Csharp:HttpWebRequest

        /// <summary>
        ///  Define other methods and classes here
        /// </summary>
        /// <param name="url"></param>
        /// <param name="contentType"></param>
        /// <returns></returns>
        public static Task<string> MakeAsyncRequest(string contentType, string contenttxt, string mobile)
        {
            string url = "http://www.dusystem.com/UserServiceAPI";
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
            request.ContentType = contentType;
            request.Method = WebRequestMethods.Http.Post; //get
            request.Timeout = 20000;
            request.Proxy = null;
            byte[] data = System.Text.Encoding.GetEncoding("gbk").GetBytes("geovindu"); //System.Text.UnicodeEncoding.ASCII.GetBytes("geovindu");//UTF8  
            Base64Encoder myEncoder = new Base64Encoder(data);
            StringBuilder sb = new StringBuilder();
            sb.Append(myEncoder.GetEncoded());
            string msg = UrlEncode(contenttxt);            
            string content = string.Format("method={0}&isLongSms={1}&username={2}&password={3}&smstype={4}&mobile={5}&content={6}", "MS", 0, "geovindu", sb.ToString(), 0, mobile, msg);//
            byte[] bytes = Encoding.GetEncoding("gbk").GetBytes(content);
            request.ContentLength = bytes.Length;
            Stream os = request.GetRequestStream();
            //req.GetResponseAsync();

            os.Write(bytes, 0, bytes.Length);
            os.Close();
            //System.Net.WebResponse resp = req.GetResponse();
            WebResponse resp = request.GetResponse();
            
            Task<WebResponse> task = Task.Factory.FromAsync(
                request.BeginGetResponse,
                asyncResult => request.EndGetResponse(asyncResult),
                (object)null);

            return task.ContinueWith(t => ReadStreamFromResponse(resp, content));
        }

        /// <summary>
        /// 对内容进行编码
        /// </summary>
        /// <param name="str"></param>
        /// <returns></returns>
        private static string UrlEncode(string str)
        {
            StringBuilder sb = new StringBuilder();
            byte[] byStr = System.Text.Encoding.GetEncoding("gbk").GetBytes(str); //默认是System.Text.Encoding.Default.GetBytes(str)
            for (int i = 0; i < byStr.Length; i++)
            {
                sb.Append(@"%" + Convert.ToString(byStr[i], 16));
            }

            return (sb.ToString());
        }
        /// <summary>
        /// 
        /// </summary>
        /// <param name="response"></param>
        /// <returns></returns>
        private static string ReadStreamFromResponse(WebResponse response, string content)
        {
            Stream responseStream = response.GetResponseStream();
            using (StreamReader sr = new StreamReader(responseStream))
            {
                string strContent = sr.ReadToEnd();
                return strContent;
            }
        }



        delegate string SynchOperation(string value);
        /// <summary>
        /// 
        /// </summary>
        /// <param name="callback"></param>
        /// <param name="value"></param>
         void BeginTheSynchronousOperation(AsyncCallback callback, string value)
        {
            SynchOperation op = new SynchOperation(SynchronousOperation);
            op.BeginInvoke(value, callback, op);
        }
        /// <summary>
        /// 
        /// </summary>
        /// <param name="value"></param>
        /// <returns></returns>
         string SynchronousOperation(string value)
        {

            string str = "geovindu";
            Thread.Sleep(10000);
            str = str + value;
            return str;
        }
        /// <summary>
        /// 
        /// </summary>
        /// <param name="result"></param>
         void CallbackOperation(IAsyncResult result)
        {
            // get your delegate
            var ar = result.AsyncState as SynchOperation;
            // end invoke and get value
            var returned = ar.EndInvoke(result);
            Response.Write(returned);
            
        }
        /// <summary>
        /// 
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        protected void Button1_Click(object sender, EventArgs e)
        {
           BeginTheSynchronousOperation(CallbackOperation, this.TextBox1.Text.Trim());
            var task = MakeAsyncRequest("application/x-www-form-urlencoded", "geovindu", "1388888888");
            Response.Write(string.Format("Got response of {0}", task.Result));  //返回成功
        }