public string szJson = "";
          byte[] json;
          UploadClass up = new UploadClass();
  
          public ValidatePage()
          {
              InitializeComponent();
          }
  
         private void PhoneApplicationPage_Loaded(object sender, RoutedEventArgs e)
         {
             //我做了一个实现上传某些关键的Json数据，返回服务器Appid的功能，类似新浪微博获取AccessToken，不过微博SDK已经封装好了上传功能，比我这个简单许多。
             GetAppid();
         }
 
         void GetAppid()
         {
             up.device = "Luma1020";
             up.devid = "abcdefghijklmn123456";
             up.os = "8.0";
             up.appid = "987654321asdfghjkl";
 
             DataContractJsonSerializer dc = new DataContractJsonSerializer(typeof(UploadClass)); 

             //序列化要发送的信息
             using (MemoryStream ms = new MemoryStream())
             {
                 dc.WriteObject(ms, up);  //报错的原因是UploadClass的类名没有写public
                 json = ms.ToArray();
                 ms.Close(); //一定要关闭流
                 szJson = Encoding.UTF8.GetString(json, 0, json.Length);  //服务器要求用UTF8，就在代码中转换成UTF8，要求用别的就转换成相应的格式。
             }
 
             //从这一步开始，准备向服务器发送数据。
             HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://api.xxxx.com/Api/xxxxx");
             request.Method = "POST";
             request.ContentType = "application/json";
             request.ContentLength = json.Length;
 
             IAsyncResult result = (IAsyncResult)request.BeginGetRequestStream(GetRequestCallback, request);
         }
 
         private void GetRequestCallback(IAsyncResult asyncResult)
         {
             HttpWebRequest request = (HttpWebRequest)asyncResult.AsyncState;
             using (Stream sm = request.EndGetRequestStream(asyncResult))
             {
                 sm.Write(json, 0, json.Length);
             }
             request.BeginGetResponse(GetResponseCallback, request);
         }
 
         void GetResponseCallback(IAsyncResult result)
         {
             Stream stream = null;
             UploadClass uc = null;  //new 一个供返回Json数据的实例
 
             HttpWebRequest req = (HttpWebRequest)result.AsyncState;
             WebResponse webresponse = req.EndGetResponse(result);
             stream = webresponse.GetResponseStream();
             using (StreamReader reader = new StreamReader(stream))
             {
                 string contents = reader.ReadToEnd();
 
                 uc = new UploadClass();
 
                 using (MemoryStream ms = new MemoryStream(Encoding.UTF8.GetBytes(contents.ToString())))
                 {
                     DataContractJsonSerializer ds = new DataContractJsonSerializer(typeof(UploadClass));
                     uc = (UploadClass)ds.ReadObject(ms);
                 }
             }
 
             //这种回调函数中不能直接在函数体里写UI的语句，需要用Dispatcher去通知UI改变。
             if (uc.code == "0")
             {
                 Dispatcher.BeginInvoke
                     (() =>
                     {
                        //这些都是前台UI，下面都是例子：
                         IDTextBlock.Text = "AppId:  " + up.id;
                         DeviceTextBlock.Text = "Device:  " + up.device;
                     }
                     );
             }
 
             else
             {
                 Dispatcher.BeginInvoke(() =>
                 {
                  //和上面一样，根据自己的UI自行设置。
                 });
             }
         }