tcp一般用于维持一个可信任的连接,比起udp更为安全可靠,在vs.net,分别有tcpclient和udpclient以及tcplistener,一般开发中基本可以满足需要，但是这个有个很大的弊端，对于维持一个时间较长的，相互交互的来说，数据处理不是很明朗，vs/net中还有一个socket类，用他来做一个客户／服务器段,同时在接发数据的时候，能相互独立，这需要一个异步通讯过程
先实现服务器段：
using System;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading;

// State object for reading client data asynchronously
namespace TcpServer
{
public class StateObject 
{
    // Client  socket.
    public Socket workSocket = null;
    // Size of receive buffer.
    public const int BufferSize = 1024;
    // Receive buffer.
    public byte[] buffer = new byte[BufferSize];
    // Received data string.
    public StringBuilder sb = new StringBuilder();  
}

public class AsynchronousSocketListener 
{
    // Thread signal.
    public static ManualResetEvent allDone = new ManualResetEvent(false);
    private static Socket listener;
    private int _port=9010;
    public AsynchronousSocketListener() 
    {
    }
    public  void StopListening() 
    {
        listener.Close(); 
    }
    public int Port
    {
        set
        {
        _port=value;
        }
    }
    public  void StartListening() 
    {
        // Data buffer for incoming data.
        byte[] bytes = new Byte[1024];

        // Establish the local endpoint for the socket.
        // The DNS name of the computer
        // running the listener is "host.contoso.com".
        IPHostEntry ipHostInfo = Dns.Resolve(Dns.GetHostName());
        IPAddress ipAddress = ipHostInfo.AddressList[0];
        IPEndPoint localEndPoint = new IPEndPoint(ipAddress, _port);

        // Create a TCP/IP socket.
        listener = new Socket(AddressFamily.InterNetwork,
            SocketType.Stream, ProtocolType.Tcp );

        // Bind the socket to the local endpoint and listen for incoming connections.
        try 
        {
            listener.Bind(localEndPoint);
            listener.Listen(100);

            while (true) 
            {
                // Set the event to nonsignaled state.
                allDone.Reset();

                // Start an asynchronous socket to listen for connections.
                Console.WriteLine("接收连接..");
                listener.BeginAccept( 
                    new AsyncCallback(AcceptCallback),
                    listener );

                // Wait until a connection is made before continuing.
                allDone.WaitOne();
            }

        } 
        catch (Exception e) 
        {
            Console.WriteLine(e.ToString());
        }

        Console.WriteLine("nPress ENTER to continue...");
        Console.Read();

    }

    private void AcceptCallback(IAsyncResult ar) 
    {
        // Signal the main thread to continue.
        allDone.Set();

        // Get the socket that handles the client request.
        Socket listener = (Socket) ar.AsyncState;
        Socket handler = listener.EndAccept(ar);

        // Create the state object.
        StateObject state = new StateObject();
        state.workSocket = handler;
        handler.BeginReceive( state.buffer, 0, StateObject.BufferSize, 0,
            new AsyncCallback(ReadCallback), state);
    }

    private  void ReadCallback(IAsyncResult ar) 
    {
        String content = String.Empty;

        // Retrieve the state object and the handler socket
        // from the asynchronous state object.
        StateObject state = (StateObject) ar.AsyncState;
        Socket handler = state.workSocket;
        int bytesRead=0 ;
        // Read data from the client socket.
        if(handler.Connected )
        {

            try
            {
                bytesRead = handler.EndReceive(ar);
            }
            catch(Exception ex)
            {
                handler.Close(); 
            }


            if (bytesRead  0) 
            {
                // There  might be more data, so store the data received so far.


                // Check for end-of-file tag. If it is not there, read 
                // more data.
                content = Encoding.ASCII.GetString(
                    state.buffer,0,bytesRead);
                if (content.Length0 && content.EndsWith("EOF")  ) 
                {
                    // All the data has been read from the 
                    // client. Display it on the console.
                    Console.WriteLine("从客户端收到 {0} bytes 数据. n Data : {1}",
                        content.Length, content );
                    // Echo the data back to the client.
                    Send(handler, "-数据确认,已经收到-EOF");
                } 
                else 
                {
                    // Not all data received. Get more.
                    handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
                        new AsyncCallback(ReadCallback), state);
                }
            }

        }

    }

    private void Send(Socket handler, String data) 
    {
        // Convert the string data to byte data using ASCII encoding.
        byte[] byteData = Encoding.UTF8.GetBytes(data);

