EJB3 如何确保在删除 bean 之前发生事情
假设我让我的客户使用 Stateful Session Bean 预订飞机上的座位。如果客户端显式调用我的Remove方法，那么他的所有保留都将被取消，并且该bean随后将被删除。
但是，如果客户端空闲一段时间并且 Bean 被钝化，如果 Bean 在钝化时超时，它将被删除，而不会调用我的任何函数。因此，如果有人能告诉我如何确保在 bean 被删除时预订会被取消，我将非常感激。如果我使用@PreDestroy注解，可以解决这个问题吗？
此致， 詹姆斯·特兰
Suppose I let my customer reserve seats on a plane using Stateful Session Bean. If the client explicitly calls my Remove method, all of his reservations will be cancelled and the bean is removed afterward.
However, in case the client is idle for some time and the Bean get passivated, if the Bean times out while being passivated, it would be deleted without calling any of my functions. Hence, I'd be very grateful if someone could show me how I can make sure that the reservations would be cancelled if the bean get deleted. If I use the @PreDestroy annotation, will it solve this problem?
Best regards,
James Tran
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评论（3）
@PreDestroy方法很可能不会被调用。 EJB 3.1 规范明确指出：该规范还详细说明了如果在这种情况下不调用 @PreDestroy 方法，如何删除资源：
就您而言，这取决于您存储预订状态的方式。如果它们保留在数据库中，那么我建议采用与规范中规定的相同的方法。您可以使用 EJB 计时器服务定期执行此活动，或者使用 Quartz 等调度程序。请注意，必须区分不再存在的钝化会话 bean 实例的内容和将再次准备好的会话 bean 实例的内容。
It is quite possible for the
@PreDestroymethod to not be invoked. The EJB 3.1 specification, explicitly states this:The specification also details how resources may be removed if the
@PreDestroymethod is not invoked in such scenarios:In your case, it would depend on how you are storing the state of your reservations. If they are persisted in the database, then I would suggest employing the same approach as mandated in the specification. You could use the EJB Timer service, to perform this activity periodically, or use a scheduler like Quartz. Note, that it is imperative to distinguish between the contents of passivated session bean instances that no longer exist, and those that will be made ready once again.
钝化的 bean 将在超时时被销毁，因此任何用
@PreDestroy注释的方法都将执行您正在寻找的操作。当 A 处于活动状态时，A 的 Stateful bean 实例不会与 B 共享，直到 A 的实例被销毁。请参阅本文中的图表供进一步阅读
A passivated bean will get destroyed on timeout and hence any method annotated with
@PreDestroywill do what you are looking for.While A is active, A's instance of the Stateful bean will not be shared with B until A's instance is destroyed. See the diagram on this article for further reading
是的，应该的。用
@PreDestroy注释的方法将在bean删除之前被调用（即使i在钝化状态下超时）Yes it should. The method annotated with
@PreDestroywill be called prior to bean removal (even if i times-out in the passivated state)