這是我相信你在找的一個簡單的例子。它顯示了像演員這樣的主人如何產生一些童工,然後等待他們的所有反應,處理可能發生超時等待結果的情況。該解決方案顯示瞭如何等待初始請求,然後在等待響應時切換到新的接收函數。它還展示瞭如何將狀態傳播到等待接收函數中,以避免在實例級別具有顯式的可變狀態。
object TaxCalculator {
sealed trait TaxType
case object StateTax extends TaxType
case object FederalTax extends TaxType
case object PoliceDistrictTax extends TaxType
val AllTaxTypes:Set[TaxType] = Set(StateTax, FederalTax, PoliceDistrictTax)
case class GetTaxAmount(grossEarnings:Double)
case class TaxResult(taxType:TaxType, amount:Double)
case class TotalTaxResult(taxAmount:Double)
case object TaxCalculationTimeout
}
class TaxCalculator extends Actor{
import TaxCalculator._
import context._
import concurrent.duration._
def receive = waitingForRequest
def waitingForRequest:Receive = {
case gta:GetTaxAmount =>
val children = AllTaxTypes map (tt => actorOf(propsFor(tt)))
children foreach (_ ! gta)
setReceiveTimeout(2 seconds)
become(waitingForResponses(sender, AllTaxTypes))
}
def waitingForResponses(respondTo:ActorRef, expectedTypes:Set[TaxType], taxes:Map[TaxType, Double] = Map.empty):Receive = {
case TaxResult(tt, amount) =>
val newTaxes = taxes ++ Map(tt -> amount)
if (newTaxes.keySet == expectedTypes){
respondTo ! TotalTaxResult(newTaxes.values.foldLeft(0.0)(_+_))
context stop self
}
else{
become(waitingForResponses(respondTo, expectedTypes, newTaxes))
}
case ReceiveTimeout =>
respondTo ! TaxCalculationTimeout
context stop self
}
def propsFor(taxType:TaxType) = taxType match{
case StateTax => Props[StateTaxCalculator]
case FederalTax => Props[FederalTaxCalculator]
case PoliceDistrictTax => Props[PoliceDistrictTaxCalculator]
}
}
trait TaxCalculatingActor extends Actor{
import TaxCalculator._
val taxType:TaxType
val percentage:Double
def receive = {
case GetTaxAmount(earnings) =>
val tax = earnings * percentage
sender ! TaxResult(taxType, tax)
}
}
class FederalTaxCalculator extends TaxCalculatingActor{
val taxType = TaxCalculator.FederalTax
val percentage = 0.20
}
class StateTaxCalculator extends TaxCalculatingActor{
val taxType = TaxCalculator.StateTax
val percentage = 0.10
}
class PoliceDistrictTaxCalculator extends TaxCalculatingActor{
val taxType = TaxCalculator.PoliceDistrictTax
val percentage = 0.05
}
然後,你可以用下面的代碼測試了這一點:
import TaxCalculator._
import akka.pattern.ask
import concurrent.duration._
implicit val timeout = Timeout(5 seconds)
val system = ActorSystem("taxes")
import system._
val cal = system.actorOf(Props[TaxCalculator])
val fut = cal ? GetTaxAmount(1000.00)
fut onComplete{
case util.Success(TotalTaxResult(amount)) =>
println(s"Got tax total of $amount")
case util.Success(TaxCalculationTimeout) =>
println("Got timeout calculating tax")
case util.Failure(ex) =>
println(s"Got exception calculating tax: ${ex.getMessage}")
}
考慮將稅收管理機構作爲對象而不是演員,並將行項目的納稅責任計算爲未來,如http://danielwestheide.com/blog/2013/01/09/the-新手指南-scala-part-8-welcome-to-the-future.html –
您是否需要爲每個訂單項使用Actor? [Akka docs](http://doc.akka.io/docs/akka/2.3.1/scala/futures.html#Use_Directly)建議爲這種情況評估「未來」。 – tariksbl