[C#] Socket Programming

socket programming 的重點大概有幾個：

1. 有 server & client 兩端
   
2. server 只有一個，而 client 有可能會多個
   
3. server 可設定監聽(listen)的 port number

以下直接用範例來說明囉!

(其中 SocketServer 跟新的 client 連線後，會交給 ClientRequestHandler 處理)

SocketServer.cs

using System;
using System.Collections.Generic;
using System.Text;

using System.Net.Sockets;
using System.Net;
using System.ComponentModel;

namespace SocketConn
{
    class SocketServer
    {
        #region private property

        /// 
        /// socket server TCP port number
        /// 
        private int _PortNumber;


        /// 
        /// TCP Listener
        /// 
        private TcpListener _Listener;


        /// 
        /// 用來處理 Listener 工作的執行緒
        /// 
        private BackgroundWorker _bgwServer = new BackgroundWorker();


        /// 
        /// socker client 識別編號
        /// 
        private int _ClientNo = 0;

        #endregion


        #region static public property

        /// 
        /// 工作進行中產生之訊息
        /// 
        public static List sMessages = new List();

        #endregion


        #region constructor

        /// 
        /// constructor
        /// 
        /// 
socket server TCP port number
        public SocketServer(int inPortNumber)
        {
            this._PortNumber = inPortNumber;

            //委派事件
            _bgwServer.DoWork += new DoWorkEventHandler(_bgwServer_DoWork);
        }

        #endregion


        #region public method

        /// 
        /// 開始監聽
        /// 
        public void Start()
        {
            if (!_bgwServer.IsBusy)
                _bgwServer.RunWorkerAsync();
        }

        #endregion


        #region BackgroundWorker

        /// 

        /// 處理 Listener 工作
        /// 
        /// 

        /// 

        private void _bgwServer_DoWork(object sender, DoWorkEventArgs e)
        {
            try
            {
                //若 TCP Listner 正在工作，則停止
                if (_Listener != null)
                    _Listener.Stop();

                //初始化 TCPListener
                _Listener = new TcpListener(IPAddress.Any, _PortNumber);

                //啟動 listener
                _Listener.Start();
                sMessages.Add(" >> " + "Server Started");

                //========== 持續接受監聽 socket client 的連線 ========== (start)
                while (true)
                {
                    //監聽到來自 socket client 的連線要求
                    TcpClient socket4Client = _Listener.AcceptTcpClient();

                    //累加 socket client 識別編號
                    _ClientNo++;
                    sMessages.Add(" >> " + "Client Request No:" + Convert.ToString(_ClientNo) + " started!");

                    //產生 BackgroundWorker 負責處理每一個 Socket Client 的要求
                    ClientRequestHandler handler = new ClientRequestHandler(_ClientNo, socket4Client);
                    handler.DoCommunicate();
                }
                //========== 持續接受監聽 socket client 的連線 ========== (end)
            }
            catch (Exception exp)
            {
                sMessages.Add(exp.ToString());
            }
        }

        #endregion
    }
}

ClientRequestHandler.cs

using System;
using System.Collections.Generic;
using System.Text;

using System.Net.Sockets;
using System.ComponentModel;

namespace SocketConn
{
    class ClientRequestHandler
    {
        #region private property

        /// 
        /// socket client 識別號碼
        /// 
        private int _ClientNo;


        /// 
        /// socket client reuqest
        /// 
        private TcpClient _TcpClient;

        #endregion


        #region constructor

        /// 
        /// constructor
        /// 
        /// 
socket client 識別號碼
        /// 
socket client reuqest
        public ClientRequestHandler(int inClientNo, TcpClient inTcpClient)
        {
            this._ClientNo = inClientNo;
            this._TcpClient = inTcpClient;
        }

