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

  1. /*
  2. *停止Actor:ActorSystem.shutdown方法
  3. */
  4. object Example_10 extends App{
  5.   import akka.actor.Actor
  6.   import akka.actor.ActorSystem
  7.   import akka.actor.Props
  8.   class FirstActor extends Actor with ActorLogging{
  9.     var child:ActorRef = context.actorOf(Props[MyActor], name = "myActor")
  10.     def receive = {
  11.       //向MyActor发送消息
  12.       case x => child ! x;log.info("received "+x)
  13.     }
  14.     override def postStop(): Unit = {
  15.       log.info("postStop In FirstActor")
  16.     }
  17.   }
  18.   class MyActor extends Actor with ActorLogging{
  19.     def receive = {
  20.       case "test" => log.info("received test");
  21.       case _      => log.info("received unknown message");
  22.     }
  23.     override def postStop(): Unit = {
  24.       log.info("postStop In MyActor")
  25.     }
  26.   }
  27.   val system = ActorSystem("MyActorSystem")
  28.   val systemLog=system.log
  29.   //创建FirstActor对象
  30.   val firstactor = system.actorOf(Props[FirstActor], name = "firstActor")
  31.   systemLog.info("准备向firstactor发送消息")
  32.   //向firstactor发送消息
  33.   firstactor!"test"
  34.   firstactor! 123
  35.   //关闭ActorSystem，停止所有Acotr运行
  36.   system.shutdown()
  37. }

代码运行结果：

  1. [INFO] [04/02/2016 21:51:34.440] [main] [ActorSystem(MyActorSystem)] 准备向firstactor发送消息
  2. [INFO] [04/02/2016 21:51:34.441] [MyActorSystem-akka.actor.default-dispatcher-4] [akka://MyActorSystem/user/firstActor/myActor] received test
  3. [INFO] [04/02/2016 21:51:34.441] [MyActorSystem-akka.actor.default-dispatcher-2] [akka://MyActorSystem/user/firstActor] received test
  4. [INFO] [04/02/2016 21:51:34.441] [MyActorSystem-akka.actor.default-dispatcher-2] [akka://MyActorSystem/user/firstActor] received 123
  5. [INFO] [04/02/2016 21:51:34.441] [MyActorSystem-akka.actor.default-dispatcher-4] [akka://MyActorSystem/user/firstActor/myActor] received unknown message
  6. [INFO] [04/02/2016 21:51:34.446] [MyActorSystem-akka.actor.default-dispatcher-4] [akka://MyActorSystem/user/firstActor/myActor] postStop In MyActor
  7. [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

  1. /*
  2. *停止Actor:context.stop方法
  3. */
  4. object Example_11 extends App{
  5.   import akka.actor.Actor
  6.   import akka.actor.ActorSystem
  7.   import akka.actor.Props
  8.   class FirstActor extends Actor with ActorLogging{
  9.     var child:ActorRef = context.actorOf(Props[MyActor], name = "myActor")
  10.     def receive = {
  11.       case "stop"=>context.stop(child)
  12.       case x =>{
  13.         //向MyActor发送消息
  14.         child ! x
  15.         log.info("received "+x)
  16.       }
  17.     }
  18.     override def postStop(): Unit = {
  19.       log.info("postStop In FirstActor")
  20.     }
  21.   }
  22.   class MyActor extends Actor with ActorLogging{
  23.     def receive = {
  24.       case "test" => log.info("received test");
  25.       case _      => log.info("received unknown message");
  26.     }
  27.     override def postStop(): Unit = {
  28.       log.info("postStop In MyActor")
  29.     }
  30.   }
  31.   val system = ActorSystem("MyActorSystem")
  32.   val systemLog=system.log
  33.   //创建FirstActor对象
  34.   val firstactor = system.actorOf(Props[FirstActor], name = "firstActor")
  35.   systemLog.info("准备向firstactor发送消息")
  36.   //向firstactor发送消息
  37.   firstactor!"test"
  38.   firstactor! 123
  39.   firstactor!"stop"
  40. }

