Question

您好我是Scala的新手，我无法弄清楚如何在第二个actor中存储actor引用，以便稍后发送消息。在我的代码中，我尝试向一个actor发送测试消息。当它收到此消息时，它应该将引用（OutputChannel）存储到第二个actor，稍后应该能够向第二个actor发送消息。我不想使用reply（），因为我只需要在调用响应时才需要发送消息。这是代码。谢谢你的帮助！

import scala.actors.Actor
import scala.actors.Actor._
import scala.collection.mutable.ArrayBuffer 
import scala.actors.OutputChannel

object testactors {

    case object TestMessage
    case object Respond

    class TestActor(name: String) extends Actor {
        private var source : ArrayBuffer[OutputChannel[Any]] = new ArrayBuffer

        def act() {
            loop {
                react{
                    case TestMessage =>
                        println("i received a TestMessage " + name)
                        source += sender
                    case Respond =>
                        println("i received a ResponseMessage " + name)
                }
            }
        }

        def sendMessage(dest: Actor) = dest ! TestMessage

        def respond = {
            println("responding... " + name)
            source(0) ! Respond
        }
    }


    def main(args: Array[String]) {
        val actor1 = new TestActor("one")
        actor1.start

        val actor2 = new TestActor("two")
        actor2.start

        actor1.sendMessage(actor2)

        Thread.sleep(5000)

        actor2.respond
    }
}

Answer 1

1. 您可以创建集中式actor注册表。为了避免重新发明轮子，你可以使用一个好的现有实现 - Akka's Actor Registry （或者，至少，从中受到启发）。

2 您可以避免使用可更改的actor引用列表将其传递给react循环：

case class AddActor(actor: Actor)
case object NotifyAll

class StatefulActor extends Actor {

  override def act = loop(Nil)

  def loop(actors: List[Actor]):Unit = {
    react {
      case AddActor(actor) => println("Added new actor")
        loop(actor :: actors)
      case NotifyAll => println("Notifying actors: " + actors)
        actors.foreach(_ ! "Hi!")
        loop(actors)
      case unknown => println("Unknown message: " + unknown)    
        loop(actors)
    }
  }

}

Answer 2

这样做的一种方法是创建一个Actor Factory，用于存储可以从任何地方抓取的actor。

import scala.actors.Actor
import scala.actors.Actor._
import scala.collection.mutable._

消息可以是对象（没有“有效负载”），也可以是包含数据的类

abstract class Message
case object MessageType1 extends Message
case class MessageType2(str:String) extends Message

以下是一些演员类型。 Actor2实例“在运行中”实例化，并存储在ActorFactory中以供以后使用，就像在主

中显式声明的Actor1实例一样

class MyActor1 extends Actor {
    def act() {
        loop {
            react {
                case MessageType1 => 
                    println("MessageType1 received")
                    ActorFactory.getActor2("B") ! MessageType2("Hello")
                case _ =>
            }
        }
    }
}

class MyActor2 extends Actor {
    def act() {
        loop {
            react {
                case MessageType2(theString) =>
                    println(theString+" from actor 2 instance")
                case _ =>
            }
        }
    }
}

以下ActorFactory创建并存储actor。在这里，您可以创建一个actor类型的多个实例，并按名称存储。

object ActorFactory {
    val actorMap = new HashMap[String,Actor] with SynchronizedMap[String,Actor]

    def getActor1(symbol:String): Actor = {
        val actor = actorMap.getOrElseUpdate(symbol,new MyActor1().start)
        actor
    }

    def getActor2(symbol:String): Actor = {
        val actor = actorMap.getOrElseUpdate(symbol,new MyActor2().start)
        actor
    }
}

object Test {

    def main(args : Array[String]) {                    

        val actor1 = ActorFactory.getActor1("A")
        actor1 ! MessageType1

    }

}

这是

的输出

MessageType1 received
Hello from actor 2 instance

如何存储scala actor引用？

2 个答案: