在Akka的WebSocket处理程序中出现'无法订阅关闭Publisher”错误,这通常是因为在处理WebSocket事件时,Akka已经停止了Actor系统,但在回调WebSocket应用程序时,Actor系统仍在后台运行。因此,解决方案是使用Akka的 'onPreStart'钩子方法来监听Actor系统的终止,并在WebSocket应用程序的回调中避免 'Publisher'的使用。以下是示例代码:
import akka.actor.Actor
import akka.stream.scaladsl.{Flow, Source}
import akka.http.scaladsl.model.ws.{Message, TextMessage, WebSocketRequest}
import akka.stream.ActorMaterializer
class WebSocketActor extends Actor {
implicit val materializer = ActorMaterializer()
def receive = {
case message: TextMessage =>
val source = Source.single(TextMessage("Hello, World!"))
val flow = Flow.fromSinkAndSourceMat(printSink, source)(Keep.right)
sender() ! flow
case _ =>
sender() ! "Invalid message"
}
override def preStart() = {
context.system.whenTerminated.foreach(_ => materializer.shutdown())
}
def printSink = Sink.foreach[Message] {
case tm: TextMessage => println(tm.getStrictText)
case _ => println("Unkown Message")
}
}
在上面的代码示例中,使用Akka的 'whenTerminated'方法监听 'Actor'系统的终止,并在回调WebSocket应用程序时避免了 'Publisher'的使用。