        // Begin sending the data to the remote device.
        handler.BeginSend(byteData, 0, byteData.Length, 0,
            new AsyncCallback(SendCallback), handler);
    }

    private void SendCallback(IAsyncResult ar) 
    {
        try 
        {
            // Retrieve the socket from the state object.
            Socket handler = (Socket) ar.AsyncState;

            // Complete sending the data to the remote device.
            int bytesSent = handler.EndSend(ar);
            Console.WriteLine("发送 {0} bytes 到客户端.", bytesSent);

            handler.Shutdown(SocketShutdown.Both);
            handler.Close();

        } 
        catch (Exception e) 
        {
            Console.WriteLine(e.ToString());
        }
    }

    
}

}

具体调用如下：
string p="";
            AsynchronousSocketListener _server=new AsynchronousSocketListener();
            _server.StartListening();
            if((p=Console.ReadLine().ToLower() )!="exit" )
            {
                _server.StopListening(); 
            }


紧接着实现客户端，客户端稍微复杂点，用一个session类来维持一个会话过程，coder类实现多种编码，Ｄatagram类定义一个具体的数据报文，默认为６４个字节大小，

using System;
using System.Collections; 
using System.Runtime.InteropServices;
using System.Diagnostics;
using System.Net.Sockets;
using System.Net;
using System.Text;
using System.Threading; 
using System.Data; 
using System.Xml; 
using System.Xml.XPath; 
namespace Client
{

    #region 通讯对象
    public delegate void NetEvent(object sender, NetEventArgs e);
    public class CSocket
    {
        #region 字段

      
        /// summary
        /// 客户端与服务器之间的会话类
        /// /summary
        private Session _session;

        /// summary
        /// 客户端是否已经连接服务器
        /// /summary
        private bool _isConnected = false;
        private bool _isEcho = false;
        private StringBuilder sb=new StringBuilder(); 
        /// summary
        /// 接收数据缓冲区大小64K
        /// /summary
        public const int DefaultBufferSize = 64*1024;

        /// summary
        /// 报文解析器
        /// /summary
        private DatagramResolver _resolver;

        /// summary
        /// 通讯格式编码解码器
        /// /summary
        private Coder _coder;

        

        /// summary
        /// 接收数据缓冲区
        /// /summary
        private byte[] _recvDataBuffer = new byte[DefaultBufferSize];
        public  ManualResetEvent allDone = new ManualResetEvent(false);
        #endregion

        #region 事件定义

        //需要订阅事件才能收到事件的通知，如果订阅者退出，必须取消订阅

        /// summary
        /// 已经连接服务器事件
        /// /summary


        /// summary
        /// 接收到数据报文事件
        /// /summary
          public event NetEvent ReceivedDatagram;
          public event NetEvent DisConnectedServer;
    public event NetEvent ConnectedServer;
        /// summary
        /// 连接断开事件
        /// /summary

        #endregion

        #region 属性

        /// summary
        /// 返回客户端与服务器之间的会话对象
        /// /summary
        public Session ClientSession
        {
            get
            {
                return _session;
            }
        }

        /// summary
        /// 返回客户端与服务器之间的连接状态
        /// /summary
        public bool IsConnected
        {
            get
            {
                return _isConnected;
            }
        }
        public bool IsEchoBack
        {
            get
            {
                return _isEcho;
            }
        }
        /// summary
        /// 数据报文分析器
        /// /summary
        public DatagramResolver Resovlver
        {
            get
            {
                return _resolver;
            }
            set
            {
                _resolver = value;
            }
        }

        /// summary
        /// 编码解码器
        /// /summary

        public Coder ServerCoder
        {
            get
            {
                return _coder;
            }
        }
        #endregion

        #region 公有方法

        /// summary
        /// 默认构造函数,使用默认的编码格式
        /// /summary
        public CSocket()
        {
            _coder = new Coder( Coder.EncodingMothord.gb2312 );
        }
                /// summary
        /// 构造函数,使用一个特定的编码器来初始化
        /// /summary
        /// param name="_coder"报文编码器/param
        public CSocket( Coder coder )
        {
            _coder = coder;
        }

        /// summary
        /// 连接服务器
        /// /summary
        /// param name="ip"服务器IP地址/param
        /// param name="port"服务器端口/param
        public virtual void Connect( string ip, int port)
        {
            if(IsConnected)
            {
                            Close();
            }

            Socket newsock= new Socket(AddressFamily.InterNetwork,
                SocketType.Stream, ProtocolType.Tcp);

            IPEndPoint iep = new IPEndPoint( IPAddress.Parse(ip), port);
            newsock.BeginConnect(iep, new AsyncCallback(Connected), newsock);

