在spark-shell中输入范例中的代码:
import akka.actor.Actor
import akka.actor.Props
import akka.event.Logging
class MyActor extends Actor {
val log = Logging(context.system, this)
def receive = {
case "test" ⇒ log.info("received test")
case _ ⇒ log.info("received unknown message")
}
}
val system = ActorSystem("MySystem")
val myActor = system.actorOf(Props[MyActor], name = "myactor")
结果总是遇到如下错误:
scala> val myActor = system.actorOf(Props[MyActor], name = "myactor")
java.lang.IllegalArgumentException: no matching constructor found on class $iwC$$iwC$$iwC$$iwC$MyActor for arguments []
at akka.util.Reflect$.error$1(Reflect.scala:81)
at akka.util.Reflect$.findConstructor(Reflect.scala:93)
at akka.actor.Props.constructor(Props.scala:194)
at akka.actor.Props.(Props.scala:213)
at akka.actor.Props$.apply(Props.scala:69)
at $iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC.(:24)
百思不得其解!最后终于找到了原因:不能采用内嵌类作为actor类!!!!spark-shell里面的类会被认为是内嵌类,为了避免以上错误,需要单独写类文件。
stackoverflow里面是这么解释的:
Take this example:
class A{
class B{}
}
I can do new A
, but new B
will return an error. I have to do:
val a = new A
val b = new a.B
That's why akka failed to create this actor.