C#编写一个带有回调的异步TCP客户端

下面是一个简单的C#异步TCP客户端，带有回调函数来处理数据：

using System;
using System.Net;
using System.Net.Sockets;
using System.Text;

public class AsyncTcpClient
{
    private TcpClient _client;
    private byte[] _buffer = new byte[1024];

    public void Connect(string host, int port, Action<string> callback)
    {
        _client = new TcpClient();
        _client.BeginConnect(host, port, ar =>
        {
            _client.EndConnect(ar);
            callback("Connected to " + host + ":" + port);
            StartReading();
        }, null);
    }

    public void Send(string message)
    {
        byte[] data = Encoding.UTF8.GetBytes(message);
        _client.GetStream().BeginWrite(data, 0, data.Length, ar =>
        {
            _client.GetStream().EndWrite(ar);
        }, null);
    }

    private void StartReading()
    {
        _client.GetStream().BeginRead(_buffer, 0, _buffer.Length, ar =>
        {
            int bytesRead = _client.GetStream().EndRead(ar);
            string message = Encoding.UTF8.GetString(_buffer, 0, bytesRead);
            OnMessageReceived(message);
            StartReading();
        }, null);
    }

    private void OnMessageReceived(string message)
    {
        Console.WriteLine("Received message: " + message);
    }

    public void Disconnect()
    {
        _client.Close();
    }
}

使用示例：

var client = new AsyncTcpClient();
client.Connect("127.0.0.1", 8888, message =>
{
    Console.WriteLine(message);
});

client.Send("Hello, server!");

Console.ReadLine();

client.Disconnect();

在这个例子中，我们创建了一个异步TCP客户端，它连接到指定的主机和端口。当连接成功时，回调函数被调用并显示连接消息。我们还可以使用`Send`方法向服务器发送消息。当我们收到来自服务器的消息时，回调函数`OnMessageReceived`被调用。最后，我们使用`Disconnect`方法关闭连接。