Akka并发编程——第八节：Actor模型（七）

本节主要内容

停止运行Typed Actor

当Typed Actor不再需要时要将其停止，有3种方法停止Typed Actor的运行：

（1）通过system.shutdown()停止ActorSystem中所有的Typed Actor；

（2）调用TypedActor(system).stop(mySquarer)停止指定的Typed Actor；

（3）调用TypedActor(system).poisonPill(otherSquarer)停止指定的Typed Actor。

具体使用代码如下：

/*
 * 停止Typed Actor
 */
object Example_3 extends  App {

  import akka.event.Logging
  import scala.concurrent.{ Promise, Future }
  import akka.actor.{ TypedActor, TypedProps }
  import scala.concurrent.duration._

  trait Squarer {
    //fire-and-forget消息
    def squareDontCare(i: Int): Unit
    //非阻塞send-request-reply消息
    def square(i: Int): Future[Int]
    //阻塞式的send-request-reply消息
    def squareNowPlease(i: Int): Option[Int]
    //阻塞式的send-request-reply消息
    def squareNow(i: Int): Int
  }

  //混入PostStop和PreStart
  class SquarerImpl(val name: String) extends  Squarer with PostStop with PreStart {
    import TypedActor.context
    val log = Logging(context.system,TypedActor.self.getClass())
    def this() = this("SquarerImpl")

    def squareDontCare(i: Int): Unit = i * i
    def square(i: Int): Future[Int] = Promise.successful(i * i).future
    def squareNowPlease(i: Int): Option[Int] = Some(i * i)
    def squareNow(i: Int): Int = i * i

    def postStop(): Unit={
      log.info ("TypedActor Stopped")
    }
    def preStart(): Unit={
      log.info ("TypedActor  Started")
    }
  }

  val system = ActorSystem("TypedActorSystem")
  val log = Logging(system, this.getClass)

  //使用默认构造函数创建Typed Actor
  val mySquarer: Squarer =
    TypedActor(system).typedActorOf(TypedProps[SquarerImpl](),"mySquarer")

  //使用非默认构造函数创建Typed Actor
  val otherSquarer: Squarer =
    TypedActor(system).typedActorOf(TypedProps(classOf[Squarer],
      new SquarerImpl("SquarerImpl")), "otherSquarer")

  //Request-reply-with-future 消息发送
  val fSquare = mySquarer.square(10)
  val result = Await.result(fSquare, 5 second)
  log.info("fSquare="+result)

  //调用poisonPill方法停止Actor运行
  TypedActor(system).poisonPill(otherSquarer)

  //调用stop方法停止Actor运行
  TypedActor(system).stop(mySquarer)

  //system.shutdown()
}

代码运行结果如下所示。

[INFO] [03/21/2016 22:41:51.119] [TypedActorSystem-akka.actor.default-dispatcher-2] [$Proxy0(akka://TypedActorSystem)] TypedActor  Started
[INFO] [03/21/2016 22:41:51.123] [TypedActorSystem-akka.actor.default-dispatcher-2] [$Proxy1(akka://TypedActorSystem)] TypedActor  Started
[INFO] [03/21/2016 22:41:51.124] [main] [Example12_10$(akka://TypedActorSystem)] fSquare=100
[INFO] [03/21/2016 22:41:51.131] [TypedActorSystem-akka.actor.default-dispatcher-5] [$Proxy1(akka://TypedActorSystem)] TypedActor Stopped
[INFO] [03/21/2016 22:41:51.131] [TypedActorSystem-akka.actor.default-dispatcher-3] [$Proxy0(akka://TypedActorSystem)] TypedActor Stopped

代码中类SquarerImpl 混入了PreStart和PostStop两个trait：class SquarerImpl(val name: String) extends Squarer with PostStop with PreStart，这样的话在创建TypedActor之前和停止TypedActor后能够进行相应的操作，本例中主要是为监视TypedActor的创建和停止过程。代码TypedActor(system).stop(mySquarer)通过stop方法停止TypedActor，而TypedActor(system)

.poisonPill(otherSquarer)通过调用poisonPill方法停止运行TypedActor。