制作wp7郵箱客戶端之socket基礎實現

　　在上一篇准備工作完成之后，我們對開發郵箱客戶端的原理有了基本的認識。那么來看看我們在wp7上有哪些資源來供我們開發吧，也就是說看看wp7對開發郵箱提供了哪些API支持。wp7沒有像android和。net framework上面的那種封裝好的imap類也沒有mail類，我們要自己做這些工作。

　　因為開發郵箱最基本的需求是在imap、stmp協議上的通信，他們屬於tcp家族中的一員，原理很簡單就是我對服務器發送一個指令，服務器針對指令做出響應，所以在這過程中需要用到通信的socket類，編碼解碼的encoding類，和多線程的控制，這些在wp7中都有了，好，我們可以開工了。

　　建一個基類tcpclientBase.cs 用來實現收發消息的基本功能

  abstract public class TCPClientBase : IDisposable
    {
        /// <summary>
        /// 端口
        /// </summary>
        const int IMAP_PORT = 143;

        /// <summary>
        /// 緩沖區大小
        /// </summary>
        const int MAX_BUFFER_READ_SIZE = 2048;

        /// <summary>
        /// 多線程通知超時時間
        /// </summary>
        const int TIMEOUT_MILLISECONDS = 5000;

        /// <summary>
        /// socket客戶端
        /// </summary>
        Socket _socket;

        protected static int IMAP_COMMAND_VAL = 0;

        static ManualResetEvent _clientDone = new ManualResetEvent(false);

        /// <summary>
        /// 是否連接
        /// </summary>
        public Boolean IsConnect
        {
            get
            {
                if (_socket != null)
                {
                    return _socket.Connected;
                }
                else
                    return false;
            }
        }

        /// <summary>
        /// 訪問終端
        /// </summary>
        EndPoint _dnsEndPoint;

        /// <summary>
        /// 構造函數
        /// </summary>
        /// <param name="HostName">主機名</param>
        public TCPClientBase(string HostName)
        {
            Initialization(new DnsEndPoint(HostName, IMAP_PORT));
        }

        /// <summary>
        /// 構造函數
        /// </summary>
        /// <param name="ipaddress">IP地址</param>
        public TCPClientBase(IPAddress ipaddress)
        {
            Initialization(new IPEndPoint(ipaddress, IMAP_PORT));
        }

        /// <summary>
        /// 實例化連接
        /// </summary>
        /// <param name="endPorint"></param>
        void Initialization(EndPoint endPorint)
        {
            _socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            _dnsEndPoint = endPorint;
            SocketAsyncEventArgs socketAsyncEventArgs = new SocketAsyncEventArgs()
            {
                RemoteEndPoint = _dnsEndPoint,
            };

            socketAsyncEventArgs.Completed += new EventHandler<SocketAsyncEventArgs>((o, e) =>
            {
                _clientDone.Set();
            });
            _clientDone.Reset();
            _socket.ConnectAsync(socketAsyncEventArgs);
            _clientDone.WaitOne(TIMEOUT_MILLISECONDS);
            ResponseReceivedResult result = this.Receive();
        }

        /// <summary>
        /// 發送消息
        /// </summary>
        /// <param name="data"></param>
        /// <param name="onComplete"></param>
        protected void Send(string data, Action<ResponseReceivedEventArgs> onComplete)
        {

            if (_socket == null)
            {
                throw new Exception("連接已關閉");
            }
            SocketAsyncEventArgs socketAsyncEventArgs = new SocketAsyncEventArgs() { RemoteEndPoint = _dnsEndPoint };
            byte[] byteDate = Encoding.UTF8.GetBytes(data);
            socketAsyncEventArgs.SetBuffer(byteDate, 0, byteDate.Length);
            socketAsyncEventArgs.Completed += new EventHandler<SocketAsyncEventArgs>((o, e) =>
            {
                ResponseReceivedEventArgs arg = new ResponseReceivedEventArgs();

                arg.isError = e.SocketError == SocketError.Success ? true : false;
                arg.response = string.Empty;
                if (onComplete != null)
                {
                    postUI(() =>
                    {
                        onComplete(arg);
                    });
                }
                _clientDone.Set();
            });
            _clientDone.Reset();
            _socket.SendAsync(socketAsyncEventArgs);
            _clientDone.WaitOne(TIMEOUT_MILLISECONDS);
        }

        /// <summary>
        /// 拋到UI主線程
        /// </summary>
        /// <param name="onComplete"></param>
        private static void postUI(Action onComplete)
        {
            System.Windows.Deployment.Current.Dispatcher.BeginInvoke(() =>
            {
                onComplete();
            });
        }

        /// <summary>
        /// 接收
        /// </summary>
        /// <returns></returns>
        protected ResponseReceivedResult Receive()
        {
            ResponseReceivedResult args = new ResponseReceivedResult();
            string response = "Time Out!";
            if (_socket == null)
            {
                throw new Exception("連接已關閉");
            }
            SocketAsyncEventArgs socketArgs = new SocketAsyncEventArgs() { RemoteEndPoint = _dnsEndPoint };
            socketArgs.SetBuffer(new byte[MAX_BUFFER_READ_SIZE], 0, MAX_BUFFER_READ_SIZE);
            socketArgs.Completed += new EventHandler<SocketAsyncEventArgs>((o, e) =>
            {

                if (e.SocketError == SocketError.Success)
                {
                    response = Encoding.UTF8.GetString(e.Buffer, e.Offset, e.BytesTransferred);
                    response = response.Trim('\0');
                    args.isError = true;
                }
                else
                    args.isError = false;
                _clientDone.Set();
            });
            _clientDone.Reset();
            _socket.ReceiveAsync(socketArgs);
            _clientDone.WaitOne(TIMEOUT_MILLISECONDS);
            args.response = response;
            return args;
        }

        protected virtual void Disconnect()
        {
            if (IsDisposed)
            {
                throw new ObjectDisposedException("TCPClientBase");
            }
            if (!IsConnect)
            {
                throw new InvalidOperationException("TCPClient is not connected");
            }
            _socket.Shutdown(SocketShutdown.Both);
            _socket.Close();
            _socket.Dispose();
            _clientDone.Dispose();
            _dnsEndPoint = null;
        }

        /// <summary>
        /// 實現dispose接口
        /// </summary>
        #region Dispose
        private bool IsDisposed = false;

        public void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        }

        protected virtual void Dispose(bool disposing)
        {
            lock (this)
            {
                if (!this.IsDisposed)
                {
                    if (disposing)
                    {
#warning 要做異常捕獲
                        Disconnect();
                    }
                    IsDisposed = true;
                }
            }
        }

        ~TCPClientBase()
        {
            Dispose(false);
        }
        #endregion
    }

然后繼承TCP類實現imap和smtp的功能……

待續……