如何开始一个Scala akka演员

下面的类在新HelloWorld行导致错误：

Exception in thread "main" akka.actor.ActorInitializationException: You cannot create an instance of [HelloWorld] explicitly using the constructor (new). You have to use one of the 'actorOf' factory methods to create a new actor. See the documentation.
  at akka.actor.ActorInitializationException$.apply(Actor.scala:219)
  at akka.actor.Actor$class.$init$(Actor.scala:436)
  at HelloWorld.<init>(HelloWorld.scala:4)
  at Driver$.main(HelloWorld.scala:38)
  at Driver.main(HelloWorld.scala)

下面的HelloWorld应该如何实现

阅读其他Scala文档时，需要在扩展Actor的类中定义act方法，然后在此类上调用start方法，是否有理由使用actorOf而不是定义act方法

以下课程摘自Scala-akka文档：

---

如果要使用主类，请执行以下操作：

import akka.actor.{ActorSystem, Props}
object Driver extends App {    
    val system = ActorSystem("System")
    val hw = system.actorOf(Props[HelloWorld], name = "hw")
}

这将创建一个新的actor系统，然后使用该actor系统创建HelloWorld actor

您也可以按照akka说明进行操作：

---

将Akka.Main设置为主类，并将程序“com.example.HelloWorld”作为参数。

您需要编辑Main，如下所示。第二，在第5行中，您需要将其更改为

context.actorOf（Props（新迎宾者））

。这是因为您的

Greeter

没有定义

apply

函数，因此您需要自己手动创建Greeter对象

工作代码如下：

import akka.actor.ActorSystem

class HelloWorld extends Actor {

  override def preStart(): Unit = {
    // create the greeter actor
    val greeter = context.actorOf(Props(new Greeter), "greeter")//line 5
    // 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)
  }

  object Greeter {   

    case object Greet
    case object Done


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


}

object Driver {

    def main(args: Array[String]) {
      val system = ActorSystem("Main")
      val ac = system.actorOf(Props[HelloWorld])
    }

}

---

我认为你不需要为Greeter添加新的关键字。我相信道具已经为你做到了。如果有新的act（）和start（）属于旧的和不推荐使用的Scala actors，则Akka是另一个actor实现，请参阅位于的文档。@RolandKuhn感谢链接，经过一些挖掘，此文档证明是有用的：

import akka.actor.{ActorSystem, Props}
object Driver extends App {    
    val system = ActorSystem("System")
    val hw = system.actorOf(Props[HelloWorld], name = "hw")
}

import akka.actor.ActorSystem

class HelloWorld extends Actor {

  override def preStart(): Unit = {
    // create the greeter actor
    val greeter = context.actorOf(Props(new Greeter), "greeter")//line 5
    // 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)
  }

  object Greeter {   

    case object Greet
    case object Done


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


}

object Driver {

    def main(args: Array[String]) {
      val system = ActorSystem("Main")
      val ac = system.actorOf(Props[HelloWorld])
    }

}

val greeter = context.actorOf(Props(new Greeter), "greeter")//line 5