正则表达式抓取网页信息

     声明：此正则表达式只适用于.net ,使用的流程为发送http请求返回整个html网页，然后从此html页面抓取想要的数据。

第一部分：发送httpWebRequest 请求

//url 地址
HttpWebRequest request = (HttpWebRequest)WebRequest.Create("URL"));
            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            //浏览器类型设置
            request.UserAgent = "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0; SLCC1; .NET CLR 2.0.50727; .NET CLR 3.0.04506; .NET CLR 3.5.21022; .NET CLR 1.0.3705; .NET CLR 1.1.4322)";
            StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.GetEncoding("UTF-8"));
              //返回的html网页数据
            String htmlStr = reader.ReadToEnd();

  第二部分：根据返回的html获取有用数据，此方法适用于所有想通过ID或Class等等的标签找到html的需求，拿下面一个方法为例

	/// <summary>
        /// 获得颜色
         /// </summary>
        /// <param name="htmlStr"></param>
        /// <returns></returns>
        public String getColor(String htmlStr)
        {
  //获取class为  DetailsC_Sku的html ，还可改为ID的方式   
//string regstr6 = @"<(?<HtmlTag>[\w]+)[^>]*\s[iI][dD]=(?<Quote>";    
string regstr6 = @"<(?<HtmlTag>[\w]+)[^>]*\s[cC][lL][aA][sS][sS]=(?<Quote>";
            string regstr7 = "[\"']?)DetailsC_Sku(?(Quote)";
            string regstr8 = @"\k<Quote>)";
            string regstr9 = "[\"']?[^>]*>";
            string regstr10 = @"((?<Nested><\k<HtmlTag>[^>]*>)|</\k<HtmlTag>>(?<-Nested>)|.*?)*</\k<HtmlTag>>";
            StringBuilder sb2 = new StringBuilder();
            sb2.Append(regstr6);
            sb2.Append(regstr7);
            sb2.Append(regstr8);
            sb2.Append(regstr9);
            sb2.Append(regstr10);
	    //根据正则表达式获取的html
            String sizeHtml = Regex.Match(htmlStr, sb2.ToString(), RegexOptions.Singleline).ToString();
            if (!String.IsNullOrEmpty(sizeHtml))
            {
                String newhtml = htmlStr.Replace(sizeHtml, "");
                string regstr11 = @"<(?<HtmlTag>[\w]+)[^>]*\s[cC][lL][aA][sS][sS]=(?<Quote>";
                string regstr12 = "[\"']?)DetailsC_Sku(?(Quote)";
                string regstr13 = @"\k<Quote>)";
                string regstr14 = "[\"']?[^>]*>";
                string regstr15 = @"((?<Nested><\k<HtmlTag>[^>]*>)|</\k<HtmlTag>>(?<-Nested>)|.*?)*</\k<HtmlTag>>";
                StringBuilder sb3 = new StringBuilder();
                sb3.Append(regstr11);
                sb3.Append(regstr12);
                sb3.Append(regstr13);
                sb3.Append(regstr14);
                sb3.Append(regstr15);
                String colorHtml = Regex.Match(newhtml, sb3.ToString(), RegexOptions.Singleline).ToString();
                if (String.IsNullOrEmpty(colorHtml))
                    return "";

                //找出此colorHtml中的所有a 标签
                Regex regex2 = new Regex(@"<a.*?>[\s\S]*?<\/a>");
                MatchCollection mc2 = regex2.Matches(colorHtml);
                StringBuilder sbs = new StringBuilder();
                //循环找到颜色
                if (mc2.Count > 0)
                {
                    foreach (Match mm in mc2)
                    {
                        sbs.Append(RemoveHtml(mm.Value.ToString())).Append(",");
                    }
                }
                return sbs.ToString();
            }
            return "";
            
        }

 /// <summary>
       /// 替换字符串中的html标签为空返回标签里的内容
        /// </summary>
        /// <param name="src"></param>
        /// <returns></returns>
        public string RemoveHtml(string src)
        {
            Regex htmlReg = new Regex(@"<[^>]+>", RegexOptions.Compiled | RegexOptions.IgnoreCase);
            Regex htmlSpaceReg = new Regex("\\&nbsp\\;", RegexOptions.Compiled | RegexOptions.IgnoreCase);
            Regex spaceReg = new Regex("\\s{2,}|\\ \\;", RegexOptions.Compiled | RegexOptions.IgnoreCase);
            Regex styleReg = new Regex(@"<style(.*?)</style>", RegexOptions.Compiled | RegexOptions.IgnoreCase);
            Regex scriptReg = new Regex(@"<script(.*?)</script>", RegexOptions.Compiled | RegexOptions.IgnoreCase);

            src = styleReg.Replace(src, string.Empty);
            src = scriptReg.Replace(src, string.Empty);
            src = htmlReg.Replace(src, string.Empty);
            src = htmlSpaceReg.Replace(src, " ");
            src = spaceReg.Replace(src, " ");
            return src.Trim();
        }