Akka并发编程——第五节：Actor模型（四） 停止Actor

本节主要内容：
1. 停止Actor

1. 停止Actor

（1）通过ActorSystem.shutdown方法停止所有 Actor的运行

/**停止Actor:ActorSystem.shutdown方法*/object Example_10 extends App{  import akka.actor.Actor  import akka.actor.ActorSystem  import akka.actor.Props  class FirstActor extends Actor with ActorLogging{    var child:ActorRef = context.actorOf(Props[MyActor], name = "myActor")    def receive = {      //向MyActor发送消息      case x => child ! x;log.info("received "+x)    }    override def postStop(): Unit = {      log.info("postStop In FirstActor")    }  }  class MyActor extends Actor with ActorLogging{    def receive = {      case "test" => log.info("received test");      case _      => log.info("received unknown message");    }    override def postStop(): Unit = {      log.info("postStop In MyActor")    }  }  val system = ActorSystem("MyActorSystem")  val systemLog=system.log  //创建FirstActor对象  val firstactor = system.actorOf(Props[FirstActor], name = "firstActor")  systemLog.info("准备向firstactor发送消息")  //向firstactor发送消息  firstactor!"test"  firstactor! 123  //关闭ActorSystem，停止所有Acotr运行  system.shutdown()}

代码运行结果：

[INFO] [04/02/2016 21:51:34.440] [main] [ActorSystem(MyActorSystem)] 准备向firstactor发送消息[INFO] [04/02/2016 21:51:34.441] [MyActorSystem-akka.actor.default-dispatcher-4] [akka://MyActorSystem/user/firstActor/myActor] received test[INFO] [04/02/2016 21:51:34.441] [MyActorSystem-akka.actor.default-dispatcher-2] [akka://MyActorSystem/user/firstActor] received test[INFO] [04/02/2016 21:51:34.441] [MyActorSystem-akka.actor.default-dispatcher-2] [akka://MyActorSystem/user/firstActor] received 123[INFO] [04/02/2016 21:51:34.441] [MyActorSystem-akka.actor.default-dispatcher-4] [akka://MyActorSystem/user/firstActor/myActor] received unknown message[INFO] [04/02/2016 21:51:34.446] [MyActorSystem-akka.actor.default-dispatcher-4] [akka://MyActorSystem/user/firstActor/myActor] postStop In MyActor[INFO] [04/02/2016 21:51:34.447] [MyActorSystem-akka.actor.default-dispatcher-5] [akka://MyActorSystem/user/firstActor] postStop In FirstActor

（2）通过context.stop方法停止Actor的运行

/**停止Actor:context.stop方法*/object Example_11 extends App{  import akka.actor.Actor  import akka.actor.ActorSystem  import akka.actor.Props  class FirstActor extends Actor with ActorLogging{    var child:ActorRef = context.actorOf(Props[MyActor], name = "myActor")    def receive = {      case "stop"=>context.stop(child)      case x =>{        //向MyActor发送消息        child ! x        log.info("received "+x)      }    }    override def postStop(): Unit = {      log.info("postStop In FirstActor")    }  }  class MyActor extends Actor with ActorLogging{    def receive = {      case "test" => log.info("received test");      case _      => log.info("received unknown message");    }    override def postStop(): Unit = {      log.info("postStop In MyActor")    }  }  val system = ActorSystem("MyActorSystem")  val systemLog=system.log  //创建FirstActor对象  val firstactor = system.actorOf(Props[FirstActor], name = "firstActor")  systemLog.info("准备向firstactor发送消息")  //向firstactor发送消息  firstactor!"test"  firstactor! 123  firstactor!"stop"}

