Akka Actor发送消息示例详解 _Akka开发教程

本文概述

Akka Actor发送消息
Actor tell()方法示例
Akka Actor tell()方法示例2
2)Akka Actor询问方法
Akka Actor询问方法示例
Akka Actor ask()方法示例2
Akka Actor询问方法示例3

在Akka中, Actor通过发送和接收消息来相互交流。
Akka Actor发送消息Akka提供了两个预定义的方法tell()和ask()进行消息交换。Actor可以通过以下方法将消息发送给另一个Actor。
1)Akka Actor tell()方法
【Akka Actor发送消息示例详解】它用于异步发送消息。它不会等待并阻止线程发送消息。它适用于” 忘火” 方法。你也可以使用！ (bang)感叹号发送消息。这是发送消息的首选方式。它提供了最佳的并发性和可伸缩性。
如果从Actor内部调用此方法, 则发送Actor的引用将与消息一起隐式传递。
如果从不是Actor的实例调用此方法, 则默认情况下, 发送者将是deadLetters actor引用。
Actor tell()方法示例

import akka.actor.{Actor, ActorSystem, Props}; class ActorExample extends Actor{ def receive = { case message:String => println("Message received: "+message+ " from - "+ self.path.name); println("sender:"+ sender()); // returns ActorRef } }object ActorExample{ def main(args:Array[String]){ val actorSystem = ActorSystem("ActorSystem"); val actor = actorSystem.actorOf(Props[ActorExample], "RootActor"); actor ! "Hello"// Sending message by using ! actor.tell("Hello", null); // Sending message by using tell() method // Sender is not passed here. } }

输出

Message received: Hello from - RootActor sender:Actor[akka://ActorSystem/deadLetters]// ActorRef refers to deadLetters Message received: Hello from - RootActor sender:Actor[akka://ActorSystem/deadLetters] // ActorRef refers to deadLetters

Akka Actor tell()方法示例2

import akka.actor.{Actor, ActorSystem, Props}; class ActorExample extends Actor{ def receive = { case message:String => println("Message received: "+message+ " from - "+ self.path.name); println("Sender: "+sender()) var child = context.actorOf(Props[Actor2], "ChildActor"); child ! "Hello"} }class Actor2 extends Actor{ def receive = { case message:String => println("Message received: "+message+ " from - "+ self.path.name); println("Sender: "+sender()); } }object ActorExample{ def main(args:Array[String]){ val actorSystem = ActorSystem("ActorSystem"); val actor = actorSystem.actorOf(Props[ActorExample], "RootActor"); actor ! "Hello" } }

输出

Message received: Hello from - RootActor Sender: Actor[akka://ActorSystem/deadLetters] // Called from outside Actor Message received: Hello from - ChildActor Sender: Actor[akka://ActorSystem/user/RootActor#1451914889] // Called from within Actor

2)Akka Actor询问方法在akka中, ask是一种模式, 涉及参与者和期货。 Ask用于异步发送消息, 它返回一个Future, 表示可能的答复。如果Actor没有回复并完成未来, 它将在超时期限后过期。超时时间过后, 它将引发TimeoutException。你可以使用其中一个吗？ (问号)或ask()发送消息。
如果你要响应, 则应始终倾向于使用Tell方法来提高性能, 而Ask方法则要优先。
Akka Actor询问方法示例

import akka.actor.{Actor, ActorSystem, Props}; import akka.util.Timeout; import scala.concurrent.Await import akka.pattern.ask import scala.concurrent.duration._class ActorExample extends Actor{ def receive = { case message:String => println("Message recieved: "+message); } }object ActorExample{ def main(args:Array[String]){ val actorSystem = ActorSystem("ActorSystem"); val actor = actorSystem.actorOf(Props[ActorExample], "RootActor"); implicit val timeout = Timeout(2 seconds); val future = actor ? "Hello"; val result = Await.result(future, timeout.duration); println(result); } }

输出

Message recieved: Hello Exception in thread "main" java.util.concurrent.TimeoutException: Futures timed out after [2 seconds]

Akka Actor ask()方法示例2

import akka.actor.{Actor, ActorSystem, Props, ActorRef}; import akka.util.Timeout; import scala.concurrent.Await import akka.pattern.ask import scala.concurrent.duration._class ActorExample extends Actor{ def receive = { case message:String => println("Message received: "+message+" from outside actor instance"); println("Replaying"); val senderName = sender(); senderName ! "Hello, I got your message."; // Replying message } }object ActorExample{ def main(args:Array[String]){ val actorSystem = ActorSystem("ActorSystem"); val actor = actorSystem.actorOf(Props[ActorExample], "RootActor"); implicit val timeout = Timeout(10 seconds); val future = actor ? "Hello"; val result = Await.result(future, timeout.duration); println("Message received: "+result); } }

输出

Message received: Hello from outside actor instance Replaying Message received: Hello, I got your message.

Akka Actor询问方法示例3

import akka.actor.{Actor, ActorSystem, Props}; import akka.util.Timeout; import scala.concurrent.Await import akka.pattern.ask import scala.concurrent.duration._class ActorExample extends Actor{ def receive = { case message:String => println("Message received: "+message+" from outside actor instance"); Thread.sleep(5000); // actor thread is sleeping println("Replaying"); val senderName = sender(); senderName ! "Hello, I got your message."; // Replying message } }object ActorExample{ def main(args:Array[String]){ val actorSystem = ActorSystem("ActorSystem"); val actor = actorSystem.actorOf(Props[ActorExample], "RootActor"); implicit val timeout = Timeout(2 seconds); val future = actor ? "Hello"; val result = Await.result(future, timeout.duration); println("Message received: "+result); } }

输出

Message received: Hello from outside actor instance Exception in thread "main" java.util.concurrent.TimeoutException: Futures timed out after [2 seconds]