C# 实现基于 TCP 的简单聊天程序（服务端）

使用 TcpListener 实现 TCP 服务端，监听客户端连接并转发消息。
using System.Net;
using System.Net.Sockets;
using System.Text;

public class TcpChatServer
{
private TcpListener _listener;
private List _clients = new List();
private readonly object _lockObj = new object();

public async Task Start(int port)
{
    _listener = new TcpListener(IPAddress.Any, port);
    _listener.Start();
    Console.WriteLine("服务器已启动，监听端口: " + port);

    while (true)
    {
        var client = await _listener.AcceptTcpClientAsync();
        lock (_lockObj) _clients.Add(client);
        Console.WriteLine("新客户端连接");
        _ = HandleClient(client);
    }
}

private async Task HandleClient(TcpClient client)
{
    NetworkStream stream = client.GetStream();
    byte[] buffer = new byte[1024];

    try
    {
        while (client.Connected)
        {
            int bytesRead = await stream.ReadAsync(buffer, 0, buffer.Length);
            if (bytesRead == 0) break;

            string message = Encoding.UTF8.GetString(buffer, 0, bytesRead);
            Console.WriteLine($"客户端: {message}");
            // 广播消息给所有客户端
            await BroadcastMessage(message, client);
        }
    }
    catch (Exception ex)
    {
        Console.WriteLine($"客户端处理异常: {ex.Message}");
    }
    finally
    {
        lock (_lockObj) _clients.Remove(client);
        client.Close();
    }
}

private async Task BroadcastMessage(string message, TcpClient sender)
{
    byte[] data = Encoding.UTF8.GetBytes(message);
    lock (_lockObj)
    {
        foreach (var client in _clients)
        {
            if (client != sender && client.Connected)
            {
                await client.GetStream().WriteAsync(data, 0, data.Length);
            }
        }
    }
}

// 调用示例
public static async Task TestServer()
{
    var server = new TcpChatServer();
    await server.Start(8888);
}

}