pop3协议之二：tcp连接

 

         public  PopMailBox( string  username , string  password,  string  popserver,  int  port , int  delay)
        {
             this .username  =  username;
             this .password  =  password;
             this .popserver  =  popserver;
             this .port  =  port;
             this .delay  =  delay;
        }
         ///   <summary>
         ///  
         ///   </summary>
         ///   <param name="username"> pop服务器登陆名 </param>
         ///   <param name="password"> pop服务器登陆密码 </param>
         ///   <param name="popserver"> pop服务器名 </param>
         public  PopMailBox( string  username,  string  password,  string  popserver)
        {
             this .username  =  username;
             this .password  =  password;
             this .popserver  =  popserver;
        }
         ///   <summary>
         ///  
         ///   </summary>
         ///   <param name="username"> pop服务器登陆名 </param>
         ///   <param name="password"> pop服务器登陆密码 </param>
         ///   <param name="popserver"> pop服务器名 </param>
         ///   <param name="port"> pop服务器端口 </param>
         public  PopMailBox( string  username,  string  password,  string  popserver, int  port)
        {
             this .username  =  username;
             this .password  =  password;
             this .popserver  =  popserver;
             this .port  =  port;
        }

         public   bool  Connect()
        {
             try
            {
                client  =   new  TcpClient( popserver, port );
                isConnected  =   true ;
                 string  r  =  Receive();
                 if  (r.Length  >   0 )
                {
                     if  (r.IndexOf( " +OK " ) == 0 )
                         return   true ;
                     else
                    {
                        Error = " 响应协议不正确 " ;
                         return   false ;
                    }
                }
                 else
                {
                    Error = " 服务器无响应 " ;
                    isConnected  =   false ;
                    client.Close();
                     return   false ;
                    
                }
            }
             catch (Exception ex)
            {
                Error  =  ex.Message;
                 return   false ;
            }
        }

         public   void  Close()
        {
             if  (client  !=   null )
            {
                 if  ( this .isConnected)
                    Send( " quit " );
                client.Close();
            }
        }

         public   bool  Login()
        {
            Send( " user  "   +  username);
             if  (Receive().Substring( 0 , 3 ) == " +OK " )
            {
                Send( " pass  "   +  password);
                 if  (Receive().Substring( 0 , 3 ) == " +OK " )
                     return   true ;
                 else
                {
                    Send( " quit " );
                     this .Error  =   " 密码错误 " ;
                     return   false ;
                }
            }
             else
            {
                Send( " quit " );
                 this .Error = " 用户名错误 " ;
                 return   false ;
            }

                
        }

         public   void  Send( string  data)
        {
             byte [] buffer  =  Encoder.GetBytes(data  +   " \r\n " );
             if  ( this .isConnected)
            {
                client.GetStream().Write(buffer, 0 ,buffer.Length);
                debug  +=  data  +   " \n " ;
            }
        }

         public   string  Receive()
        {
//             return Receive(false);
             byte [] buffer;
             int  numberOfBytesRead;
             if  ( this .IsConnected)
            {
                buffer  =   new   byte [client.ReceiveBufferSize];
                 if  ((numberOfBytesRead = client.GetStream().Read(buffer, 0 ,buffer.Length))  !=   0 )
                {
                     return  Encoder.GetString(buffer, 0 ,numberOfBytesRead);
                }
                 else
                {
                     this .isConnected  =   false ;
                     this .Error  =   " 连接被断开 " ;
                     return   "" ;
                }
            }
             this .Error  =   " 尚未连接 " ;
             return   "" ;
        }

         public   string  Receive( bool  multiLine)
        {
             if  ( ! multiLine)
                 return  Receive();
             else
            {
                 string  endCondition;
                 string  result = String.Empty;
                 byte [] buffer;
                 int  numberOfBytesRead  =   0 ;
                 bool  finish  =   false ;
                DateTime startTime  =  DateTime.Now;
                endCondition  =   " .\r\n " ;
                 if  ( this .IsConnected  &&  Receive().Substring( 0 , 3 )  ==   " +OK " )
                {
                    buffer  =   new   byte [client.ReceiveBufferSize];
                     while  (  ! finish  &&  (numberOfBytesRead = client.GetStream().Read(buffer, 0 ,buffer.Length))  !=   0 )
                    {
                         string  temp  =  Encoder.GetString(buffer, 0 ,numberOfBytesRead);
                         if  (temp.IndexOf(endCondition)  >=   0 )
                        {
                            finish  =   true ;
                            temp  =  temp.Replace(endCondition, "" );
                        }
                        result  +=  temp;
                    }
                     if  ( numberOfBytesRead  ==   0 )
                         this .isConnected  =   false ;
                }
                 return  result;
            }
        }

         private   string  Stat()
        {
            Send( " stat " );
             return  Receive();
        }

         public   string  List()
        {
            Send( " list " );
             return  Receive( true );
        }

         public   string  Uidl( int  index)
        {
            Send( " uidl  "   +  index.ToString());
             return  Receive();
        }

         public   string  Uidl()
        {
            Send( " uidl " );
             return  Receive( true );
        }

         public   string  Dele(  int  index )
        {
            Send( " dele  "   +  index.ToString());
             return  Receive();
        }

         public   string  Retr( int  index)
        {
            Send( " retr  "   +  index.ToString());
             return  Receive( true );
        }