先來(lái)講述下我自己對(duì)于整個(gè)Socket通信過(guò)程的理解，畢竟初學(xué)，說(shuō)錯(cuò)見(jiàn)諒，知道錯(cuò)了會(huì)改正~ 

首先在服務(wù)端新建一個(gè)serverSocket，對(duì)其進(jìn)行初始化（一般包含AddressFamily:IP地址類(lèi)型，SocketType:Socket傳輸數(shù)據(jù)方式，ProtoType:傳輸協(xié)議）; 

接著我們要設(shè)置server端要綁定的IP:port;然后開(kāi)始監(jiān)聽(tīng)，并設(shè)置最多同時(shí)監(jiān)聽(tīng)多少個(gè)Client.

這時(shí)，服務(wù)端就在等待狀態(tài)，直到某一個(gè)Client連接到這個(gè)ip:port上，這時(shí)serverSocket.Accept()工作，獲得這個(gè)連接。（此時(shí)的連接是有地址信息的哦！記得保存） 

獲得連接之后，server就可以和這個(gè)Client進(jìn)行通信了,當(dāng)加入第二個(gè)Client（我們稱(chēng)其為ClientB）時(shí)，Server接收到ClientB的消息，可以將這個(gè)消息轉(zhuǎn)發(fā)給前一個(gè)Client（我們稱(chēng)其為ClientA），當(dāng)受到ClientA的消息，也可以轉(zhuǎn)發(fā)給ClientB。這樣就實(shí)現(xiàn)了Clients之間的通信了。（重點(diǎn)在保存連接信息！！）

那么現(xiàn)在貼上代碼講解：

Server端代碼 

namespace SocketServer{  class Program  {    private static byte[] result = new byte[1024];       static Socket serverSocket;    private static string client;    private static Socket clientSocket;    //我這里存了兩個(gè)Client，因?yàn)樽约弘娔X開(kāi)了兩個(gè)Client，不會(huì)有多的    //理論上應(yīng)該開(kāi)一個(gè)Socket[]來(lái)保存信息，最好用一個(gè)二元組將client的信息和連接綁定起來(lái)    //這樣就可以實(shí)現(xiàn)斷開(kāi)連接后下次登陸還是可以識(shí)別是這個(gè)Client    private static Socket clientSocketA=null;    private static Socket clientSocketB=null;        static void Main(string[] args)    {      Program.SetPort(8885);    }    private static void SetPort(int port)    {      IPAddress ip = IPAddress.Parse("127.0.0.1");//set ip      serverSocket = new Socket(AddressFamily.InterNetwork,        SocketType.Stream, ProtocolType.Tcp);//initialize      serverSocket.Bind(new IPEndPoint(ip, port));//bind      serverSocket.Listen(10);      //進(jìn)入監(jiān)聽(tīng)狀態(tài)      Console.WriteLine("監(jiān)聽(tīng){0}成功", serverSocket.LocalEndPoint.ToString());      //開(kāi)啟一個(gè)線(xiàn)程來(lái)監(jiān)聽(tīng)客戶(hù)端連接      Thread myThread = new Thread(ListenClientConnect);      myThread.Start();      Console.ReadLine();    }    /// <summary>    /// 監(jiān)聽(tīng)客戶(hù)端連接    /// </summary>    private static void ListenClientConnect()    {      while (true)      {        //Client連接上后 得到這個(gè)連接        clientSocket = serverSocket.Accept();        //這里我因?yàn)橹挥袃蓚€(gè)Client，所以就簡(jiǎn)單寫(xiě)了        if (clientSocketA == null)        {          clientSocketA = clientSocket;        }        else if (clientSocketB == null)        {          clientSocketB = clientSocket;        }        else        {          //當(dāng)其中一個(gè)斷開(kāi)了，又重新連接時(shí)，需要再次保存連接          if (clientSocketB.IsBound)          {            clientSocketA = clientSocketB;            clientSocketB = clientSocket;          }          else          {            clientSocketB = clientSocketA;            clientSocketA = clientSocket;          }                  }        clientSocket.Send(Encoding.ASCII.GetBytes("say hello"));        //開(kāi)個(gè)線(xiàn)程接收Client信息        Thread receivedThread = new Thread(ReceiveMessage);        receivedThread.Start(clientSocket);      }    }       private static void ReceiveMessage(object clientSocket)    {      Socket myClientSocket = (Socket) clientSocket;            while (true)      {        try        {          int revceiveNumber = myClientSocket.Receive(result);          //Console.WriteLine("接受客戶(hù)端{(lán)0}消息{1}", myClientSocket.RemoteEndPoint.ToString()          //  , Encoding.ASCII.GetString(result, 0, revceiveNumber));          Console.WriteLine(Encoding.ASCII.GetString(result, 0, revceiveNumber));          if (myClientSocket == clientSocketA)          {            Console.WriteLine("receive from A");            if (clientSocketB!=null&&clientSocketB.IsBound)            {              Console.WriteLine("a IS BOUND");              clientSocketB.Send(result, 0, revceiveNumber, SocketFlags.None);            }            else            {              myClientSocket.Send(Encoding.ASCII.GetBytes("the people is not online! Send Failed!"));              Console.WriteLine("對(duì)方不在線(xiàn)上，發(fā)送失敗！");            }          }          else          {            Console.WriteLine("receive from B");            if (clientSocketA != null && clientSocketA.IsBound)            {              Console.WriteLine("a IS BOUND");              clientSocketA.Send(result, 0, revceiveNumber, SocketFlags.None);            }              else            {              myClientSocket.Send(Encoding.ASCII.GetBytes("the people is not online! Send Failed!"));              Console.WriteLine("對(duì)方不在線(xiàn)上，發(fā)送失敗！");            }          }                  }        catch(Exception ex)        {          Console.WriteLine(ex.Message);          myClientSocket.Shutdown(SocketShutdown.Both);          myClientSocket.Close();          break;        }      }    }  }}