Akka学习笔记（一）：创建Hello World工程

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原文转自：http://blog.csdn.net/wsscy2004/article/details/38233091

Akka学习笔记（一）：创建Hello World工程

创建工程

使用IDEA,创建SBT工程，在build.sbt中添加akka依赖：

name := "My Project"version := "1.0"scalaVersion := "2.10.4"resolvers += "Typesafe Repository" at "http://repo.typesafe.com/typesafe/releases/"libraryDependencies +=  "com.typesafe.akka" %% "akka-actor" % "2.3.4"

如果SBT版本低于0.12,需要更改依赖为：

libraryDependencies +=  "com.typesafe.akka" % "akka-actor_2.10" % "2.3.4"

其他IDE,构建方式，请看here

Hello World

完整代码可以在这里下载

HelloWorld.scala

我们创建HelloWorld.scala,代码如下：

class HelloWorld extends Actor {  override def preStart(): Unit = {    // create the greeter actor    val greeter = context.actorOf(Props[Greeter], "greeter")    // tell it to perform the greeting    greeter ! Greeter.Greet  }  def receive = {    // when the greeter is done, stop this actor and with it the application    case Greeter.Done => context.stop(self)  }}

HelloWorld是我们这个应用的中心(main),它会启动和关闭所有actor(Greeter)

Greeter.scala

object Greeter {  case object Greet  case object Done}class Greeter extends Actor {  def receive = {    case Greeter.Greet =>      println("Hello World!")      sender() ! Greeter.Done  }}

Greeter的内容很简单，一旦它被创建，等待接受消息，打印Hello World!，并告诉调用者Greeter.Done

Main.scala

让我们运行这个程序吧，很简单，指定负责调度的Actor:HelloWorld就可以了：

object Main {  def main(args: Array[String]): Unit = {    akka.Main.main(Array(classOf[HelloWorld].getName))  }}

运行：

Hello World![INFO] [07/25/2014 15:11:43.147] [Main-akka.actor.default-dispatcher-4] [akka://Main/user/app-terminator] application supervisor has terminated, shutting down

如何发布和使用Akka程序

有两种方式：

当做jar包使用
作为单独的服务，使用Akka Microkernel，详见here

Akka Microkernel

大致就是，把依赖包放到lib/*,通过启动类如(HelloKernel)启动：

bin/akka sample.kernel.hello.HelloKernel

helloKernel代码如下：

package sample.kernel.helloimport akka.actor.{ Actor, ActorSystem, Props }import akka.kernel.Bootablecase object Startclass HelloActor extends Actor {  val worldActor = context.actorOf(Props[WorldActor])  def receive = {    case Start => worldActor ! "Hello"    case message: String =>      println("Received message '%s'" format message)  }}class WorldActor extends Actor {  def receive = {    case message: String => sender() ! (message.toUpperCase + " world!")  }} //启动类，需要继承Bootableclass HelloKernel extends Bootable {  val system = ActorSystem("hellokernel")  def startup = {    system.actorOf(Props[HelloActor]) ! Start  }  def shutdown = {    system.shutdown()  }}

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