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我正在尝试向一些现有演员发布消息，例如下面的节目，但可能有机会引用非现有演员，我想在发布消息之前知道。提前致谢

actor = getContext().actorFor("actorSystem/user/" + nameOfActor);
actor.tell("message",getSelf());
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4 回答 4

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您可以在发送实际消息之前向他们发送识别消息。所有参与者都理解它并且应该用 回复Self()。或者使用resolveOne方法：

您可以使用 ActorSelection 的 resolveOne 方法为 ActorSelection 获取 ActorRef。如果存在这样的 Actor，它会返回匹配的 ActorRef 的 Future。如果不存在这样的参与者或识别未在提供的超时内完成，则以失败 [[akka.actor.ActorNotFound]] 完成。

于 2013-09-16T06:44:51.747 回答
1

知道一个演员是否活着（没有 DeathWatch）的唯一可能方法是接收来自它的消息。这只能证明演员在某个时间点还活着（当它发送消息时）。

于 2013-09-18T11:39:00.380 回答
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实际上我需要处理收到的每条消息，如果一个演员不存在，那么该消息必须单独处理，我使用 Deadletter 实现来实现 

final ActorRef actor = actorSystem.actorOf(new Props(DeadLetterHandlerActor.class));
actorSystem.eventStream().subscribe(actor, DeadLetter.class);
于 2013-10-10T09:35:30.943 回答
0

以下是我如何实现使用 DeadLettersHandler 演员来处理 DeadLetters 的代码片段 

public class MyActor extends UntypedActor
{
 @Override
  public void onReceive(Object message) throws Exception 
  {
     System.out.println("MyActor received : "+message.toString());
  }
}

public class DeadLettersHandler extends UntypedActor
{
  public void onReceive(Object deadLetter) throws Exception
  {
   System.out.println("DeadLettersHandler received : "+deadLetter.toString());
  }
}


public class DeadLetterTest 
{
   public static void main(String[] args)
   {
     ActorSystem MyActorSystem = ActorSystem.create("MyActorSystem");
     ActorRef existingActor = MyActorSystem.actorOf(Props.create(MyActor.class),"ExistingActor");
     ActorRef DLH = MyActorSystem.actorOf(Props.create(DeadLettersHandler.class), "DeadLetterHandler");
     MyActorSystem.eventStream().subscribe(DLH, DeadLetter.class);
     ActorSelection nonExist = MyActorSystem.actorSelection("akka://user/MyActorSystem/NonExistingActor");
     existingActor.tell("Hello Akka", existingActor);
     nonExist.tell("Hello Akka", DLH);
     MyActorSystem.shutdown();
    }
}

 output:

 MyActor received : Hello Akka
 DeadLettersHandler received : DeadLetter(Hello Akka,Actor[akka://MyActorSystem/user/DeadLetterHandler#-3707992],Actor[akka://MyActorSystem/deadLetters])
 [INFO] [10/10/2013 15:43:43.343] [MyActorSystem-akka.actor.default-dispatcher-6] [akka://MyActorSystem/deadLetters] Message [java.lang.String] from Actor[akka://MyActorSystem/user/DeadLetterHandler#-3707992] to Actor[akka://MyActorSystem/deadLetters] was not delivered. [1] dead letters encountered. This logging can be turned off or adjusted with configuration settings 'akka.log-dead-letters' and 'akka.log-dead-letters-during-shutdown'.
于 2013-10-10T10:30:48.473 回答