public String UploadImg(string from, string to, FileStream fileinfo)
        {
            Cookie         sId = RequstService.GetCookie("wxsid");
            Cookie         uIn = RequstService.GetCookie("wxuin");
            Cookie         webwx_data_ticket = RequstService.GetCookie("webwx_data_ticket");
            string         sKey              = LoginService.sKey;
            String         response          = "";
            Stream         inputStream       = null;
            Stream         inputStreamReader = null;
            BufferedStream bufferedReader    = null;

            HttpWebRequest conn = (HttpWebRequest)WebRequest.Create("https://file2.wx.qq.com/cgi-bin/mmwebwx-bin/webwxuploadmedia?f=json&sid=");

            try
            {
                System.Net.ServicePointManager.Expect100Continue = false;   //默认是true,所以导致错误
                //请求头参数
                String boundary = "----WebKitFormBoundary6oVvR66QUmo1TkXD"; //区分每个参数之间
                String freFix   = "--";
                String newLine  = "\r\n";

                // 请求主体
                StringBuilder sb = new StringBuilder();

                sb.Append(freFix + boundary).Append(newLine);     //这里注意多了个freFix,来区分去请求头中的参数
                sb.Append("Content-Disposition: form-data; name=\"id\"");
                sb.Append(newLine).Append(newLine);
                sb.Append(LoginService.GetTimeStamp()).Append(newLine);

                sb.Append(freFix + boundary).Append(newLine);
                sb.Append("Content-Disposition: form-data; name=\"name\"");
                sb.Append(newLine).Append(newLine);
                sb.Append(fileinfo.Name.Substring(fileinfo.Name.LastIndexOf("\\") + 1)).Append(newLine);

                sb.Append(freFix + boundary).Append(newLine);
                sb.Append("Content-Disposition: form-data; name=\"type\"");
                sb.Append(newLine).Append(newLine);
                sb.Append("image/png").Append(newLine);

                sb.Append(freFix + boundary).Append(newLine);
                sb.Append("Content-Disposition: form-data; name=\"lastModifiedDate\"");
                sb.Append(newLine).Append(newLine);
                sb.Append("Wed Mar 15 2017 18:13:15 GMT+0800").Append(newLine);

                sb.Append(freFix + boundary).Append(newLine);
                sb.Append("Content-Disposition: form-data; name=\"size\"");
                sb.Append(newLine).Append(newLine);
                sb.Append(fileinfo.Length).Append(newLine);

                sb.Append(freFix + boundary).Append(newLine);
                sb.Append("Content-Disposition: form-data; name=\"mediatype\"");
                sb.Append(newLine).Append(newLine);
                sb.Append("pic").Append(newLine);

                sb.Append(freFix + boundary).Append(newLine);
                sb.Append("Content-Disposition: form-data; name=\"uploadmediarequest\"");
                sb.Append(newLine).Append(newLine);
                sb.Append("{ \"UploadType\":2,\"BaseRequest\":{\"Uin\":" + uIn.Value + ",\"Sid\":\"" + sId.Value + "\",\"Skey\":\"" + sKey + "\",\"DeviceID\"://\"e823469202135602\"},\"ClientMediaId\": " + LoginService.GetTimeStamp() + ",\"TotalLen\":" + fileinfo.Length + ",\"StartPos\":0,\"DataLen/\":" + fileinfo.Length + ",\"MediaType\":4,\"FromUserName\":\"" + from + "\",\"ToUserName\":\"" + to + "\",\"FileMd5\":/\"7911968c2371ab9b72c3f42d52776ce9/\"}").Append(newLine);

                sb.Append(freFix + boundary).Append(newLine);
                sb.Append("Content-Disposition: form-data; name=\"webwx_data_ticket\"");
                sb.Append(newLine).Append(newLine);
                sb.Append(webwx_data_ticket.Value).Append(newLine);

                sb.Append(freFix + boundary).Append(newLine);
                sb.Append("Content-Disposition: form-data; name=\"pass_ticket\"");
                sb.Append(newLine).Append(newLine);
                sb.Append(LoginService.pass_Ticket).Append(newLine);

