public static string QueryStringDecode(string key)

        {

            HttpRequest Request = System.Web.HttpContext.Current.Request;

            if (Regex.IsMatch(

                HttpUtility.UrlDecode(Request.Url.Query, Encoding.GetEncoding("iso-8859-1")),

                @"^(?:[\x00-\x7f]|[\xfc-\xff][\x80-\xbf]{5}|[\xf8-\xfb][\x80-\xbf]{4}|[\xf0-\xf7][\x80-\xbf]{3}|[\xe0-\xef][\x80-\xbf]{2}|[\xc0-\xdf][\x80-\xbf])+$"

            ))

            {

                return Request.QueryString[key];

            }

            else

            {

                System.Collections.Specialized.NameValueCollection Rq = HttpUtility.ParseQueryString(Request.Url.Query, System.Text.Encoding.GetEncoding("gb2312"));

                return Rq[key];

            }

        }