Question

我正在按照webSocketClientFlow上的文档尝试客户端websocket。

示例代码是：

import akka.actor.ActorSystem
import akka.Done
import akka.http.scaladsl.Http
import akka.stream.ActorMaterializer
import akka.stream.scaladsl._
import akka.http.scaladsl.model._
import akka.http.scaladsl.model.ws._

import scala.concurrent.Future

object WebSocketClientFlow {
  def main(args: Array[String]) = {
    implicit val system = ActorSystem()
    implicit val materializer = ActorMaterializer()
    import system.dispatcher

    // Future[Done] is the materialized value of Sink.foreach,
    // emitted when the stream completes
    val incoming: Sink[Message, Future[Done]] =
      Sink.foreach[Message] {
        case message: TextMessage.Strict =>
          println(message.text)
      }

    // send this as a message over the WebSocket
    val outgoing = Source.single(TextMessage("hello world!"))

    // flow to use (note: not re-usable!)
    val webSocketFlow = Http().webSocketClientFlow(WebSocketRequest("ws://echo.websocket.org"))

    // the materialized value is a tuple with
    // upgradeResponse is a Future[WebSocketUpgradeResponse] that
    // completes or fails when the connection succeeds or fails
    // and closed is a Future[Done] with the stream completion from the incoming sink
    val (upgradeResponse, closed) =
      outgoing
        .viaMat(webSocketFlow)(Keep.right) // keep the materialized Future[WebSocketUpgradeResponse]
        .toMat(incoming)(Keep.both) // also keep the Future[Done]
        .run()

    // just like a regular http request we can access response status which is available via upgrade.response.status
    // status code 101 (Switching Protocols) indicates that server support WebSockets
    val connected = upgradeResponse.flatMap { upgrade =>
      if (upgrade.response.status == StatusCodes.SwitchingProtocols) {
        Future.successful(Done)
      } else {
        throw new RuntimeException(s"Connection failed: ${upgrade.response.status}")
      }
    }

    // in a real application you would not side effect here
    connected.onComplete(println)
    closed.foreach(_ => println("closed"))
  }
}

连接升级后，如何使用connection发送消息到websocket服务器端？

我从文档中注意到：

此方法返回的Flow只能实现一次。对于每个请求，必须通过再次调用该方法来获取新流。

仍然很困惑，为什么我们需要多次构建流程，因为升级后的连接准备好了。

Answer 1

您可以创建基于actor的源，并通过已建立的websocket连接发送新消息。

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如何使用Akka-HTTP客户端websocket发送消息

1 个答案: