UWP&WP8.1 中文网页字符乱码 字符乱码 UTF-8转GBK 解决方法

  async void Download()
        {
            /*新建HttpClient*/
            HttpClient web_ = new HttpClient();
            /*使用HttpClient的GetAsync方法下载*/
            var res = await web_.GetAsync(new Uri("http://dzs.qisuu.com/txt/%E6%AD%A6%E9%81%93%E7%B3%BB%E7%BB%9F%E4%B9%8B%E8%8D%89%E6%B0%91%E5%B4%9B%E8%B5%B7.txt"));
            /*注册桌面程序可使用的字符编码*/
            Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
            /*注册GBK*/
            Encoding encodingGbk = Encoding.GetEncoding("GBK");
            /*转换编码*/
            Stream StreamToReader = await res.Content.ReadAsStreamAsync(); 
            /*使用StreamReader的新实例：stream流，字符编码 */   
            StreamReader sr = new StreamReader(StreamToReader,encodingGbk);
            /*异步读取全部字符*/
            string Text = await sr.ReadToEndAsync();    
            /*赋值到TextBox控件*/     
            T.Text += Text;
        }

 HttpClient web_ = new HttpClient();
            var res = await web_.GetAsync(new Uri("http://dzs.qisuu.com/txt/%E6%AD%A6%E9%81%93%E7%B3%BB%E7%BB%9F%E4%B9%8B%E8%8D%89%E6%B0%91%E5%B4%9B%E8%B5%B7.txt"));           
            /*转换字符*/
            var Text = await res.Content.ReadAsStringAsync();
            box.Text = Text;