我有一个Java对象,它不是一个从Actudio选择(PATH)选择演员系统的演员。系统中可能不存在选定的参与者。
在Java API ASK()中不存在用于ACTROL选择,所以我不能发送和识别消息给演员选择并使用发送者的响应。
我试图通过演员选择将信息发送给演员,然后对死信作出反应来解决这个问题。但我没有收到死信。
如果演员还活着或不存在,我该如何检查演员选举?
ActorSystem system = ActorSystem.create("test");
//create test actor
system.actorOf(Props.create(TestActor.class), "testActor");
//add dead letter listener to the system
ActorRef eventBusActor = asys.actorOf(Props.create(EventBusActor.class), "eventbusactor");
system.eventStream().subscribe(eventBusActor, DeadLetter.class);
//This works. The test actor receives the message
ActorSelection a1 = asys.actorSelection("/user/testActor");
a1.tell("hello", ActorRef.noSender());
//This does not work and does not send dead letters
ActorSelection a2 = asys.actorSelection("/user/doesnotexist");
a2.tell("hello", ActorRef.noSender());
//Does not compile, because ask needs an ActorRef as first argument
ActorSelection a3 = asys.actorSelection("/user/test");
Future f = Patterns.ask(a3, new Identify(), 1000);
最佳答案:
它看起来像Akka在Java API上对ActorSelection
的ask
的支持。我玩了一点代码,发现了一些有用的东西。查看此代码是否适用于您:
import java.util.concurrent.TimeUnit;
import scala.concurrent.Await;
import scala.concurrent.Future;
import akka.actor.ActorIdentity;
import akka.actor.ActorRef;
import akka.actor.ActorSelection;
import akka.actor.ActorSystem;
import akka.actor.Identify;
import akka.actor.Props;
import akka.pattern.AskableActorSelection;
import akka.util.Timeout;
public class AskTest {
public static void main(String[] args) throws Exception{
ActorSystem sys = ActorSystem.apply("test");
sys.actorOf(Props.create(TestActor.class), "mytest");
ActorSelection sel = sys.actorSelection("/user/mytest");
Timeout t = new Timeout(5, TimeUnit.SECONDS);
AskableActorSelection asker = new AskableActorSelection(sel);
Future<Object> fut = asker.ask(new Identify(1), t);
ActorIdentity ident = (ActorIdentity)Await.result(fut, t.duration());
ActorRef ref = ident.getRef();
System.out.println(ref == null);
}
}
我只是看看Scala如何请求支持,并通过Java钩住了它。这对我有用,我希望它对你有用。