        }

        /// summary
        /// 发送数据报文
        /// /summary
        /// param name="datagram"/param
        public virtual void Send( string datagram)
        {
            try
            {
                if(datagram.Length ==0 )
                {
                    return;
                }

                
allDone.WaitOne();
                //获得报文的编码字节
                byte [] data = _coder.GetEncodingBytes(datagram);
                _session.ClientSocket.BeginSend( data, 0, data.Length, SocketFlags.None,
                new AsyncCallback( SendDataEnd ), _session.ClientSocket);
            }

            catch(Exception ex)
            {
                Console.WriteLine(ex.ToString() ); 
            }

        }

        /// summary
        /// 关闭连接
        /// /summary
        public virtual void Close()
        {
            if(!_isConnected)
            {
                return;
            }

            _session.Close();

            _session = null;

            _isConnected = false;
        }

        #endregion 

        #region 受保护方法

        /// summary
        /// 数据发送完成处理函数
        /// /summary
        /// param name="iar"/param
        protected virtual void SendDataEnd(IAsyncResult iar)
        {

            try
            {

                Socket remote = (Socket)iar.AsyncState;
                int sent = remote.EndSend(iar);

            }
            catch(Exception ex)
            {
                Console.WriteLine(ex.ToString() ); 
            }


        }

        /// summary
        /// 建立Tcp连接后处理过程
        /// /summary
        /// param name="iar"异步Socket/param
        protected virtual void Connected(IAsyncResult iar)
        {

            Socket socket = (Socket)iar.AsyncState;
            //返回一个与之廉洁的连接
            socket.EndConnect(iar);

            //创建新的会话
            _session = new Session(socket);

            _isConnected = true;
            allDone.Set();

            
            try
            {
                _session.ClientSocket.BeginReceive(_recvDataBuffer, 0, 
                    DefaultBufferSize, SocketFlags.None,
                    new AsyncCallback(RecvData), socket);}
            catch(Exception ex)
            {
                socket.Close(); 
            }
        }

        /// summary
        /// 数据接收处理函数
        /// /summary
        /// param name="iar"异步Socket/param
        public string recevie()
        {
            return this.sb.ToString()  ;
        }



        protected virtual void RecvData(IAsyncResult iar)
        {
            Socket remote = (Socket)iar.AsyncState;

            try
            {
                string receivedData="" ;
                int recv = remote.EndReceive(iar);
                if(recv0)
                {
    receivedData = System.Text.Encoding.UTF8.GetString(_recvDataBuffer,0,recv )    ;

                    if(receivedData.EndsWith("EOF")  )
                    {
                        _isEcho=true;
                        sb.Append(receivedData); 
                        this._session.Datagram=  receivedData;
                        if(ReceivedDatagram==null)
                        {
                        ReceivedDatagram(this,new NetEventArgs(_session)  ) ;
                        }

                        Console.WriteLine(string.Format("{0},来自{1}",receivedData,_session.ClientSocket.RemoteEndPoint.ToString()  ) ) ;
                        this.allDone.Set();                            
                    }
                    else
                    {
                        Console.WriteLine("listen"); 
                        _session.ClientSocket.BeginReceive(_recvDataBuffer, 0, DefaultBufferSize, SocketFlags.None,
                            new AsyncCallback(RecvData), _session.ClientSocket);
                    }

                }

            

                
            }
            catch(SocketException ex)
            {
                Console.WriteLine(ex.ToString() ); 
            }

        }

        #endregion


    }

    /// summary
    /// 通讯编码格式提供者,为通讯服务提供编码和解码服务
    /// 你可以在继承类中定制自己的编码方式如:数据加密传输等
    /// /summary
    public class Coder
    {
        /// summary
        /// 编码方式
        /// /summary
        private EncodingMothord _encodingMothord;

        protected Coder()
        {

        }

        public Coder(EncodingMothord encodingMothord)
        {
            _encodingMothord = encodingMothord;
        }

        public enum EncodingMothord
        {
            gb2312=0,
            Default ,
            Unicode,
            UTF8,
            ASCII,
        }

        /// summary
        /// 通讯数据解码
        /// /summary
        /// param name="dataBytes"需要解码的数据/param
        /// returns编码后的数据/returns
        public virtual string GetEncodingString( byte [] dataBytes,int size)
        {
            switch( _encodingMothord ) 
            {
                case EncodingMothord.gb2312:
                {
                    return Encoding.GetEncoding("gb2312").GetString(dataBytes,0,size);
                }
                case EncodingMothord.Default:
                {
                    return Encoding.Default.GetString(dataBytes,0,size);
                }
                case EncodingMothord.Unicode:
                {
                    return Encoding.Unicode.GetString(dataBytes,0,size);
                }
                case EncodingMothord.UTF8:
                {
                    return Encoding.UTF8.GetString(dataBytes,0,size);
                }
                case EncodingMothord.ASCII:
                {
                    return Encoding.ASCII.GetString(dataBytes,0,size);
                }
                default:
                {
                    throw( new Exception("未定义的编码格式"));
                }
            }

