获取请求Url

        /// <summary>
        /// 获取请求Url
        /// 例：http://www.text:1234
        /// </summary>
        /// <returns></returns>
        public string GetRequestUrl()
        {
            return string.Format("{0}://{1}", HttpContext.Current.Request.Url.Scheme,
                HttpContext.Current.Request.ServerVariables["HTTP_HOST"]);
        }