Ktor CIO wss 套接字立即关闭答案

【问题标题】：Ktor CIO wss socket closes immediatelyKtor CIO wss 套接字立即关闭
【发布时间】：2019-03-08 11:22:46
【问题描述】：

使用 ktor CIO ws 时，它按预期工作，但使用 wss 时，它会立即关闭。任何帮助是极大的赞赏。卡了一天了。

这是我为 wss 获取的堆栈跟踪

kotlinx.coroutines.experimental.channels.ClosedReceiveChannelException: Channel was closed
    at kotlinx.coroutines.experimental.channels.Closed.getReceiveException(AbstractChannel.kt:1067)
    at kotlinx.coroutines.experimental.channels.AbstractChannel$ReceiveElement.resumeReceiveClosed(AbstractChannel.kt:907)
    at kotlinx.coroutines.experimental.channels.AbstractSendChannel.helpClose(AbstractChannel.kt:317)
    at kotlinx.coroutines.experimental.channels.AbstractSendChannel.close(AbstractChannel.kt:254)
    at kotlinx.coroutines.experimental.channels.ChannelCoroutine.close(ChannelCoroutine.kt)
    at kotlinx.coroutines.experimental.channels.SendChannel$DefaultImpls.close$default(Channel.kt:84)
    at io.ktor.network.tls.TLSClientHandshake$input$1.doResume(TLSClientHandshake.kt:96)
    at kotlin.coroutines.experimental.jvm.internal.CoroutineImpl.resumeWithException(CoroutineImpl.kt:48)
    at kotlin.coroutines.experimental.jvm.internal.CoroutineImpl.resumeWithException(CoroutineImpl.kt:47)
    at kotlin.coroutines.experimental.jvm.internal.CoroutineImpl.resume(CoroutineImpl.kt:41)
    at kotlinx.coroutines.experimental.DispatchedTask$DefaultImpls.run(Dispatched.kt:149)
    at kotlinx.coroutines.experimental.io.internal.MutableDelegateContinuation.run(MutableDelegateContinuation.kt:14)
    at io.ktor.network.util.IOCoroutineDispatcher$IODispatchedTask.run(IOCoroutineDispatcher.kt)
    at io.ktor.network.util.IOCoroutineDispatcher$IOThread$run$1.doResume(IOCoroutineDispatcher.kt:73)
    at kotlin.coroutines.experimental.jvm.internal.CoroutineImpl.resume(CoroutineImpl.kt:42)
    at kotlinx.coroutines.experimental.DispatchedTask$DefaultImpls.run(Dispatched.kt:149)
    at kotlinx.coroutines.experimental.DispatchedContinuation.run(Dispatched.kt:13)
    at kotlinx.coroutines.experimental.EventLoopBase.processNextEvent(EventLoop.kt:140)
    at kotlinx.coroutines.experimental.BlockingCoroutine.joinBlocking(Builders.kt:70)
    at kotlinx.coroutines.experimental.BuildersKt__BuildersKt.runBlocking(Builders.kt:46)
    at kotlinx.coroutines.experimental.BuildersKt.runBlocking(Unknown Source)
    at io.ktor.network.util.IOCoroutineDispatcher$IOThread.run(IOCoroutineDispatcher.kt:68)

代码如下：

httpClient.ws(host = "echo.websocket.org") {
  send(Frame.Text("Hello World"))

  for (message in incoming.map { it as? Frame.Text }.filterNotNull()) {
    println(message.readText())
  }
}

httpClient.wss(host = "echo.websocket.org") {
  send(Frame.Text("Hello World"))

  for (message in incoming.map { it as? Frame.Text }.filterNotNull()) {
    println(message.readText())
  }
}

【问题讨论】：

标签： websocket kotlin ktor

【解决方案1】：

我有一个安全 WebSockets 的问题，它已在 ktor 1.3.2 中修复。

我还想提一下echo.websocket.org 不会关闭连接，所以 for 循环将永远暂停（期待下一个 pong 消息）。

为了避免这种情况你可以重写

for (message in incoming.map { it as? Frame.Text }.filterNotNull()) {
    println(message.readText())
}

作为

val pong = incoming.receive() as Frame.Text
println(pong.readText())

在发送第一条消息后显式调用close() 也应该没问题，但目前不支持。我为此提交了单独的问题：https://github.com/ktorio/ktor/issues/1946

【讨论】：