如何开始Scala akka演员

发布时间：2020-12-16 18:45:01 所属栏目：安全来源：网络整理

导读：下面的类在新的HelloWorld行引起错误： 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 met

下面的类在新的HelloWorld行引起错误：

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)

所以我试试：val hw = actorOf(new HelloWorld)
但这会导致编译器错误：

not found: value actorOf

HelloWorld如何实现？

读取其他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？

下面的课程来自Scala akka docs http://doc.akka.io/docs/akka/2.2.0/scala.html：

import akka.actor.Actor
import akka.actor.Actor._
import akka.actor.Props

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)
  }

  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]) {
      new HelloWorld
    }

}

解决方法

您需要编辑主页,如下所示.其次,在第5行中,您需要将其更改为context.actorOf(Props(new Greeter)).这是因为您的Greeter没有定义应用函数,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])
    }

}

（编辑：李大同）

【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容!