接《Akka学习笔记：Actor消息处理-请求和响应(1)》

二、StudentActor对InitSignal消息作出反应，并且发送了QuoteRequest 消息给TeacherActor

四、StudentActor仅仅将QuoteResponse 作为日志打印到控制台/logger

　　为什么我将二、四结合起来写？因为这两个很简单，如果我将他们分开来写，你肯定会讨厌我的！

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　　第二块 - StudentActor接收来自DriverApp的InitSignal 消息，然后给TeacherActor发送一个QuoteRequest。

def receive = {  
    case InitSignal=> {
          teacherActorRef!QuoteRequest
    }
    ...
    ...

　　这就是第二步要做的！
　　第四块，StudentActor将从TeacherActor接收到的消息记到日志里面

代码如下：

case QuoteResponse(quoteString) => {  
      log.info ("Received QuoteResponse from Teacher")
      log.info(s"Printing from Student Actor $quoteString")
}

　　我同意你认为上面的代码看起来有点想伪代码。所以，StudentActor 的完整代码如下：

package me.rerun.akkanotes.messaging.requestresponse

import akka.actor.Actor  
import akka.actor.ActorLogging  
import me.rerun.akkanotes.messaging.protocols.TeacherProtocol._  
import me.rerun.akkanotes.messaging.protocols.StudentProtocol._  
import akka.actor.Props  
import akka.actor.ActorRef

class StudentActor (teacherActorRef:ActorRef) extends Actor with ActorLogging {

  def receive = {
    case InitSignal=> {
      teacherActorRef!QuoteRequest
    }

    case QuoteResponse(quoteString) => {
      log.info ("Received QuoteResponse from Teacher")
      log.info(s"Printing from Student Actor $quoteString")
    }
  }
}

三、TeacherActor用QuoteResponse作出了响应

　　TeacherActor接收到了QuoteRequest消息，并且用QuoteResponse 作为响应

package me.rerun.akkanotes.messaging.requestresponse

import scala.util.Random

import akka.actor.Actor  
import akka.actor.ActorLogging  
import akka.actor.actorRef2Scala  
import me.rerun.akkanotes.messaging.protocols.TeacherProtocol._


class TeacherActor extends Actor with ActorLogging {

  val quotes = List(
    "Moderation is for cowards",
    "Anything worth doing is worth overdoing",
    "The trouble is you think you have time",
    "You never gonna know if you never even try")

  def receive = {

    case QuoteRequest => {

      import util.Random

      //Get a random Quote from the list and construct a response
      val quoteResponse = QuoteResponse(quotes(Random.nextInt(quotes.size)))

      //respond back to the Student who is the original sender of QuoteRequest
      sender ! quoteResponse

    }
  }
}

测试用例

现在，我们的测试用例将模拟DriverApp。然而StudentActor仅仅是把消息记录下来，它不会在QuoteResponse 进行检查。我们仅仅在EventStream 查看这些日志。我们的测试用例看起来如下：

"A student" must {

    "log a QuoteResponse eventually when an InitSignal is sent to it" in {

      import me.rerun.akkanotes.messaging.protocols.StudentProtocol._

      val teacherRef = system.actorOf(Props[TeacherActor], "teacherActor")
      val studentRef = system.actorOf(Props(new StudentActor(teacherRef)), "studentActor")

      EventFilter.info (start="Printing from Student Actor", occurrences=1).intercept{
        studentRef!InitSignal
      }
    }
  }