        }

        /// summary
        /// 数据编码
        /// /summary
        /// param name="datagram"需要编码的报文/param
        /// returns编码后的数据/returns
        public virtual byte[] GetEncodingBytes(string datagram)
        {
            switch( _encodingMothord) 
            {
                case EncodingMothord.gb2312:
                {
                    return Encoding.GetEncoding("gb2312").GetBytes(datagram);
                }
                case EncodingMothord.Default:
                {
                    return Encoding.Default.GetBytes(datagram);
                }
                case EncodingMothord.Unicode:
                {
                    return Encoding.Unicode.GetBytes(datagram);
                }
                case EncodingMothord.UTF8:
                {
                    return Encoding.UTF8.GetBytes(datagram);
                }
                case EncodingMothord.ASCII:
                {
                    return Encoding.ASCII.GetBytes(datagram);
                }
                default:
                {
                    throw( new Exception("未定义的编码格式"));
                }
            }
        }

    }


    /// summary
    /// 数据报文分析器,通过分析接收到的原始数据,得到完整的数据报文.
    /// 继承该类可以实现自己的报文解析方法.
    /// 通常的报文识别方法包括:固定长度,长度标记,标记符等方法
    /// 本类的现实的是标记符的方法,你可以在继承类中实现其他的方法
    /// /summary
    public class DatagramResolver
    {
        /// summary
        /// 报文结束标记
        /// /summary
        private string endTag;

        /// summary
        /// 返回结束标记
        /// /summary
        string EndTag
        {
            get
            {
                return endTag;
            }
        }

        /// summary
        /// 受保护的默认构造函数,提供给继承类使用
        /// /summary
        protected DatagramResolver()
        {

        }

        /// summary
        /// 构造函数
        /// /summary
        /// param name="endTag"报文结束标记/param
        public DatagramResolver(string endTag)
        {
            if(endTag == null)
            {
                throw (new ArgumentNullException("结束标记不能为null"));
            }

            if(endTag == "")
            {
                throw (new ArgumentException("结束标记符号不能为空字符串"));
            }

            this.endTag = endTag;
        }

        /// summary
        /// 解析报文
        /// /summary
        /// param name="rawDatagram"原始数据,返回未使用的报文片断,
        /// 该片断会保存在Session的Datagram对象中/param
        /// returns报文数组,原始数据可能包含多个报文/returns
        public virtual string [] Resolve(ref string rawDatagram)
        {
            ArrayList datagrams  = new ArrayList();

            //末尾标记位置索引
            int tagIndex =-1;

            while(true)
            {
                tagIndex = rawDatagram.IndexOf(endTag,tagIndex+1);

                if( tagIndex == -1 )
                {
                    break;
                }
                else
                {
                    //按照末尾标记把字符串分为左右两个部分
                    string newDatagram = rawDatagram.Substring(
                        0, tagIndex+endTag.Length);

                    datagrams.Add(newDatagram);

                    if(tagIndex+endTag.Length = rawDatagram.Length)
                    {
                        rawDatagram="";

                        break;
                    }

                    rawDatagram = rawDatagram.Substring(tagIndex+endTag.Length,
                        rawDatagram.Length - newDatagram.Length);

                    //从开始位置开始查找
                    tagIndex=0;
                }
            }

            string [] results= new string[datagrams.Count];

            datagrams.CopyTo(results);

            return results;
        }

    }


    /// summary
    /// 客户端与服务器之间的会话类
    /// 
    /// 版本:  1.1
    /// 替换版本: 1.0
    /// 
    /// 说明:
    ///    会话类包含远程通讯端的状态,这些状态包括Socket,报文内容,
    ///    客户端退出的类型(正常关闭,强制退出两种类型)
    /// /summary
    public class Session:ICloneable
    {
        #region 字段

        /// summary
        /// 会话ID
        /// /summary
        private SessionId _id;

        /// summary
        /// 客户端发送到服务器的报文
        /// 注意:在有些情况下报文可能只是报文的片断而不完整
        /// /summary
        private string _datagram;

        /// summary
        /// 客户端的Socket
        /// /summary
        private Socket _cliSock;

        /// summary
        /// 客户端的退出类型
        /// /summary
        private ExitType _exitType;

        /// summary
        /// 退出类型枚举
        /// /summary
        public enum ExitType
        {
 &nbs