Unity与TypeScript WebSocket通信时出现字符串转换错误

问题背景 #

用TypeScript搭建WebSocket服务器对接Unity客户端时，出现字符串转换错误。朋友使用我的服务器代码在Unity中运行无异常，但我将自己的客户端代码放到其他项目中仍会触发相同错误。系统语言为韩语，但项目目录内未发现韩语内容。

Unity客户端C#代码 #

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using System.Net.WebSockets;
using System;
using System.Threading;

public class SocketManager : MonoBehaviour
{
    private ClientWebSocket _socket = null;

    private void Start()
    {
        Connection();
    }

    public async void Connection()
    {
        Debug.Log("Starting Connection");
        if (_socket != null && _socket.State == WebSocketState.Open)
        {
            Debug.Log("Socket already connected");
            return;
        }

        _socket = new ClientWebSocket();
        Uri serverUri = new Uri("ws://localhost:50000");

        await _socket.ConnectAsync(serverUri, CancellationToken.None);

        Debug.Log("Connected");

        ArraySegment<byte> bufferSegment = new ArraySegment<byte>(new byte[1024]);
        WebSocketReceiveResult result = await _socket.ReceiveAsync(bufferSegment, CancellationToken.None);

        string msg = System.Text.Encoding.UTF8.GetString(bufferSegment.Array);
        Debug.Log(msg);
    }

    private void OnDestroy()
    {
        Disconnect();
    }

    public void Disconnect()
    {
        if (_socket != null)
        {
            _socket.CloseAsync(WebSocketCloseStatus.NormalClosure,
                               "Quit",
                               CancellationToken.None);
        }
    }
}

TypeScript WebSocket服务器代码 #

import Express, { Application } from 'express';
import {IncomingMessage} from 'http'
import WS from 'ws';

const App: Application = Express();

const httpServer = App.listen(50000, ()=>{
    console.log("Server is running on 50000 port");
});

const socketServer : WS.Server = new WS.Server({
    server:httpServer,
    //port:9090
}, () => {
    console.log("Socket server is running on 50000 port");
});

socketServer.on("connection", (soc:WS, req:IncomingMessage) => {
    payload: Uint8Array = new Uint8Array(20);
    soc.send("Welcome to My Server!");
});

错误信息 #

ExecutionEngineException: String conversion error: Illegal byte sequence encounted in the input.
System.Net.Dns.GetHostByName (System.String hostName) (at :0)
System.Net.Dns.GetHostEntry (System.String hostNameOrAddress) (at :0)
System.Net.Dns.GetHostAddresses (System.String hostNameOrAddress) (at :0)
(wrapper delegate-end-invoke) .end_invoke_IPAddress[]__this___IAsyncResult(System.IAsyncResult)
System.Net.Dns.EndGetHostAddresses (System.IAsyncResult asyncResult) (at :0)
System.Threading.Tasks.TaskFactory1[TResult].FromAsyncCoreLogic (System.IAsyncResult iar, System.Func2[T,TResult] endFunction, System.Action1[T] endAction, System.Threading.Tasks.Task1[TResult] promise, System.Boolean requiresSynchronization) (at :0)
End of stack trace from previous location where exception was thrown ---

排查与解决方法 #

1. 绕开DNS解析 #

错误栈显示问题出在DNS解析阶段，和韩语系统的编码设置冲突。直接使用IP地址替代localhost：

Uri serverUri = new Uri("ws://127.0.0.1:50000");

同时检查系统hosts文件，确保localhost指向127.0.0.1，且文件内无韩语或非ASCII字符。

2. 修正字符串解码逻辑 #

当前解码时使用整个buffer数组，包含未使用的空字节，易引发编码错误。仅解码实际接收的字节长度：

string msg = System.Text.Encoding.UTF8.GetString(bufferSegment.Array, 0, result.Count);

3. 修复服务器代码语法错误 #

服务器代码存在未声明变量的语法问题，虽未实际使用，但可能影响稳定性：

// 原错误代码
// payload: Uint8Array = new Uint8Array(20);
// 修正后
const payload: Uint8Array = new Uint8Array(20);

4. 调整Unity与系统编码设置 #

• 在Unity中打开Edit > Project Settings > Player，将Other Settings里的Scripting Runtime Version设为.NET 4.x Equivalent，提升编码兼容性。
• 调整系统区域语言设置，将非Unicode程序的语言设为英语（美国），避免编码转换冲突。

内容的提问来源于stack exchange，提问作者Minjoon Park