerFactory.getMetamodel().getEntities())
        {
            if (entity.getJavaType().isAnnotationPresent(SpringEntityListeners.class))
            {
                 SpringEntityListeners annotation = (SpringEntityListeners) entity.getJavaType().getAnnotation(SpringEntityListeners.class);
                 for (Class listenerClass : annotation.value())
                 {
                     Map<String, DescriptorEventListener> map = applicationContext.getBeansOfType(listenerClass);
                     for (DescriptorEventListener listenerBean : map.values())
                     {
                         ClassDescriptor classDescriptor = session.getClassDescriptor(entity.getJavaType());
                         if (null != classDescriptor)
                         {
                             classDescriptor.getEventManager().addListener(listenerBean);
                         }
                     }
                 }
            }
        }

    }
}

现在我可以将我的 @SpringEntityListeners({ApprovalEntityListener.class}) 添加到我想要的任何实体以及我想要的任何监听器，并且这些监听器可以是 spring beans!

如果它有帮助，这里是注释:

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
public @interface SpringEntityListeners
{
    Class<?>[] value();
}