Child Actor

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

object AkkaMain {
  object Parent {
    def props() = Props(new Parent())

    case class CreateChild(name: String)
    case class TellChild(message: String)
  }

  import Parent.{CreateChild, TellChild}

  class Parent extends Actor {
    override def receive: Receive = {
      case CreateChild(name) =>
        println(s"${self.path} creating child")
        val childRef = context.actorOf(Child.props(), name)
        context.become(withChild(childRef))
    }

    def withChild(childRef: ActorRef): Receive = {
      case TellChild(message) =>
       if (childRef != null) childRef forward message
    }
  }

  object Child {
    def props() = Props(new Child())
  }

  class Child extends Actor {
    override def receive: Receive = { case message =>
      println(s"${self.path} I got: $message")
    }
  }

  def main(args: Array[String]): Unit = {
    val actorSystem: ActorSystem = ActorSystem(name = "actorDemo")

    import Parent._
    val parentActor = actorSystem.actorOf(Parent.props(), "parent")
    parentActor ! CreateChild("child")
    parentActor ! TellChild("hey Kid!")

    val childSelection = actorSystem.actorSelection("/user/parent/child")
    childSelection ! "I found you"
  }
}

 

결과

akka://actorDemo/user/parent creating child
akka://actorDemo/user/parent/child I got: hey Kid!
akka://actorDemo/user/parent/child I got: I found you

 

설명

• context.actorOf() 로 child actor 생성
• parent / child actor 로 tree heirachy 를 구성할 수 있다.
• top-level supervisor (guardians)
  • / : the root guardian
  • /system: logging 등 ..
  • /user: application 에서 생성하는 actor 
• actorSystem.actorSelection() 으로 actor 에 접근할 수 있다.
• 주의 사항 
  • parent actor 의 상태 변수나 parent `this` 를 절대 child actor 로 전달하지 말라!
  • actor 의 상태는 override def receive: Receive 메소드를 통해서만 관리되어야 한다.