        #endregion


        #region public method

        /// 
        /// server & client 間相互進行通訊
        /// 
        public void DoCommunicate()
        {
            //產生 BackgroundWorker 負責處理每一個 socket client 的 reuqest
            BackgroundWorker bgwSocket = new BackgroundWorker();
            bgwSocket.DoWork += new DoWorkEventHandler(bgwSocket_DoWork);
            bgwSocket.RunWorkerAsync();
        }

        #endregion


        #region BackgroundWorker

        /// 
        /// 處理 socket client request
        /// 
        private void bgwSocket_DoWork(object sender, DoWorkEventArgs e)
        {
            //server & client 已經連線完成
            while (_TcpClient.Connected)
            {
                //取得網路串流物件，取得來自 socket client 的訊息
                NetworkStream netStream = _TcpClient.GetStream();
                byte[] readBuffer = new byte[1024];
                int count = 0;
                if ((count = netStream.Read(readBuffer, 0, readBuffer.Length)) != 0)
                {
                    string clientRequest = Encoding.UTF8.GetString(readBuffer, 0, count);
                    SocketServer.sMessages.Add(" >> " + "From client(" + _ClientNo + ") =>" + clientRequest);

                    //正確取得 client requst，再回傳給 client
                    string serverResponse = "Server to clinet(" + _ClientNo + ") => message: " + clientRequest;
                    byte[] sendBytes = Encoding.UTF8.GetBytes(serverResponse);
                    netStream.Write(sendBytes, 0, sendBytes.Length);
                    netStream.Flush();
                    SocketServer.sMessages.Add(" >> " + serverResponse);
                }
            }
        }

        #endregion
    }
}

SocketClient.cs

using System;
using System.Collections.Generic;
using System.Text;

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

namespace SocketConn
{
    class SocketClient
    {
        #region private property

        /// 
        /// 遠端 socket server IP 位址
        /// 
        private string _RemoteIpAddress;

        /// 
        /// 遠端 socket server 所監聽的 port number
        /// 
        private int _RemotePortNumber;


        /// 
        /// socket client 物件(連接遠端 socket server 用)
        /// 
        private TcpClient _TcpClient;

        #endregion


        #region public static property

        public static List sMessages = new List();

        #endregion


        #region constructor

        /// 
        /// constructor
        ///
        /// 
遠端 socket server IP 位址
        /// 
遠端 socket server 所監聽的 port number
        public SocketClient(string inRemoteIpAddr, int inRemotePortNum)
        {
            this._RemoteIpAddress = inRemoteIpAddr;
            this._RemotePortNumber = inRemotePortNum;
        }

        #endregion


        #region public method

        /// 
        /// 連線至 socket server
        /// 
        public void Connect()
        {
            //初始化 socket client
            _TcpClient = new TcpClient();
            _TcpClient.Connect(_RemoteIpAddress, _RemotePortNumber);
            sMessages.Add("Client Socket Program - Server Connected ...");
        }


        /// 
        /// 傳送訊息至 socker server
        /// 
        /// 
訊息
        /// socker server 回傳結果
        public string Send(string inMessage)
        {
            try
            {
                //取得用來傳送訊息至 socket server 的 stream 物件
                NetworkStream serverStream = _TcpClient.GetStream();

                //將資料轉為 byte[]
                byte[] outStream = System.Text.Encoding.UTF8.GetBytes(inMessage);

                //將資料寫入 stream object (表示傳送資料至 socket server)
                serverStream.Write(outStream, 0, outStream.Length);
                serverStream.Flush();

                //讀取 socket server 回傳值並轉為 string
                byte[] inStream = new byte[10025];
                serverStream.Read(inStream, 0, (int)_TcpClient.ReceiveBufferSize);
                string returndata = System.Text.Encoding.UTF8.GetString(inStream);

                sMessages.Add("Data from Server : " + returndata);
                return returndata;
            }
            catch (Exception exp)
            {
                sMessages.Add(exp.ToString());
                return exp.ToString();
            }
        }

        #endregion
    }
}