IntelliJ IDEA使用SBT构建一个AKKA Scala程序

1、下载安装 IntelliJ IDEA

2、下载安装 Scala

3、在IntelliJ IDEA中安装Scala插件

4、创建工程

5、设置build.sbt

在项目中的build.sbt中追加下图所示的resolvers和libraryDependencies

resolvers += "Typesafe Repository" at "http://repo.typesafe.com/typesafe/releases/"

libraryDependencies += "com.typesafe.akka" % "akka-actor_2.11" % "2.3.4"

添加后，若当前电脑没有设置版本的akka，则会显示红线，保存后会自动下载akka

6、开始写代码

例子1

我们要做的设计是由一个 主 actor来启动整个计算过程，创建一组 工作 actor. 整个工作会被分割成具体的小段, 各小段会以round-robin的方式发送到不同的工作 actor. 主actor等待所有的工作actor完全各自的工作并将其回送的结果进行汇总。当计算完成以后，主actor将结果发送给 监听器 acotr, 由它来输出结果。

/**
  * Created by yangruimin on 2016/8/3.
  */

import java.util.concurrent.TimeUnit

import akka.actor._
import akka.routing.RoundRobinRouter

import scala.concurrent.duration.Duration

object Pi extends App {

  calculate(nrOfWorkers = 4, nrOfElements = 10000, nrOfMessages = 10000)

  sealed trait PiMessage
  case object Calculate extends PiMessage
  case class Work(start: Int, nrOfElements: Int) extends PiMessage
  case class Result(value: Double) extends PiMessage
  case class PiApproximation(pi: Double, duration: Duration)

  class Worker extends Actor {

    def calculatePiFor(start: Int, nrOfElements: Int): Double = {
      var acc = 0.0
      for (i ← start until (start + nrOfElements))
        acc += 4.0 * (1 - (i % 2) * 2) / (2 * i + 1)
      acc
    }

    def receive = {
      case Work(start, nrOfElements) ⇒
        sender ! Result(calculatePiFor(start, nrOfElements)) // perform the work
    }
  }

  class Master(nrOfWorkers: Int, nrOfMessages: Int, nrOfElements: Int, listener: ActorRef)
    extends Actor {

    var pi: Double = _
    var nrOfResults: Int = _
    val start: Long = System.currentTimeMillis

    val workerRouter = context.actorOf(
      Props[Worker].withRouter(RoundRobinRouter(nrOfWorkers)), name = "workerRouter")

    def receive = {
      case Calculate ⇒
        for (i ← 0 until nrOfMessages) workerRouter ! Work(i * nrOfElements, nrOfElements)
      case Result(value) ⇒
        pi += value
        nrOfResults += 1
        if (nrOfResults == nrOfMessages) {
          // Send the result to the listener
          listener ! PiApproximation(pi, duration = Duration.create(System.currentTimeMillis - start, TimeUnit.MILLISECONDS))
          // Stops this actor and all its supervised children
          context.stop(self)
        }
    }

  }

  class Listener extends Actor {
    def receive = {
      case PiApproximation(pi, duration) ⇒
        println("\n\tPi approximation: \t\t%s\n\tCalculation time: \t\t%s\n"
          .format(pi, duration))
        context.system.shutdown()
    }
  }


  def calculate(nrOfWorkers: Int, nrOfElements: Int, nrOfMessages: Int) {
    // Create an Akka system
    val system = ActorSystem("PiSystem")

    // create the result listener, which will print the result and shutdown the system
    val listener = system.actorOf(Props[Listener], name = "listener")

    // create the master
    val master = system.actorOf(Props(new Master(
      nrOfWorkers, nrOfMessages, nrOfElements, listener)),
      name = "master")

    // start the calculation
    master ! Calculate

  }
}

运行结果如下：

例子2

使用?标识符，从feature获取计算文件行数的的结果

import akka.actor.{Actor, ActorRef, ActorSystem, Props}

import scala.concurrent.Await

/**
  * Created by yangruimin on 2016/8/3.
  */
object Sample extends App
{

  import akka.util.Timeout
  import scala.concurrent.duration._
  import akka.pattern.ask
  import akka.dispatch.ExecutionContexts._

  implicit val ec = global

  override def main(args: Array[String])
  {
    val system = ActorSystem("System")
    val actor = system.actorOf(Props(new WordCounterActor("C:\\Users\\Administrator\\Desktop\\file.txt")))
    implicit val timeout = Timeout(25 seconds)
    val future = actor ? StartProcessFileMsg()
    val result = Await.result(future, timeout.duration)
    println("Total number of words " + result)
    system.shutdown
  }

  /**
    * main actor
    */
  case class StartProcessFileMsg()
  class WordCounterActor(filename: String) extends Actor
  {
    private var running = false
    private var totalLines = 0
    private var linesProcessed = 0
    private var result = 0
    private var fileSender: Option[ActorRef] = None

    def receive =
    {
      case StartProcessFileMsg() =>
      {
        if (running)
        {
          // println just used for example purposes;
          // Akka logger should be used instead
          println("Warning: duplicate start message received")
        } else
        {
          running = true
          fileSender = Some(sender) // save reference to process invoker
          import scala.io.Source._
          fromFile(filename).getLines.foreach
          { line =>
            context.actorOf(Props[StringCounterActor]) ! ProcessStringMsg(line)
            totalLines += 1
          }
        }
      }
      case StringProcessedMsg(words) =>
      {
        result += words
        linesProcessed += 1
        if (linesProcessed == totalLines)
        {
          fileSender.map(_ ! result) // provide result to process invoker
        }
      }
      case _ => println("message not recognized!")
    }
  }

  /**
    * secondary actor
    */
  case class ProcessStringMsg(string: String)
  case class StringProcessedMsg(words: Integer)
  class StringCounterActor extends Actor
  {
    def receive =
    {
      case ProcessStringMsg(string) =>
      {
        val wordsInLine = string.split(" ").length
        sender ! StringProcessedMsg(wordsInLine)
      }
      case _ => println("Error: message not recognized")
    }
  }
}

运行结果如下：

Demo源码：http://download.youkuaiyun.com/detail/lyyybz/9609243