Windows Phone 平台上的 Post 到服务器时的数据传输

原作者的Code链接：http://postclient.codeplex.com/

类：DownloadStringCompletedEventArgs:EventArgs ，为DownloadStringCompleted事件提供数据：下载下来的数据资源，执行异步操作时引发的异常

    /// <summary>
    /// 为DownloadStringCompleted事件提供数据
    /// </summary>
    public class DownloadStringCompletedEventArgs:EventArgs
    {
        #region 属性

        /// <summary>
        /// 通过DownloadStringAsynchronous方法下载的数据
        /// </summary>
        public string Result { get; private set; }

        /// <summary>
        /// 执行异步操作时引发的异常
        /// </summary>
        public Exception Error { get; private set; }

        #endregion

        #region 构造方法

        /// <summary>
        /// 创建一个含有指定返回数据的实例
        /// </summary>
        /// <param name="result">通过DownloadStringAsynchronous方法下载的数据</param>
        public DownloadStringCompletedEventArgs(string result)
        {
            Result=result;
        }

        /// <summary>
        /// 创建一个含有指定异常的实例
        /// </summary>
        /// <param name="ex">执行异步操作时引发的异常</param>
        public DownloadStringCompletedEventArgs(Exception ex)
        {
            Error = ex;
        }
        #endregion
    }

类：PostClient ，主要实现方法，PostClient()，3重载； DownloadStringAsync(Uri address) ，实现资源加载

    /// <summary>
    /// 包含将数据传送到HTTP Post 网络请求 和 从 HTTP Post 网络请求接收数据的常用方法
    /// </summary>
    public class PostClient
    {

        #region 成员

        /// <summary>
        /// Post数据请求
        /// </summary>
        StringBuilder _postData = new StringBuilder();

        #endregion

        #region 事件

        /// <summary>
        /// 为DownloadStringCompleted 事件声明的委托
        /// </summary>
        /// <param name="sender">触发事件的对象</param>
        /// <param name="e">持有已下载好的数据的参数</param>
        public delegate void DownloadStringCompletedHandler(object sender, DownloadStringCompletedEventArgs e);

        /// <summary>
        /// 当异步资源下载操作完成是触发
        /// </summary>
        public event DownloadStringCompletedHandler DownloadStringCompleted;

        #endregion

        #region 构造方法

        /// <summary>
        /// 创建一个包含特殊参数的PostClient实例
        /// </summary>
        /// <param name="parameters">String格式的Post 参数。有效的字符串格式形如：“name=David&amp;psd=123456”</param>
        public PostClient(string parameters)
        {
            _postData.Append(parameters);
        }

        /// <summary>
        /// 创建一个包含特殊参数的PostClient实例
        /// </summary>
        /// <param name="parameters">String列表格式的Post 参数。有效的字符串格式形如：“name=Divad”</param>
        public PostClient(IList<string> parameters)
        {
            foreach (var element in parameters)
            {
                _postData.Append(string.Format("{0}&",element));
            }
        }

        /// <summary>
        /// 创建一个包含特殊参数的PostClient实例
        /// </summary>
        /// <param name="parameters">字典格式的Post参数，有效的字典格式形如：“<"name","Divad">,<"psd",123456>”</param>
        public PostClient(IDictionary<string, object> parameters)
        {
            foreach (var pair in parameters)
            {
                _postData.Append(string.Format("{0}={1}&",pair.Key,pair.Value));
            }
        }
        #endregion

        #region 公有方法

        /// <summary>
        /// 从string格式的指定Uri中下载资源
        /// </summary>
        /// <param name="address">提供资源的URi地址</param>
        public void DownloadStringAsync(Uri address)
        {
            HttpWebRequest request;

            try
            {
                request = (HttpWebRequest)WebRequest.Create(address);
                request.Method = "POST";
                request.ContentType = "application/x-www-form-urlencoded";
                request.BeginGetRequestStream(new AsyncCallback(RequestReady), request);
            }
            catch 86             {
                if (DownloadStringCompleted!=null)
                {
                    System.Windows.Deployment.Current.Dispatcher.BeginInvoke(delegate()
                    {
                        DownloadStringCompleted(this,new DownloadStringCompletedEventArgs(new Exception("创建HTTP POST请求时发生错误")));
                    });
                }
                throw;
            }
        }

        #endregion

        #region 私有方法

        /// <summary>
        /// 执行请求时准备执行的操作
        /// </summary>
        /// <param name="asyncResult">异步操作状态</param>
        private void RequestReady(IAsyncResult asyncResult)
        {
            HttpWebRequest request = asyncResult.AsyncState as HttpWebRequest;

            using (Stream stream=request.EndGetRequestStream(asyncResult))
            {
                using (StreamWriter writer=new StreamWriter(stream))
                {
                    writer.Write(_postData.ToString());
                    writer.Flush();
                }
            }

            request.BeginGetResponse(new AsyncCallback(ResponseReady), request);
        }

        /// <summary>
        /// 请求响应是准备执行的操作
        /// </summary>
        /// <param name="asyncResult"></param>
      private void ResponseReady(IAsyncResult asyncResult)
        {
            HttpWebRequest request = asyncResult.AsyncState as HttpWebRequest;
            HttpWebResponse response = null;

            try
            {
                response = (HttpWebResponse)request.EndGetResponse(asyncResult);

                string result = string.Empty;
                using (Stream responseStream=response.GetResponseStream())
                {
                    using (StreamReader reader=new StreamReader(responseStream))
                    {
                        result = reader.ReadToEnd();
                    }
                }

                if (DownloadStringCompleted!=null)
                {
                    System.Windows.Deployment.Current.Dispatcher.BeginInvoke(delegate()
                    {
                        DownloadStringCompleted(this, new DownloadStringCompletedEventArgs(result));
                    });
                }
            }
            catch 
            {

                if (DownloadStringCompleted!=null)
                {
                    System.Windows.Deployment.Current.Dispatcher.BeginInvoke(delegate()
                    { 
                        DownloadStringCompleted(this,new DownloadStringCompletedEventArgs(new Exception("获取HTTP网络请求时发生错误！")));
                    });
                }
            }
        }
        #endregion
    }