C#利用服务器实现客户端之间通信

这两天在学习C#，C#高级编程真的是厚厚的一本书QAQ。

昨天看了一下里面的通信部分(其实还没怎么看),看了网上一些人的博客，自己在他们的博客基础上写了一个通信。

先来讲述下我自己对于整个Socket通信过程的理解，毕竟初学，说错见谅，知道错了会改正~

首先在服务端新建一个serverSocket，对其进行初始化（一般包含AddressFamily:IP地址类型，SocketType:Socket传输数据方式，ProtoType:传输协议）;

接着我们要设置server端要绑定的IP:port;然后开始监听，并设置最多同时监听多少个Client.

这时，服务端就在等待状态，直到某一个Client连接到这个ip:port上，这时serverSocket.Accept()工作，获得这个连接。（此时的连接是有地址信息的哦！记得保存）

获得连接之后，server就可以和这个Client进行通信了,当加入第二个Client（我们称其为ClientB）时，Server接收到ClientB的消息，可以将这个消息转发给前一个Client（我们称其为ClientA），当受到ClientA的消息，也可以转发给ClientB。这样就实现了Clients之间的通信了。（重点在保存连接信息！！）

那么现在贴上代码讲解：

Server端代码

 namespace SocketServer
 {
     class Program
     {
         private static byte[] result = new byte[];

         static Socket serverSocket;
         private static string client;
         private static Socket clientSocket;
         //我这里存了两个Client，因为自己电脑开了两个Client，不会有多的
         //理论上应该开一个Socket[]来保存信息，最好用一个二元组将client的信息和连接绑定起来
         //这样就可以实现断开连接后下次登陆还是可以识别是这个Client
         private static Socket clientSocketA=null;
         private static Socket clientSocketB=null;

         static void Main(string[] args)
         {
             Program.SetPort();
         }
         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();
             //进入监听状态
             Console.WriteLine("监听{0}成功", serverSocket.LocalEndPoint.ToString());
             //开启一个线程来监听客户端连接
             Thread myThread = new Thread(ListenClientConnect);
             myThread.Start();
             Console.ReadLine();

         }
         /// <summary>
         /// 监听客户端连接
         /// </summary>
         private static void ListenClientConnect()
         {
             while (true)
             {
                 //Client连接上后 得到这个连接
                 clientSocket = serverSocket.Accept();

                 //这里我因为只有两个Client，所以就简单写了
                 if (clientSocketA == null)
                 {
                     clientSocketA = clientSocket;
                 }
                 else if (clientSocketB == null)
                 {
                     clientSocketB = clientSocket;
                 }
                 else
                 {
                     //当其中一个断开了，又重新连接时，需要再次保存连接
                     if (clientSocketB.IsBound)
                     {
                         clientSocketA = clientSocketB;
                         clientSocketB = clientSocket;
                     }
                     else
                     {
                         clientSocketB = clientSocketA;
                         clientSocketA = clientSocket;
                     }

                 }
                 clientSocket.Send(Encoding.ASCII.GetBytes("say hello"));
                 //开个线程接收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("接受客户端{0}消息{1}", myClientSocket.RemoteEndPoint.ToString()
                     //    , Encoding.ASCII.GetString(result, 0, revceiveNumber));
                     Console.WriteLine(Encoding.ASCII.GetString(result, , revceiveNumber));
                     if (myClientSocket == clientSocketA)
                     {
                         Console.WriteLine("receive from A");
                         if (clientSocketB!=null&&clientSocketB.IsBound)
                         {
                             Console.WriteLine("a IS BOUND");
                             clientSocketB.Send(result, , revceiveNumber, SocketFlags.None);
                         }
                         else
                         {
                             myClientSocket.Send(Encoding.ASCII.GetBytes("the people is not online! Send Failed!"));
                             Console.WriteLine("对方不在线上，发送失败！");
                         }
                     }
                     else
                     {
                         Console.WriteLine("receive from B");
                         if (clientSocketA != null && clientSocketA.IsBound)
                         {
                             Console.WriteLine("a IS BOUND");
                             clientSocketA.Send(result, , revceiveNumber, SocketFlags.None);
                         }
                         else
                         {
                             myClientSocket.Send(Encoding.ASCII.GetBytes("the people is not online! Send Failed!"));
                             Console.WriteLine("对方不在线上，发送失败！");
                         }

                     }

                 }
                 catch(Exception ex)
                 {
                     Console.WriteLine(ex.Message);
                     myClientSocket.Shutdown(SocketShutdown.Both);
                     myClientSocket.Close();
                     break;

                 }
             }

         }
     }
 }

Client端代码(因为都差不多 就只贴一个了)

 namespace SocketClient
 {
     class Program
     {
         private static byte[] result = new byte[];
         private static Socket clientSocket;
         private static void ListenServer()
         {
             while (true)
             {
                 result = new byte[];
                 int receiveLength = clientSocket.Receive(result);

                 Console.WriteLine("{0}", Encoding.ASCII.GetString(result, , receiveLength));
             }

         }
         static void Main(string[] args)
         {

             IPAddress ip = IPAddress.Parse("127.0.0.1");
             clientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
             try
             {
                 clientSocket.Connect(ip, );
                 Console.WriteLine("连接成功！");

             }
             catch (Exception e)
             {
                 Console.WriteLine("连接失败！");
                 return;
             }
             Thread threadRead = new Thread(ListenServer);
             threadRead.Start();

             while(true)
             {
                 try
                 {
                     Thread.Sleep();
                     string sendMessage = Console.ReadLine();
                     clientSocket.Send(Encoding.ASCII.GetBytes("Sylvia:"+sendMessage));

                 }
                 catch (Exception ex)
                 {
                     clientSocket.Shutdown(SocketShutdown.Both);
                     clientSocket.Close();
                     break;
                 }

             }
             Console.WriteLine("发送完毕 按回车退出");
             Console.ReadKey();
         }
     }
 }

写的时候要特别注意一下Send信息的时候，注意byte[]的传输大小，很容易变成byte[]数组的大小而不是内容的大小。

这个大家就自己尝试吧