Akka 快速入門
阿新 • • 發佈：2018-12-25
Akka的優點太多，高效能、高可靠、高併發、分散式、可容錯、可擴充套件、事件驅動，不一一敘述。不同版本的API差異很大，本文程式碼執行在 Scala
2.10.3 和 Akka 2.3.2 之上。
<dependency>
<groupId>com.typesafe.akka</groupId>
<artifactId>akka-actor_2.10</artifactId>
<version>2.3.2</version>
</dependency>
<dependency>
<groupId
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定義
定義Actor很簡單，繼承 akka.actor.Actor ，實現receive方法即可。
class Hello extends Actor {
def receive = {
case msg: String => println("hello " + msg)
case
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啟動
建立Actor例項需要通過 ActorSystem 。
val system = ActorSystem("HelloSystem")
val hello = system.actorOf(Props[Hello], name = "hello")
val hello1 = system.actorOf(Props[Hello])
val hello2 = system.actorOf(Props(new Hello()))
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如果要在 Actor 中繼續建立子 Actor，需要使用內建的 ActorContext 物件。
context.actorOf(Props[children], name = "children")
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如果要建立遠端 Actor，需要通過 actorSelection 方法，原 actorFor 方法不再使用。
context.actorSelection("akka.tcp://[email protected]:5150/user/RemoteActor")
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發訊息
巨簡單，就是一個!，可以傳送任意型別的訊息，此訊息是非同步的。
hello ! "bruce"
hello ! 10086
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同步訊息的傳送需要使用 Future 物件。
implicit val timeout = Timeout(5 seconds)
val future = hello ? "sha"
val result = Await.result(future, timeout.duration).asInstanceOf[String]
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停止
有兩種方式停止一個Actor。
一種是通過內部 ActorContext.stop() 方法，該方法會將 children actor 逐層殺掉後，再自刎。
def receive = {
case "stop" => context.stop(self)
...
}
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另一種是外部喂毒藥，通過 ActorRef.tell() 方法實現。後一個引數是向誰reply，這裡顯然不需要，傳空。
hello.tell(PoisonPill.getInstance, ActorRef.noSender);
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哼哈示例
哼哈二將本是兩位佛寺的門神俗稱，是執金剛神的一種。明代小說《封神演義》作者陳仲琳據此附會兩員神將，形象威武凶猛。一名鄭倫，能鼻哼白氣制敵；一名陳奇，能口哈黃氣擒將。
object HengHa extends App {
val system = ActorSystem("HengHaSystem")
val ha = system.actorOf(Props[Ha], name = "ha")
val heng = system.actorOf(Props(new Heng(ha)), name = "heng")
heng ! "start"
}
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class Heng(ha: ActorRef) extends Actor {
def receive = {
case "start" => ha ! "heng"
case "ha" =>
println("哈")
ha ! "heng"
case _ => println("heng what?")
}
}
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class Ha extends Actor {
def receive = {
case "heng" =>
println("哼")
sender ! "ha"
case _ => println("ha what?")
}
}
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Run 起來，結果：
哼
哈
哼
哈
哼
...
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遠端示例
local工程
application.conf
akka {
loglevel = "DEBUG"
actor {
provider = "akka.remote.RemoteActorRefProvider"
}
remote {
enabled-transports = ["akka.remote.netty.tcp"]
netty.tcp {
hostname = "127.0.0.1"
port = 5155
}
}
}
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object Local extends App {
val system = ActorSystem("LocalSystem")
val localActor = system.actorOf(Props[LocalActor], name = "LocalActor") // the local actor
localActor ! "START" // start the action
}
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class LocalActor extends Actor {
// create the remote actor
val remote = context.actorSelection("akka.tcp://[email protected]:5150/user/RemoteActor")
var counter = 0
def receive = {
case "START" =>
remote ! "Hello from the LocalActor"
case msg: String =>
println(s"LocalActor received message: '$msg'")
if (counter < 5) {
sender ! "Hello back to you"
counter += 1
}
}
}
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remote工程
application.conf
akka {
loglevel = "DEBUG"
actor {
provider = "akka.remote.RemoteActorRefProvider"
}
remote {
enabled-transports = ["akka.remote.netty.tcp"]
netty.tcp {
hostname = "127.0.0.1"
port = 5150
}
}
}
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object HelloRemote extends App {
val system = ActorSystem("HelloRemoteSystem")
val remoteActor = system.actorOf(Props[RemoteActor], name = "RemoteActor")
remoteActor ! "The RemoteActor is alive"
}
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class RemoteActor extends Actor {
def receive = {
case msg: String =>
println(s"RemoteActor received message '$msg'")
sender ! "Hello from the RemoteActor"
}
}
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原文連結：http://ibruce.info/2014/05/20/hello-akka/