C#中TCP异步与应用层协议的开发.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Net;
using System.Net.Sockets;
using System.Threading;

namespace TCP聊天室
...{
    public partial class Form1 : Form
    ...{
        private IPEndPoint MyServer;
        private Socket sock;
        private Thread myThread;
        private Socket[] clientsock;
        private int clientnum;
        private byte[] buffer;

        public Form1()
        ...{
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        ...{
            MyServer = new IPEndPoint(IPAddress.Any, 10000);
            sock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            sock.Bind(MyServer);
            sock.Listen(10);
            CheckForIllegalCrossThreadCalls = false;
            clientsock = new Socket[65535];
            clientnum = 0;
            buffer = new byte[65535];
            myThread = new Thread(recvaccept);
            myThread.Start();
        }

        private void recvaccept()
        ...{
            while (true)
            ...{
                clientsock[clientnum] = sock.Accept();
                clientsock[clientnum].BeginReceive(buffer, 0, buffer.Length, 0, new AsyncCallback(ReceiveCallback), clientsock[clientnum]);
                clientlist.Items.Add(clientsock[clientnum].RemoteEndPoint.ToString());
                clientnum++;
            }
        }

        private void Form1_FormClosing(object sender, FormClosingEventArgs e)
        ...{
            sock.Close();
            myThread.Abort();
        }

        private void ReceiveCallback(IAsyncResult ar)
        ...{
            try
            ...{
                Socket a = (Socket)ar.AsyncState;
                int read = a.EndReceive(ar);
                //clientlist.Items.Add(Encoding.ASCII.GetString(buffer,0,read)); 
                for (int i = 0; i < clientnum; i++)
                ...{
                    if (clientsock[i].Connected)
                    ...{
                        clientsock[i].Send(buffer, 0, read, 0);
                    }
                }
                a.BeginReceive(buffer, 0, buffer.Length, 0, new AsyncCallback(ReceiveCallback), a);
            }
            catch
            ...{ }
        }
    }
}

 

以上是一个C#聊天室服务端的原代码.代码简单粗糙,在修正了几个bug以后总算能够运行了.值得注意的地方就是BeginReceive和EndReceive这两个异步方法.在接受信息后将信息转发给所有聊天室客户端.

以及每一次连接都将新建一个socket连接.

以下是一个客户端和服务端的应用层协议.就是先发送一个4个字节的包头,包含包体字节数,来确定包是否正确接收完

private void AcceptMessage()
        ...{
            Socket socket = new Socket(AddressFamily.InterNetwork,SocketType.Stream,ProtocolType.Tcp);
            NetworkStream stream = new NetworkStream(socket);
            while (true)
            ...{
                try
                ...{
                    byte[] datasize = new byte[4];
                    stream.Read(datasize, 0, 4);
                    int size = BitConverter.ToInt32(datasize, 0);
                    byte[] message = new byte[size];
                    int dataleft = size;
                    int start = 0;
                    while (dataleft > 0)
                    ...{
                        int recv = stream.Read(message, start, dataleft);
                        start += recv;
                        dataleft -= recv;
                    }
                }
                catch ...{ }
            }
        }

 private void buttonSend_Click(object sender, System.EventArgs e)
 ...{
            string str = this.richTextBoxSend.Rtf;
            int i = str.Length;
            if (i == 0)
            ...{
                return;
            }
            else
            ...{
                i *= 2;
            }
        byte[] datasize = new byte[4];
        datasize = BitConverter.GetBytes(i);
        byte[] sendbytes=Encoding.Unicode.GetBytes(str);
        try
        ...{
           NetworkStream netStream=new NetworkStream(clientSocket);
           netStream.Wirte(datasize,0,4);
           netStream.Write(sendbytes,0,sendbytes.Length);
           netStream.Flush();
           this.richTextBoxSend.Rtf="";
        }
        catch...{}
 }