akka开发（一）HelloWorld

package com.hfi.helloakka;

import akka.actor.ActorRef;
import akka.actor.Props;
import akka.actor.UntypedActor;

public class HelloWorld extends UntypedActor {
     
      @Override
      public void preStart() {
        // create the greeter actor
        final ActorRef greeter =
            getContext().actorOf(Props.create(Greeter.class), "greeter");
        // tell it to perform the greeting
        greeter.tell(Greeter.Msg.GREET, getSelf());
      }
     
      @Override
      public void onReceive(Object msg) {
        if (msg == Greeter.Msg.DONE) {
          // when the greeter is done, stop this actor and with it the application
          getContext().stop(getSelf());
        } else unhandled(msg);
      }
    }

package com.hfi.helloakka;

import akka.actor.UntypedActor;

public class Greeter extends UntypedActor {
      
      public static enum Msg {
        GREET, DONE;
      }
      
      @Override
      public void onReceive(Object msg) {
        if (msg == Msg.GREET) {
          System.out.println("Hello World!");
          getSender().tell(Msg.DONE, getSelf());
        } else unhandled(msg);
      }
      
    }

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.hfi</groupId>
  <artifactId>helloakka</artifactId>
  <packaging>war</packaging>
  <version>0.0.1-SNAPSHOT</version>
  <name>helloakka Maven Webapp</name>
  <url>http://maven.apache.org</url>
  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.scala-lang</groupId>
        <artifactId>scala-library</artifactId>
        <version>2.10.2</version>
    </dependency>
    <dependency>
          <groupId>com.typesafe.akka</groupId>
          <artifactId>akka-actor_2.10</artifactId>
          <version>2.2.5</version>
    </dependency>
  </dependencies>
  <build>
    <finalName>helloakka</finalName>
  </build>
</project>

可能遇到的问题：

java.lang.NoClassDefFoundError: scala/collection/GenTraversableOnce$class

用的akka包跟依赖的scala包版本不一致导致（貌似scala不向下兼容它的旧版本），笔者一开始用的2.11.7报错，换成pom中的2.10.2后（到akka-2.2.5.zip中看的版本号）程序就跑起来了。  参考了：http://www.jianshu.com/p/59733597d448