C#使用正则表达式抓取网站信息示例

public class JdRobber{  /// <summary>  /// 判断是否京东链接  /// </summary>  /// <param name="param"></param>  /// <returns></returns>  public bool ValidationUrl(string url)  {    bool result = false;    if (!String.IsNullOrEmpty(url))    {      Regex regex = new Regex(@"^http://item.jd.com//d+.html$");      Match match = regex.Match(url);      if (match.Success)      {        result = true;      }    }    return result;  }  /// <summary>  /// 抓取京东信息  /// </summary>  /// <param name="param"></param>  /// <returns></returns>  public void GetInfo(string url)  {    if (ValidationUrl(url))    {      string htmlStr = WebHandler.GetHtmlStr(url, "Default");      if (!String.IsNullOrEmpty(htmlStr))      {        string pattern = "";     //正则表达式        string sourceWebID = "";   //商品关键ID        string title = "";      //标题        decimal price = 0;      //价格        string picName = "";     //图片        //提取商品关键ID        pattern = @"http://item.jd.com/(?<Object>/d+).html";        sourceWebID = WebHandler.GetRegexText(url, pattern);        //提取标题        pattern = @"<div.*id=/""name/"".*>[/s/S]*<h1>(?<Object>.*?)</h1>";        title = WebHandler.GetRegexText(htmlStr, pattern);        //提取图片        int begin = htmlStr.IndexOf("<div id=/"spec-n1/"");        int end = htmlStr.IndexOf("</div>", begin + 1);        if (begin > 0 && end > 0)        {          string subPicHtml = htmlStr.Substring(begin, end - begin);          pattern = @"<img.*src=/""(?<Object>.*?)/"".*/>";          picName = WebHandler.GetRegexText(subPicHtml, pattern);        }        //提取价格        if (sourceWebID != "")        {          string priceUrl = @"http://p.3.cn/prices/get?skuid=J_" + sourceWebID + "&type=1";          string priceJson = WebHandler.GetHtmlStr(priceUrl, "Default");          pattern = @"/""p/"":/""(?<Object>/d+(/./d{1,2})?)/""";          price = WebHandler.GetValidPrice(WebHandler.GetRegexText(priceJson, pattern));        }        Console.WriteLine("商品名称：{0}", title);        Console.WriteLine("图片：{0}", picName);        Console.WriteLine("价格：{0}", price);      }    }  }}

/// <summary>/// 公共方法类/// </summary>public class WebHandler{  /// <summary>  /// 获取网页的HTML码  /// </summary>  /// <param name="url">链接地址</param>  /// <param name="encoding">编码类型</param>  /// <returns></returns>  public static string GetHtmlStr(string url, string encoding)  {    string htmlStr = "";    try    {      if (!String.IsNullOrEmpty(url))      {        WebRequest request = WebRequest.Create(url); //实例化WebRequest对象        WebResponse response = request.GetResponse(); //创建WebResponse对象        Stream datastream = response.GetResponseStream(); //创建流对象        Encoding ec = Encoding.Default;        if (encoding == "UTF8")        {          ec = Encoding.UTF8;        }        else if (encoding == "Default")        {          ec = Encoding.Default;        }        StreamReader reader = new StreamReader(datastream, ec);        htmlStr = reader.ReadToEnd(); //读取数据        reader.Close();        datastream.Close();        response.Close();      }    }    catch { }    return htmlStr;  }  /// <summary>  /// 获取正则表达式中的关键字  /// </summary>  /// <param name="input">文本</param>  /// <param name="pattern">表达式</param>  /// <returns></returns>  public static string GetRegexText(string input, string pattern)  {    string result = "";    if (!String.IsNullOrEmpty(input) && !String.IsNullOrEmpty(pattern))    {      Regex regex = new Regex(pattern, RegexOptions.IgnoreCase);      Match match = regex.Match(input);      if (match.Success)      {        result = match.Groups["Object"].Value;      }    }    return result;  }  /// <summary>  /// 返回有效价格  /// </summary>  /// <param name="strPrice"></param>  /// <returns></returns>  public static decimal GetValidPrice(string strPrice)  {    decimal price = 0;    try    {      if (!String.IsNullOrEmpty(strPrice))      {        Regex regex = new Regex(@"^/d+(/./d{1,2})?$", RegexOptions.IgnoreCase);        Match match = regex.Match(strPrice);        if (match.Success)        {          price = decimal.Parse(strPrice);        }      }    }    catch { }    return price;  }}