代码运行结果：

  1. [INFO] [04/02/2016 22:02:48.760] [main] [ActorSystem(MyActorSystem)] 准备向firstactor发送消息
  2. [INFO] [04/02/2016 22:02:48.761] [MyActorSystem-akka.actor.default-dispatcher-5] [akka://MyActorSystem/user/firstActor/myActor] received test
  3. [INFO] [04/02/2016 22:02:48.761] [MyActorSystem-akka.actor.default-dispatcher-2] [akka://MyActorSystem/user/firstActor] received test
  4. [INFO] [04/02/2016 22:02:48.762] [MyActorSystem-akka.actor.default-dispatcher-2] [akka://MyActorSystem/user/firstActor] received 123
  5. [INFO] [04/02/2016 22:02:48.762] [MyActorSystem-akka.actor.default-dispatcher-5] [akka://MyActorSystem/user/firstActor/myActor] received unknown message
  6. [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

  1. class FirstActor extends Actor with ActorLogging{
  2.     var child:ActorRef = context.actorOf(Props[MyActor], name = "myActor")
  3.     def receive = {
  4.       case "stop"=>context.stop(child)
  5.       case x =>{
  6.         //向MyActor发送消息
  7.         child ! x
  8.         log.info("received "+x)
  9.       }
  10.     }
  11.     override def postStop(): Unit = {
  12.       log.info("postStop In FirstActor")
  13.     }
  14.   }

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
Akka并发编程——第五节：Actor模型（四） - 图1
（3）通过akka.actor.PoisonPill消息停止Actor的运行

  1. /*
  2. *停止Actor:使用akka.actor.PoisonPill
  3. */
  4. object Example_12 extends App{
  5.   import akka.actor.Actor
  6.   import akka.actor.ActorSystem
  7.   import akka.actor.Props
  8.   import akka.actor.PoisonPill
  9.   class FirstActor extends Actor with ActorLogging{
  10.     var child:ActorRef = context.actorOf(Props[MyActor], name = "myActor")
  11.     def receive = {
  12.       //向child发送PoisonPill停止其运行
  13.       case "stop"=>child!PoisonPill
  14.       case x =>{
  15.         //向MyActor发送消息
  16.         child ! x
  17.         log.info("received "+x)
  18.       }
  19.     }
  20.     override def postStop(): Unit = {
  21.       log.info("postStop In FirstActor")
  22.     }
  23.   }
  24.   class MyActor extends Actor with ActorLogging{
  25.     def receive = {
  26.       case "test" => log.info("received test");
  27.       case _      => log.info("received unknown message");
  28.     }
  29.     override def postStop(): Unit = {
  30.       log.info("postStop In MyActor")
  31.     }
  32.   }
  33.   val system = ActorSystem("MyActorSystem")
  34.   val systemLog=system.log
  35.   //创建FirstActor对象
  36.   val firstactor = system.actorOf(Props[FirstActor], name = "firstActor")
  37.   systemLog.info("准备向firstactor发送消息")
  38.   //向firstactor发送消息
  39.   firstactor!"test"
  40.   firstactor! 123
  41.   firstactor!"stop"
  42. }

代码运行结果：

  1. [INFO] [04/02/2016 22:12:09.947] [main] [ActorSystem(MyActorSystem)] 准备向firstactor发送消息
  2. [INFO] [04/02/2016 22:12:09.947] [MyActorSystem-akka.actor.default-dispatcher-2] [akka://MyActorSystem/user/firstActor/myActor] received test
  3. [INFO] [04/02/2016 22:12:09.947] [MyActorSystem-akka.actor.default-dispatcher-4] [akka://MyActorSystem/user/firstActor] received test
  4. [INFO] [04/02/2016 22:12:09.947] [MyActorSystem-akka.actor.default-dispatcher-4] [akka://MyActorSystem/user/firstActor] received 123
  5. [INFO] [04/02/2016 22:12:09.947] [MyActorSystem-akka.actor.default-dispatcher-2] [akka://MyActorSystem/user/firstActor/myActor] received unknown message
  6. [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

  1. //向child发送PoisonPill停止其运行
  2. 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