.Net TCP探索（一）——TCP服务端开发(同时监听多个客户端请求)

    最近在园子里看了大神写的（面试官，不要再问我三次握手和四次挥手），忍不住写段程序来测试一番。

    在网上找了很多例子，大多只实现了TCP点对点通讯，但实际应用中，一个服务器端口往往要监听多个客户端发来的消息。

测试工具下载：https://download.csdn.net/download/nbyanghuichao/11872360
    本例采用System.Threading实现多线程监听，下面只介绍核心代码，省略了消息提示和错误处理，可以从我的GitHub获取完整代码：https://github.com/FB208/CodeSpace/tree/master/CodeSpace.CSharp/TCP.Client

数据声明：

private string _ip;//IP
private int _port;//端口
//客户端集合
public static List<TcpClientModel> clients = new List<TcpClientModel>
private static byte[] bytes = new byte[1024 * 100];
/// <summary>
/// 用于存储客户端
/// </summary>
public class TcpClientModel
{
    /// <summary>
    /// IP:Port
    /// </summary>
    public string RemoteEndPoint { get; set; }
    /// <summary>
    /// 客户端链接对象
    /// </summary>
    public TcpClient TcpClient { get; set; }
}

启动监听：

///启动监听
void Init()
{
    try
    {
        IPAddress ip = IPAddress.Parse(_ip);
        int port = _port;
        TcpListener listener = new TcpListener(ip, port);
        //启动监听
        listener.Start();
        tb_console.AppendText($"Listener...\r\n");
        //异步接收 递归循环接收多个客户端
        listener.BeginAcceptTcpClient(new AsyncCallback(GetAcceptTcpclient), listener);
    }
    catch (Exception ex)
    {
        
    }
}

接收客户端：

private void GetAcceptTcpclient(IAsyncResult State)
{
    //处理多个客户端接入
    TcpListener listener = (TcpListener)State.AsyncState;
    //接收到客户端请求
    TcpClient client = listener.EndAcceptTcpClient(State);
    //保存到客户端集合中
    clients.Add(new TcpClientModel() { TcpClient = client, RemoteEndPoint = client.Client.RemoteEndPoint.ToString() });

    //开启线程用来持续接收来自客户端的数据
    Thread myThread = new Thread(() =>
    {
        ReceiveMsgFromClient(client);
    });
    myThread.Start();
    listener.BeginAcceptTcpClient(new AsyncCallback(GetAcceptTcpclient), listener);
}

接收消息并响应客户端：

private void ReceiveMsgFromClient(object reciveClient)
{
    TcpClient client = reciveClient as TcpClient;
    if (client == null)
    {
        return;
    }
    while (true)
    {
        try
        {
            NetworkStream stream = client.GetStream();
            int num = stream.Read(bytes, 0, bytes.Length); //将数据读到result中，并返回字符长度                  
            if (num != 0)
            {
                //把字节数组中流存储的数据以字符串方式赋值给str
                //这里就是接收到的客户端消息
                string str = Encoding.UTF8.GetString(bytes, 0, num);

                //给客户端返回一个消息
                string msg = "Your message has been received by the server[" + str + "]";

                bool result = TCPHelper.SendToClient(client, msg, out msg);
                if (!result)
                {
                    //发送失败
                }
            }
            else
            {   
                //这里需要注意 当num=0时表明客户端已经断开连接，需要结束循环，不然会死循环一直卡住
                break;
            }
        }
        catch (Exception ex)
        {
            //链接失败 从集合中移除出错客户端
            clients.Remove(clients.FirstOrDefault(m => m.RemoteEndPoint == client.Client.RemoteEndPoint.ToString()));
            break;
        }

    }
}

从服务器向客户端发送消息的工具类：

public static class TCPHelper
{
    public static bool SendToClient(TcpClient client, string message,out string errorMsg)
    {
        try
        {
            byte[] bytes = new byte[1024 * 100];
            bytes = Encoding.UTF8.GetBytes(message);
            NetworkStream stream = client.GetStream();
            stream.Write(bytes, 0, bytes.Length);
            stream.Flush();
            errorMsg = "";
            return true;
        }
        catch (Exception ex)
        {
            errorMsg = ex.Message;
            return false;
        }
    }
}

测试效果：

完整代码请关注：https://github.com/FB208/CodeSpace/tree/master/CodeSpace.CSharp/TCP.Client