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);
        }