C# socket 包含断线重连功能的TCP客户端 具有发送失败缓存，等重连后继续发送

在C#中，为了创建一个具备断线重连和发送失败缓存功能的TCP客户端，你可以使用System.Net.Sockets命名空间下的TcpClient类，并结合Socket类的一些特性。以下是一个简单的示例：

using System;
using System.Net;
using System.IO;

public class ReconnectableClient
{
    private TcpClient client;
    private Socket socket;
    private Queue<string> sendQueue = new Queue<string>();
    private const int BufferSize = 1024;
    private bool isConnected = false;

    public void Connect(string ipAddress, int port)
    {
        while (!isConnected)
        {
            try
            {
                client = new TcpClient(ipAddress, port);
                socket = client.GetSocketAsyncStateObject();
                socket.ReceiveBufferSize = BufferSize;
                socket.SendBufferSize = BufferSize;
                socket.BeginConnect(ipAddress, port, ConnectCallback, socket);
                isConnected = true;
            }
            catch (Exception ex)
            {
                Console.WriteLine($"Connection failed: {ex.Message}. Retrying in 5 seconds...");
                Thread.Sleep(5000); // 休眠5秒再尝试连接
            }
        }
    }

    private void ConnectCallback(IAsyncResult ar)
    {
        try
        {
            socket.EndConnect(ar);
            // 开始接收数据并处理发送队列
            StartReceiving();
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Error during connection: {ex.Message}");
            CloseConnection();
        }
    }

    private void StartReceiving()
    {
        NetworkStream stream = client.GetStream();
        stream.BeginRead(new byte[BufferSize], 0, BufferSize, ReadCallback, stream);
    }

    private void ReadCallback(IAsyncResult ar)
    {
        NetworkStream stream = (NetworkStream)ar.AsyncState;
        int bytesRead = stream.EndRead(ar);

        if (bytesRead > 0)
        {
            string message = Encoding.ASCII.GetString(stream.ReadBytes(bytesRead));
            Console.WriteLine("Received: " + message);

            // 如果有未发送的数据，开始发送
            if (sendQueue.Count > 0)
            {
                SendMessage();
            }
        }
        else
        {
            // 没有接收到数据，可能是断开连接，检查并重试
            CheckAndRetrySend();
        }
    }

    private void SendMessage()
    {
        string message = sendQueue.Dequeue();
        byte[] data = Encoding.ASCII.GetBytes(message);
        socket.Send(data, 0, data.Length);
    }

    private void CheckAndRetrySend()
    {
        if (client.Connected && !socket.Connected)
        {
            Console.WriteLine("Lost connection, attempting to reconnect...");
            CloseConnection();
            Connect();
        }
        else if (sendQueue.Count > 0)
        {
            SendMessage();
        }
    }

    private void CloseConnection()
    {
        try
        {
            socket.Shutdown(SocketShutdown.Both);
            client.Close();
            isConnected = false;
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Error closing connection: {ex.Message}");
        }
    }

    // 添加到发送队列的方法
    public void EnqueueMessage(string message)
    {
        sendQueue.Enqueue(message);
    }
}

在这个示例中，`ReconnectableClient`类包含了连接、读取、发送以及重连的基本逻辑。如果发送失败，数据会被放入发送队列，待重连成功后再尝试发送。