public static class PageExtens
    {
        /// <summary>
        /// 服务器端弹出alert对话框
        /// </summary>
        /// <param name="page">Page类</param>
        /// <param name="str_Message">提示信息</param>
        public static void Alert(this Page page, string str_Message)
        {
            page.ClientScript.RegisterStartupScript(page.GetType(), "", "<script>alert('" + str_Message + "');</script>");
        }

        /// <summary>
        /// 服务器端弹出alert对话框
        /// </summary>
        /// <param name="page">Page类</param>
        /// <param name="str_Message">提示信息</param>
        /// <param name="str_CtlNameOrPageUrl">获取焦点控件的Id值</param>
        public static void Alert(this Page page, string str_Message, string str_CtlNameOrPageUrl)
        {
            if (str_CtlNameOrPageUrl.IndexOf(".") >= 0)
            {
                page.ClientScript.RegisterStartupScript(page.GetType(), "", "<script>alert('" + str_Message + "');self.location='" + str_CtlNameOrPageUrl + "';</script>");
            }
            else
            {
                page.ClientScript.RegisterStartupScript(page.GetType(), "", "<script>alert('" + str_Message + "');document.forms(0)." + str_CtlNameOrPageUrl + ".focus();document.forms(0)." + str_CtlNameOrPageUrl + ".select();</script>");
            }
        }
    }