取出文本中的图片

        ///   <summary>   
        ///    取出文本中的图片地址   
        ///   </summary>   
        ///   <param    name="HTMLStr">HTMLStr</param>   
        public static string GetImgUr_l(string HTMLStr)
        {
            string str = string.Empty;
            //string sPattern = @"^<img\s+[^>]*>";
            Regex r = new Regex(@"<img\s+[^>]*\s*src\s*=\s*([']?)(?<url>\S+)'?[^>]*>",
                    RegexOptions.Compiled);
            Match m = r.Match(HTMLStr.ToLower());
            if (m.Success)
                str = m.Result("${url}");
            return str;
        }