如何用actorSelection选择akka actor？

Question

我试图选择一个已经创建的actor.这是一个代码:

val myActor = system.actorOf(Props(classOf[MyActor]), "myActorName")
println("myActor path - " + akka.serialization.Serialization.serializedActorPath(myActor))
println("Selection from spec akka://unit-test/user/myActorName " + system.actorSelection("akka://unit-test/user/myActorName").resolveOne().value)
println("Selection from spec /user/myActorName/ " + system.actorSelection("/user/myActorName/").resolveOne().value)

结果是:

myActor path - akka.tcp://unit-test@127.0.0.1:46635/user/myActorName#1444872428
Selection from spec akka://unit-test/user/myActorName None
Selection from spec /user/myActorName/ None

我也可以向演员传递一个消息,它完成得很好.我在actorSelection期间错过了什么？如何正确选择演员？

更新

这很奇怪,但是当我system.actorSelection("/user/myActorName/").resolveOne().value 用system.actorFor("/user/myActorName/")一切工作取代时.我的意思是actorFor回报一个演员.(由于actorFor弃用,这不是一个正确的解决方案)

Answer 1

请小心期货.在您的情况下,您收到的未来可能未在呼叫时刻完成 - 因此其值可能为空:

scala> println("Selection from spec /user/myActorName/ " +   system.actorSelection("/user/myActorName/").resolveOne().value)
Selection from spec /user/myActorName/ None

VS

scala> val fut =   system.actorSelection("/user/myActorName/").resolveOne()
fut: scala.concurrent.Future[akka.actor.ActorRef] = scala.concurrent.impl.Promise$DefaultPromise@7eb8d7bd

<just wait some time here>

scala> fut.value
res21: Option[scala.util.Try[akka.actor.ActorRef]] = Some(Success(Actor[akka://default/user/myActorName#1625966960]))

要正确获取值,请使用onComplete或just for-comprehesion/map:

import scala.concurrent.ExecutionContext.Implicits.global

for (res <- system.actorSelection("/user/myActorName").resolveOne()) {
   println(res)
}

请记住,onComplete/for是作为侦听器实现的,因此它们可能在不同的线程中执行.如果你需要当前线程的结果 - 使用经典Await.result(它的阻塞 - 所以,你应该在actor的上下文之外做receive).