asp.net采集页面上所有图像图片资源的具体方法

/// <summary>  /// 下载指定ＵＲＬ下的所有图片  /// </summary>  public class WebPageImage  {    /// <summary>    /// 获取网页中全部图片    /// </summary>    /// <param name="url">网页地址</param>    /// <param name="charSet">网页编码，为空自动判断</param>    /// <returns>全部图片显示代码</returns>    public string getImages(string url, string charSet)    {      string s = getHtml(url, charSet);      return getPictures(s, url);    }    /// <summary>    /// 获取网页中全部图片    /// </summary>    /// <param name="url">网址</param>    /// <returns>全部图片代码</returns>    public string getImages(string url)    {      return getImages(url, "");    }    string doman(string url)    {      Uri u = new Uri(url);      return u.Host;    }    /// <summary>    /// 获取网页内容    /// </summary>    /// <param name="url">网站地址</param>    /// <param name="charSet">目标网页的编码,如果传入的是null或者"",那就自动分析网页的编码 </param>    /// <returns></returns>    string getHtml(string url, string charSet)    {      WebClient myWebClient = new WebClient();      //创建WebClient实例myWebClient       // 需要注意的：       //有的网页可能下不下来，有种种原因比如需要cookie,编码问题等等       //这是就要具体问题具体分析比如在头部加入cookie       // webclient.Headers.Add("Cookie", cookie);       //这样可能需要一些重载方法。根据需要写就可以了       //获取或设置用于对向 Internet 资源的请求进行身份验证的网络凭据。       myWebClient.Credentials = CredentialCache.DefaultCredentials;      //如果服务器要验证用户名,密码       //NetworkCredential mycred = new NetworkCredential(struser, strpassword);       //myWebClient.Credentials = mycred;       //从资源下载数据并返回字节数组。（加@是因为网址中间有"/"符号）       byte[] myDataBuffer = myWebClient.DownloadData(url);      string strWebData = Encoding.Default.GetString(myDataBuffer);      //获取网页字符编码描述信息       Match charSetMatch = Regex.Match(strWebData, "<meta([^<]*)charset=([^<]*)/"", RegexOptions.IgnoreCase | RegexOptions.Multiline);      string webCharSet = charSetMatch.Groups[2].Value.Replace("/"", "");      if (charSet == null || charSet == "")        charSet = webCharSet;      if (charSet != null && charSet != "" && Encoding.GetEncoding(charSet) != Encoding.Default)        strWebData = Encoding.GetEncoding(charSet).GetString(myDataBuffer);      return strWebData;    }    string getPictures(string data, string url)    {      MatchCollection ps = Regex.Matches(data, @"<img/b[^<>]*?/bsrc[/s/t/r/n]*=[/s/t/r/n]*[""']?[/s/t/r/n]*(?<imgUrl>[^/s/t/r/n""'<>]*)[^<>]*?/?[/s/t/r/n]*>");      string s = string.Empty;      for (int i = 0; i < ps.Count; i++)      {        pictures p = new pictures(ps[i].Value, url);        s += p.GetHtml + "<br />" + Environment.NewLine;      }      return s;    }    /// <summary>    /// 图片实体    /// 图片文件属性处理类    /// </summary>    public class pictures    {      public pictures(string strHtml, string baseUrl)      {        _html = strHtml;        Uri u1 = new Uri(baseUrl);        _doman = u1.Host;        _baseUrl = u1.Scheme + "://" + _doman;        setSrc();      }      private string _html = string.Empty;      private string _baseUrl = string.Empty;      private string _doman = string.Empty;      public string GetHtml      {        get { return _html; }      }      public string Alt      {        get        {          return GetAttribute("alt")[0];        }      }      public string Src      {        get        {          string s = GetAttribute("src")[0];          return s;        }      }      /// <summary>      /// 根据基路径把相对路径转换成绝对径      /// </summary>      /// <param name="baseUrl">基础路径</param>      /// <param name="u">待转换的相对路径</param>      /// <returns>绝对路径</returns>      public string absUrl(string baseUrl, string u)      {        Uri ub = new Uri(baseUrl);        Uri ua = new Uri(ub, u);        return ua.AbsoluteUri;      }      private void setSrc()      {        string strPattern = @"src[/s/t/r/n]*=[/s/t/r/n]*[""']?/S+[""']?";        string src = GetAttribute("src")[0].ToLower();        if (!(src.IndexOf("http://") == 0 || src.IndexOf("https://") == 0) && _baseUrl.Length > 10)        {          src = absUrl(_baseUrl, src);          string s = "src=/"" + src + "/"";          _html = Regex.Replace(_html, strPattern, s);        }      }      /// <summary>      /// 获取HTML代码中标签属性      /// </summary>      /// <param name="strHtml">HTML代码</param>      /// <param name="strAttributeName">属性名称</param>      /// <returns>属性值集合</returns>      private string[] GetAttribute(string strAttributeName)      {        List<string> lstAttribute = new List<string>();        string strPattern = string.Format(          @"{0}[/s/t/r/n]*=[/s/t/r/n]*[""']?/S+[""']?",          strAttributeName          );        MatchCollection matchs = Regex.Matches(_html, strPattern, RegexOptions.IgnoreCase);        foreach (Match m in matchs)        {          lstAttribute.Add(m.Value.Split('=')[1].Replace("/"", "").Replace("'", ""));        }        if (lstAttribute.Count == 0) lstAttribute.Add("");        return lstAttribute.ToArray();      }    }  }

new WebPageImage().getImages(http://www.sina.com)