Kotlin Socket客户端连接localhost:9999被拒，求解决方案

问题概述 #

我正在学习一段Kotlin Socket代码，目标连接本地地址http://127.0.0.1，已在本地启用并运行IIS，但代码执行时抛出java.io.IOException: The remote computer refused the network connection错误；同时访问错误格式的地址localhost/127.0.0.1:9999时返回404，代码中实际使用InetSocketAddress("localhost", PORT)（PORT值为9999）建立连接。

代码执行错误日志 #

"C:\Program Files\Microsoft\jdk-11.0.12.7-hotspot\bin\java.exe" -agentlib:jdwp=transport=dt_socket,address=127.0.0.1:52769,suspend=y,server=n -javaagent:C:/Users/ivlat/.gradle/caches/modules-2/files-2.1/org.jetbrains.kotlinx/kotlinx-coroutines-core-jvm/1.5.0/d8cebccdcddd029022aa8646a5a953ff88b13ac8/kotlinx-coroutines-core-jvm-1.5.0.jar -javaagent:C:\Users\ivlat\AppData\Local\JetBrains\IdeaIC2022.2\captureAgent\debugger-agent.jar=file:/C:/Users/ivlat/AppData/Local/Temp/capture.props -Dfile.encoding=UTF-8 -classpath "C:\Dev\KotlinProjects\7_08_Echo\client\build\classes\kotlin\main;C:\Users\ivlat\.gradle\caches\modules-2\files-2.1\org.jetbrains.kotlin\kotlin-stdlib-jdk8\1.5.21\6b3de2a43405a65502728047db37a98a0c7e72f0\kotlin-stdlib-jdk8-1.5.21.jar;C:\Users\ivlat\.gradle\caches\modules-2\files-2.1\ch.qos.logback\logback-classic\1.2.3\7c4f3c474fb2c041d8028740440937705ebb473a\logback-classic-1.2.3.jar;C:\Users\ivlat\.gradle\caches\modules-2\files-2.1\ch.qos.logback\logback-core\1.2.3\864344400c3d4d92dfeb0a305dc87d953677c03c\logback-core-1.2.3.jar;C:\Dev\KotlinProjects\7_08_Echo\shared\build\classes\kotlin\main;C:\Users\ivlat\.gradle\caches\modules-2\files-2.1\org.jetbrains.kotlinx\kotlinx-coroutines-core-jvm\1.5.0\d8cebccdcddd029022aa8646a5a953ff88b13ac8\kotlinx-coroutines-core-jvm-1.5.0.jar;C:\Users\ivlat\.gradle\caches\modules-2\files-2.1\org.jetbrains.kotlin\kotlin-stdlib-jdk7\1.5.21\f059658740a4b3a3461aba9681457615332bae1c\kotlin-stdlib-jdk7-1.5.21.jar;C:\Users\ivlat\.gradle\caches\modules-2\files-2.1\org.jetbrains.kotlin\kotlin-stdlib\1.5.21\2f537cad7e9eeb9da73738c8812e1e4cf9b62e4e\kotlin-stdlib-1.5.21.jar;C:\Users\ivlat\.gradle\caches\modules-2\files-2.1\org.slf4j\slf4j-api\1.7.25\da76ca59f6a57ee3102f8f9bd9cee742973efa8a\slf4j-api-1.7.25.jar;C:\Users\ivlat\.gradle\caches\modules-2\files-2.1\org.jetbrains.kotlin\kotlin-stdlib-common\1.5.21\cc8bf3586fd2ebcf234058b9440bb406e62dfacb\kotlin-stdlib-common-1.5.21.jar;C:\Users\ivlat\.gradle\caches\modules-2\files-2.1\org.jetbrains\annotations\13.0\919f0dfe192fb4e063e7dacadee7f8bb9a2672a9\annotations-13.0.jar;C:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2022.2.3\lib\idea_rt.jar" com.knowledgespike.client.ApplicationKt
Connected to the target VM, address: '127.0.0.1:52769', transport: 'socket'
Exception in thread "main" java.io.IOException: The remote computer refused the network connection.

    at java.base/sun.nio.ch.Iocp.translateErrorToIOException(Iocp.java:299)
    at java.base/sun.nio.ch.Iocp$EventHandlerTask.run(Iocp.java:389)
    at java.base/sun.nio.ch.AsynchronousChannelGroupImpl$1.run(AsynchronousChannelGroupImpl.java:112)
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
    at java.base/java.lang.Thread.run(Thread.java:829)
Disconnected from the target VM, address: '127.0.0.1:52769', transport: 'socket'

Process finished with exit code 1

网页访问错误 #

HTTP Error 404.0 - Not Found
The resource you are looking for has been removed, had its name changed, or is temporarily unavailable.

相关Kotlin代码 #

fun main() = runBlocking {

    val client: AsynchronousSocketChannel = AsynchronousSocketChannel.open()
    val hostAddress = InetSocketAddress("localhost", PORT)
    val tcpSocket = TcpSocket(client)
    tcpSocket.connect(hostAddress)

    val br = BufferedReader(InputStreamReader(System.`in`))
    var line: String
    println("Main name is: 					${Thread.currentThread().name}")
    println("Message to server:")
    while (br.readLine().also { line = it } != null) {
        val result = async {
            println("while:async name is: 			${Thread.currentThread().name}")
            sendMessage(tcpSocket, line)
        }
        println("while: name is: 				${Thread.currentThread().name}")
        if (line == "bye") {
            println("End")
            break
        }
        val response: String = result.await()
        withContext(Dispatchers.Default) {
            println("withContext[Default] name is: 	${Thread.currentThread().name}")
            println("response from server: $response")
            println("Message to server:")
        }
    }
}

解决方案 #

一、IIS配置步骤 #

1. 修正端口绑定

   • 打开IIS管理器，找到目标网站，右键选择「编辑绑定」
   • 添加或修改绑定：类型选「HTTP」，IP地址选择「127.0.0.1」或「所有未分配」，端口设置为9999，主机名留空
   • 保存设置后，执行命令iisreset重启IIS服务

2. 检查防火墙规则

   • 打开Windows Defender防火墙，进入「高级设置」
   • 添加入站规则，允许TCP协议在9999端口接收连接

3. 修正访问地址格式

   • 访问时使用正确格式：http://localhost:9999或http://127.0.0.1:9999，而非错误的localhost/127.0.0.1:9999

二、推荐调试用测试服务器 #

• Ktor（Kotlin专属）：用Ktor框架可以快速搭建Echo服务，几行代码就能监听9999端口并响应Socket请求，完全适配Kotlin开发环境
• Python内置服务器：命令行执行python -m http.server 9999，快速启动静态文件服务器，适合基础连接测试
• Node.js http-server：安装后执行http-server -p 9999，轻量级HTTP服务器，启动和关闭都很便捷

内容的提问来源于stack exchange，提问作者Ivan