代码运行结果：

[INFO] [04/02/2016 22:02:48.760] [main] [ActorSystem(MyActorSystem)] 准备向firstactor发送消息[INFO] [04/02/2016 22:02:48.761] [MyActorSystem-akka.actor.default-dispatcher-5] [akka://MyActorSystem/user/firstActor/myActor] received test[INFO] [04/02/2016 22:02:48.761] [MyActorSystem-akka.actor.default-dispatcher-2] [akka://MyActorSystem/user/firstActor] received test[INFO] [04/02/2016 22:02:48.762] [MyActorSystem-akka.actor.default-dispatcher-2] [akka://MyActorSystem/user/firstActor] received 123[INFO] [04/02/2016 22:02:48.762] [MyActorSystem-akka.actor.default-dispatcher-5] [akka://MyActorSystem/user/firstActor/myActor] received unknown message[INFO] [04/02/2016 22:02:48.763] [MyActorSystem-akka.actor.default-dispatcher-5] [akka://MyActorSystem/user/firstActor/myActor] postStop In MyActor

代码的重点为

class FirstActor extends Actor with ActorLogging{    var child:ActorRef = context.actorOf(Props[MyActor], name = "myActor")    def receive = {      case "stop"=>context.stop(child)      case x =>{        //向MyActor发送消息        child ! x        log.info("received "+x)      }    }    override def postStop(): Unit = {      log.info("postStop In FirstActor")    }  }

中的case “stop”=>context.stop(child)，直接通过context.stop方法停止Actor的运行。注意程序中并没有使用system.shutdown方法，因此整个程序的不会停止，如下图所示

（3）通过akka.actor.PoisonPill消息停止Actor的运行

/**停止Actor:使用akka.actor.PoisonPill*/object Example_12 extends App{  import akka.actor.Actor  import akka.actor.ActorSystem  import akka.actor.Props  import akka.actor.PoisonPill  class FirstActor extends Actor with ActorLogging{    var child:ActorRef = context.actorOf(Props[MyActor], name = "myActor")    def receive = {      //向child发送PoisonPill停止其运行      case "stop"=>child!PoisonPill      case x =>{        //向MyActor发送消息        child ! x        log.info("received "+x)      }    }    override def postStop(): Unit = {      log.info("postStop In FirstActor")    }  }  class MyActor extends Actor with ActorLogging{    def receive = {      case "test" => log.info("received test");      case _      => log.info("received unknown message");    }    override def postStop(): Unit = {      log.info("postStop In MyActor")    }  }  val system = ActorSystem("MyActorSystem")  val systemLog=system.log  //创建FirstActor对象  val firstactor = system.actorOf(Props[FirstActor], name = "firstActor")  systemLog.info("准备向firstactor发送消息")  //向firstactor发送消息  firstactor!"test"  firstactor! 123  firstactor!"stop"}

代码运行结果：

[INFO] [04/02/2016 22:12:09.947] [main] [ActorSystem(MyActorSystem)] 准备向firstactor发送消息[INFO] [04/02/2016 22:12:09.947] [MyActorSystem-akka.actor.default-dispatcher-2] [akka://MyActorSystem/user/firstActor/myActor] received test[INFO] [04/02/2016 22:12:09.947] [MyActorSystem-akka.actor.default-dispatcher-4] [akka://MyActorSystem/user/firstActor] received test[INFO] [04/02/2016 22:12:09.947] [MyActorSystem-akka.actor.default-dispatcher-4] [akka://MyActorSystem/user/firstActor] received 123[INFO] [04/02/2016 22:12:09.947] [MyActorSystem-akka.actor.default-dispatcher-2] [akka://MyActorSystem/user/firstActor/myActor] received unknown message[INFO] [04/02/2016 22:12:09.951] [MyActorSystem-akka.actor.default-dispatcher-4] [akka://MyActorSystem/user/firstActor/myActor] postStop In MyActor

代码与Exampel_11中的不同之处在于

//向child发送PoisonPill停止其运行case "stop"=>child!PoisonPill

它使用不是context.stop方法，而是向MyActor发送了PoisonPill消息，其它代码不变。

还有一种gracefulStop方法可以停止Actor的运行，这部分内容等了解完Future类的作用原理之后再来讨论