                sb.Append(freFix + boundary).Append(newLine);
                sb.Append("Content-Disposition: form-data; name=\"filename\"; filename=\"" + fileinfo.Name.Substring(fileinfo.Name.LastIndexOf("\\") + 1) + "\"");
                sb.Append(newLine);
                sb.Append("Content-Type: image/png");
                sb.Append(newLine).Append(newLine);
                sb.Append(freFix + boundary + freFix);

                conn.Method      = "POST";
                conn.Accept      = "*/*";
                conn.ContentType = "multipart/form-data; boundary=" + boundary;
                conn.UserAgent   = "Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/55.0.2883.87 Safari/537.36";
                conn.Referer     = "https://wx2.qq.com/?&lang=zh_CN";
                conn.Host        = "file2.wx.qq.com";
                conn.Headers.Add("Accept-Encoding", "gzip, deflate, br");
                conn.Headers.Add("Accept-Language", "zh-CN,zh;q=0.8");
                conn.Headers.Add("Cache-Control", "no-cache");
                //conn.Headers.Add("Connection", "Keep-Alive");
                conn.Headers.Add("Origin", "https://wx2.qq.com");
                conn.Headers.Add("Pragma", "no-cache");

                byte[] data = Encoding.UTF8.GetBytes(sb.ToString());
                // 输入文件流数据
                byte[] buffers = new Byte[checked ((uint)Math.Min(4096, (int)fileinfo.Length))];

                conn.ContentLength = data.Length + buffers.Length;
                int bytesRead = 0;
                using (Stream reqStream = conn.GetRequestStream())
                {
                    reqStream.Write(data, 0, data.Length);

                    while ((bytesRead = fileinfo.Read(buffers, 0, buffers.Length)) != 0)
                    {
                        reqStream.Write(buffers, 0, bytesRead);
                    }

                    reqStream.Close();
                }

                HttpWebResponse resp   = (HttpWebResponse)conn.GetResponse();
                Stream          stream = resp.GetResponseStream();
                string          result;
                //获取响应内容
                using (StreamReader reader = new StreamReader(stream, Encoding.UTF8))
                {
                    result = reader.ReadToEnd();
                }
                return(result);

                string url_1 = "https://file.wx.qq.com/cgi-bin/mmwebwx-bin/webwxuploadmedia?f=json&sid=";
                string url_2 = "https://file2.wx.qq.com/cgi-bin/mmwebwx-bin/webwxuploadmedia?f=json&sid=";
                //     HttpWebRequest conn11 = (HttpWebRequest)WebRequest.Create(url_1);
                //     conn11.Method = "POST";
                //     conn11.Accept = "*/*";
                //     conn11.ContentType = "multipart/form-data; boundary=" + boundary;
                //     conn11.UserAgent = "Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/55.0.2883.87 Safari/537.36";
                //     conn11.Referer = "https://wx2.qq.com/?&lang=zh_CN";
                //     conn11.Host = "file2.wx.qq.com";
                //     conn11.Headers.Add("Accept-Encoding", "gzip, deflate, br");
                //     conn11.Headers.Add("Accept-Language", "zh-CN,zh;q=0.8");
                //     conn11.Headers.Add("Cache-Control", "no-cache");
                //     //conn.Headers.Add("Connection", "Keep-Alive");
                //     conn11.Headers.Add("Origin", "https://wx2.qq.com");
                //     conn11.Headers.Add("Pragma", "no-cache");
                //
                //
                //     // 输入文件流数据
                //     byte[] buffers11 = new Byte[checked((uint)Math.Min(4096, (int)fileinfo.Length))];
                //
                //     string BaseRequest = "{" +
                //           "\"DeviceID\" : \"e441551176\"," +
                //           "\"Sid\" : \"" + sId.Value + "\"," +
                //           "\"Skey\" : \"" + LoginService.sKey + "\"," +
                //           "\"Uin\" : \"" + uIn.Value + "\"}";
                //     string fdic = "{" +
                //    "\"BaseRequest\" : " + BaseRequest + "," +
                //    "\"ClientMediaId\" : \"" + DateTime.Now.Millisecond + "\"," +
                //    "\"TotalLen\" : \"" + fileinfo.Length + "\"," +
                //    "\"StartPos\" : \"0\"," +
                //    "\"DataLen\" : \"" + fileinfo.Length + "\"," +
                //    "\"MediaType\" : \"4\"}";
                //
                //     string files = "{" +
                //  "\"id\":  \"WU_FILE_0\"," +
                //  "\"name\": \"temp\"," +
                //  "\"type\": \"image/png\"," +
                //  "\"lastModifiedDate\":\"Wed Mar 15 2017 18:13:15 GMT+0800\"," +
                //  "\"size\": \"" + fileinfo.Length + "\"," +
                //  "\"mediatype\":\"pic\"," +
                //  "\"uploadmediarequest\": " + fdic + "," +
                //  "\"webwx_data_ticket\": \"" + webwx_data_ticket.Value + "\"," +
                //  "\"pass_ticket\": \"" + LoginService.pass_Ticket + "\"," +
                //  "\"filename\": \"\"}";
                //     byte[] data11 = Encoding.UTF8.GetBytes(files.ToString());
                //     conn11.ContentLength = data11.Length + buffers11.Length;
                //     int bytesRead = 0;
                //     using (Stream reqStream = conn11.GetRequestStream())
                //     {
                //         reqStream.Write(data11, 0, data11.Length);
                //
                //         while ((bytesRead = fileinfo.Read(buffers11, 0, buffers11.Length)) != 0)
                //             reqStream.Write(buffers11, 0, bytesRead);
                //
                //         reqStream.Close();
                //     }
                //
                //     HttpWebResponse resp = (HttpWebResponse)conn11.GetResponse();
                //     Stream stream = resp.GetResponseStream();
                //     string result;
                //     //获取响应内容
                //     using (StreamReader reader = new StreamReader(stream, Encoding.UTF8))
                //     {
                //         result = reader.ReadToEnd();
                //     }
                // return result;

