Question

I'm trying to generate and handle an event when my MDB receives a message. Here is what I'm doing:

public class MDBBooks implements MessageListener {
@Inject 
private Event<Update> messageReceived;

public MDBLibri() {
}

@Override
public void onMessage(Message message) {
    System.out.println("Message received");
    try {
        Update u = message.getBody(Update.class);
        messageReceived.fire(u);
        if(u != null){
            ... stuff        
        }
    } catch (JMSException ex) {
        System.out.println("JMSException: " + ex.getMessage());
    }
}

public void eventHandler(@Observes Update up) {
    System.out.println("There was an update");
}

}

But it just does not work, the string "There was an update" it's not printed in the glassfish console. I can't really tell what's the problem, my textbook does it the same way pretty much. I'm assuming the event fires fine, but the event handler isn't notified.

Answer 1

您是正确的观察者方法未得到通知。事实上，CDI甚至不知道它存在。原因是在CDI中，消息驱动的bean是非上下文对象。为简化起见，它们不被视为CDI bean，但您仍然可以注入它们并拦截它们。

现在，要让CDI识别观察者方法，您必须将其放在托管bean或会话bean 中。引用规范：

observer方法是托管bean类或会话bean类（或扩展，如Container生命周期事件中定义的）的非抽象方法。

因此，您的解决方案是将您的observer方法放在另一个类中，该类是托管bean或会话bean。

Event not working in Message Driven Bean

1 个答案: