private void Listen()
{
            //监听
            Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);//用tcp协议                      
            IPEndPoint local = new IPEndPoint(Dns.GetHostEntry (Dns.GetHostName()).AddressList[0], 8080);//监听8080端口  
            socket.Bind(local);
            socket.Listen(3);//允许3个客户连接  
            while (true)  //就是这个,判断的是什么?什么时候为真,什么时候为假???
            {                Socket accept = socket.Accept();//接受连接的客户                                
                BinaryFormatter bf;
                bf = new BinaryFormatter();
                MemoryStream stream = new MemoryStream();                Astruct ast = new Astruct();
                ast.seq = 4;
                ast.name = "接受中文了允许3个客户连接  ";
                ast.len = "接受连接的客户";
                ast.data = new char[] { 'd', 'a', 't', 'a' };
                bf.Serialize(stream, ast);
                byte[] buff = stream.ToArray();                accept.Send(buff, buff.Length, 0);
                accept.Close();            }  
 
 
        }