/// <summary>
        /// 取得网站的根目录的URL
        /// </summary>
        /// <returns></returns>
        public static string GetRootURI()
        {
            string AppPath = "";
            HttpContext HttpCurrent = HttpContext.Current;
            HttpRequest Req;
            if (HttpCurrent != null)
            {
                Req = HttpCurrent.Request;

                string UrlAuthority = Req.Url.GetLeftPart(UriPartial.Authority);
                if (Req.ApplicationPath == null || Req.ApplicationPath == "/")
                    //直接安装在   Web   站点   
                    AppPath = UrlAuthority;
                else
                    //安装在虚拟子目录下   
                    AppPath = UrlAuthority + Req.ApplicationPath;
            }
            return AppPath;
        }