public string UploadBase64Img()
        {
            try
            {
                string base64 = Request["imgUrl"];
                base64= base64.Substring(base64.IndexOf(",") + 1);      //将‘,’以前的多余字符串删除

                System.Drawing.Bitmap bitmap = null;//定义一个Bitmap对象，接收转换完成的图片

                byte[] byt64 = Convert.FromBase64String(base64);//将纯净资源Base64转换成等效的8位无符号整形数组
                MemoryStream ms = new MemoryStream(byt64);//转换成无法调整大小的MemoryStream对象
                bitmap = new System.Drawing.Bitmap(ms);//将MemoryStream对象转换成Bitmap对象
                ms.Close();//关闭当前流，并释放所有与之关联的资源

                // 文件上传后的保存路径
                string savePath = Server.MapPath("~/UploadImgs/");
                if (!Directory.Exists(savePath))
                {
                    Directory.CreateDirectory(savePath);
                }

                DateTime _now = DateTime.Now;
                var r = new Random();
                int n = r.Next(1000, 9999);
                string imgName = string.Format("{0}-{1}-{2}.png", _now.ToString("yyyy-MM-dd"), _now.Millisecond, n);//图片名称
                string imgPath = savePath + imgName;

                bitmap.Save(imgPath, System.Drawing.Imaging.ImageFormat.Png);//保存到服务器路径

                return imgName;
            }
            catch (Exception ex)
            {                
                throw ex;
            }
        }