/// <summary>
        /// 下載文件(jian)，同步支持本地和(he)URI的文件(jian)
        /// </summary>
        /// <param name="path"></param>
        /// <returns></returns>
        public ActionResult DownLoad(string path)
        {
            if (path.IndexOf("//") < 0)
            {
                string localPath = Server.MapPath("/" + path);
                string contentType = MimeMapping.GetMimeMapping(localPath);
                return File(localPath, contentType, "下載(zai)文件");
            }
            else
            {
                HttpWebRequest request = (HttpWebRequest)System.Net.WebRequest.Create(path);
                HttpWebResponse response = (HttpWebResponse)request.GetResponse();
                Stream stream = response.GetResponseStream();
                var contentType = response.ContentType;//獲(huo)得文件(jian)的(de)總大小
                return File(stream, contentType, "下載(zai)文件(jian)");
            }
        }