                //    byte[] bytesss = RequstService.SendPostRequest(_upload_image_url + sId.Value + "&lang=zh_CN&pass_ticket=" + LoginService.pass_Ticket, files);


                //        string send_result = Encoding.UTF8.GetString(bytesss);


                //    Stream outputStream = conn.GetRequestStream();
                // outputStream.Write(System.Text.Encoding.UTF8.GetBytes(sb.ToString()), 0, 0);//写入请求参数

                //    BinaryReader dis = new BinaryReader(fileinfo);
                //    int bytes = 0;
                //    byte[] bufferOut = new byte[1024];
                //    while ((bytes = dis.Read(bufferOut, 1, 1)) != -1)
                //    {
                //        outputStream.Write(bufferOut, 0, bytes);//写入图片
                //    }
                //
                //      outputStream.Write(System.Text.Encoding.UTF8.GetBytes(newLine), 0, 0);
                //      outputStream.Write(System.Text.Encoding.UTF8.GetBytes((freFix + boundary + freFix + newLine)), 0, 0);//标识请求数据写入结束
                //
                //     dis.Close();
                //    outputStream.Close();
                //
                HttpWebResponse response1       = (HttpWebResponse)conn.GetResponse();
                Stream          response_stream = response1.GetResponseStream();

                int    count  = (int)response1.ContentLength;
                int    offset = 0;
                byte[] buf    = new byte[count];
                while (count > 0)   //读取返回数据
                {
                    int n = response_stream.Read(buf, offset, count);
                    if (n == 0)
                    {
                        break;
                    }
                    count  -= n;
                    offset += n;
                }
                return(buf.ToString());


                if (RequstService.CookiesContainer == null)
                {
                    RequstService.CookiesContainer = new CookieContainer();
                }
                conn.CookieContainer = RequstService.CookiesContainer;  //启用cookie

                //读取响应信息
                inputStream       = conn.GetRequestStream();
                inputStreamReader = inputStream;
                bufferedReader    = new BufferedStream(inputStreamReader);
                String        str    = "";
                StringBuilder buffer = new StringBuilder();
                while ((str = bufferedReader.ToString()) != null)
                {
                    buffer.Append(str);
                }

                response = buffer.ToString();
            }
            catch (Exception e)
            {
                //  e.printStackTrace();
            }
            finally
            {
                if (conn != null)
                {
                    //   conn.cloas();
                }
                try
                {
                    bufferedReader.Close();
                    inputStreamReader.Close();
                    inputStream.Close();
                }
                catch (IOException execption)
                {
                }
            }
            return(response);
        }