Akka併發程式設計——第五節：Actor模型（四）
阿新 • • 發佈：2018-12-25
本節主要內容：
1. 停止Actor
1. 停止Actor
（1）通過ActorSystem.shutdown方法停止所有 Actor的執行
/*
*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" 程式碼執行結果：
[INFO] [04/02/2016 21:51:34.440] [main] [ActorSystem(MyActorSystem)] 準備向firstactor傳送訊息
[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）通過context.stop方法停止Actor的執行
/*
*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傳送訊息
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
//建立FirstActor物件
val firstactor = system.actorOf(Props[FirstActor], name = "firstActor")
systemLog.info("準備向firstactor傳送訊息")
//向firstactor傳送訊息
firstactor!"test"
firstactor! 123
firstactor!"stop"
}程式碼執行結果：
[INFO] [04/02/2016 22:02:48.760] [main] [ActorSystem(MyActorSystem)] 準備向firstactor傳送訊息
[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
程式碼的重點為
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傳送訊息
child ! x
log.info("received "+x)
}
}
override def postStop(): Unit = {
log.info("postStop In FirstActor")
}
}中的case “stop”=>context.stop(child)，直接通過context.stop方法停止Actor的執行。注意程式中並沒有使用system.shutdown方法，因此整個程式的不會停止，如下圖所示
（3）通過akka.actor.PoisonPill訊息停止Actor的執行
/*
*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傳送PoisonPill停止其執行
case "stop"=>child!PoisonPill
case x =>{
//向MyActor傳送訊息
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
//建立FirstActor物件
val firstactor = system.actorOf(Props[FirstActor], name = "firstActor")
systemLog.info("準備向firstactor傳送訊息")
//向firstactor傳送訊息
firstactor!"test"
firstactor! 123
firstactor!"stop"
}程式碼執行結果：
[INFO] [04/02/2016 22:12:09.947] [main] [ActorSystem(MyActorSystem)] 準備向firstactor傳送訊息
[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程式碼與Exampel_11中的不同之處在於
//向child傳送PoisonPill停止其執行
case "stop"=>child!PoisonPill它使用不是context.stop方法，而是向MyActor傳送了PoisonPill訊息，其它程式碼不變。
還有一種gracefulStop方法可以停止Actor的執行，這部分內容等了解完Future類的作用原理之後再來討論
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