HttpWebRequest request = (HttpWebRequest)WebRequest.Create(imgModel.SourceUrl);
            request.Referer = Request.UrlReferrer.ToString();
            request.UserAgent = Request.UserAgent;
            WebResponse response = request.GetResponse();
            Stream imgStream = response.GetResponseStream();

            if (imgStream != null)
            {
                Image img = Image.FromStream(imgStream, true, true);
                string extension = Common.GetImageFormat(img.RawFormat);
                //Bitmap bitmap = new Bitmap(img);//这里用bitmap方式保存也不行
                //bitmap.Save(Request.MapPath("/Images/" + Guid.NewGuid().ToString()) + extension, img.RawFormat);
                img.Save(Request.MapPath("/Images/" + Guid.NewGuid().ToString()) + extension, img.RawFormat);
                WriteAsCrossDomain(Request["jsoncallback"], string.Format("'宽：{0}，高：{1}'", img.Width, img.Height));
                img.Dispose();
                //bitmap.Dispose();
            }