Question

如果可能的话，我正在解决一个我真的想要解决的错误，而不是简单地找到解决办法。

这是我的代码：

import akka.actor._
import concurrent.duration._

sealed trait Message
case class ReturnInfluenceMessage(source: ActorRef) extends Message
case class SetInfluences(source: ActorRef) extends Message
case class Start(period:Int) extends Message
case object GetInfluence extends Message
case object Stop extends Message
case object TickMessage extends Message

class Listener extends Actor {
    def receive = {
        case _ =>
            println("Listener: received something\n")
    }
}

class Entity extends Actor {
    val router = context.actorOf(Props[Router], name = "Router")

    def receive = {
        case rim @ ReturnInfluenceMessage(source) =>
            source ! rim

        case msg =>
            shadow ! msg
    }
}

class Router extends Actor {
    val pulser = context.actorOf(Props[Pulser], name = "Pulser")
    //more children

    def receive = {
        case rim @ ReturnInfluenceMessage(source) =>
            context.parent ! rim

        case msg =>
            context.children foreach (_.forward(msg))
    }
}

class Pulser extends Actor {
    val clock = context.actorOf(Props[Clock], name = "Clock")

    def receive = {
        case TickMessage =>
            println ("Emission_Unit: received Tickmessage!\n")

        case _  => 
            println ("Emission_Unit: received something\n")
    }
}

class Clock extends Actor { 
    def receive = ready

    def ready:Receive = {
        case Start(period) => {
            println ("Heartbeat: Start")
            context.become(running(period) orElse ready)
            context.system.scheduler.scheduleOnce(period milliseconds, self, TickMessage)
        }
    }

    def running(period:Int):Receive = {
        case TickMessage => {
            context.parent ! TickMessage
            context.system.scheduler.scheduleOnce(period milliseconds, self, TickMessage)
        }

        case Stop =>
            println("Clock: stopping")
            context.unbecome()
    }
}

object Main extends App {
    val system = akka.actor.ActorSystem("mySystem")
    val abel = system.actorOf(Props[Listener], name = "Listener")
    val cain = system.actorOf(Props[Entity], name = "Entity")

    import system.dispatcher
    system.scheduler.scheduleOnce(...)
    //do something irrelevant
}

这不编译。似乎编译器无法识别行上的period变量：

context.system.scheduler.scheduleOnce(period milliseconds, self, TickMessage)

这是错误：

[info] Compiling 1 Scala source to /home/yuggoth/witchdoctor/fff/target/scala-2.11/classes...
[error] /home/yuggoth/witchdoctor/fff/src/main/scala/prjt11.scala:64: Cannot find an implicit ExecutionContext. You might pass
[error] an (implicit ec: ExecutionContext) parameter to your method
[error] or import scala.concurrent.ExecutionContext.Implicits.global.
[error]             context.system.scheduler.scheduleOnce(period milliseconds, self, TickMessage)
[error]                                                  ^
[error] /home/yuggoth/witchdoctor/fff/src/main/scala/prjt11.scala:71: Cannot find an implicit ExecutionContext. You might pass
[error] an (implicit ec: ExecutionContext) parameter to your method
[error] or import scala.concurrent.ExecutionContext.Implicits.global.
[error]             context.system.scheduler.scheduleOnce(period milliseconds, self, TickMessage)
[error]                                                  ^
[error] two errors found
[error] (compile:compile) Compilation failed
[error] Total time: 4 s, completed Sep 2, 2014 4:46:52 PM

我在这里要做的就是让Clock发送TickMessage到parent Pulser。我尝试使用我刚学到的状态设置而没有状态变量。

Answer 1

尝试：

import scala.concurrent.ExecutionContext.Implicits.global

这对我有用

Answer 2

编译器告诉您方法context.system.scheduler.scheduleOnce需要隐式参数(implicit ec: ExecutionContext)。

因此，您需要提供ExecutionContext或导入可使implicit ExecutionContext可见的范围。

快速查看akka doc告诉您使用：

import system.dispatcher

他们没有告诉你的是之前要定义system，因为它不是一个包而是一个对象：

val system = akka.actor.ActorSystem("system")

未找到状态设置中的参数

2 个答案: