akka ask

import akka.actor.{Actor, ActorSystem, Props}
import akka.util.Timeout
import akka.pattern.ask

import scala.concurrent.duration.Duration
import scala.util.Failure

class testAskActor extends Actor{
   override def receive = {
    case msg: String =>
      sender ! msg.toUpperCase
  }
}

object testAsk {
  def main(args:Array[String]) = {
    val system = ActorSystem.create("testAsk")
    val testActor = system.actorOf(Props[testAskActor])

    import system.dispatcher

    implicit val timeout = new Timeout(Duration.create(1, "seconds"))
    val fut = testActor ? "hello"
    fut.onComplete{
      case failed:Failure[akka.pattern.AskTimeoutException] => println(s"failed=" + failed)
      case result => println(s"$result")
    }
  }
}

超时时输出如下的log：
 failed=Failure(akka.pattern.AskTimeoutException: Ask timed out on [Actor[akka://testAsk/user/$a#887126484]] after [1000 ms]. Sender[null] sent message of type "java.lang.String".)