string filePath = Server.MapPath("~/file/test.htm");      //獲取HTML代碼      string mailBody = FileHelper.FileToString(filePath);      XHtmlElement xh = new XHtmlElement(mailBody);      //獲取body的子集a標簽并且class="icon"      var link = xh.Descendants("body").ChildDescendants("a").Where(c => c.Attributes.Any(a => a.Key == "class" && a.Value == "icon")).ToList();      //獲取帶href的a元素      var links = xh.Descendants("a").Where(c => c.Attributes.Any(a => a.Key == "href")).ToList();      foreach (var r in links)      {        Response.Write(r.Attributes.Single(c => c.Key == "href").Value); //出輸href      }      //獲取第一個img      var img = xh.Descendants("img");      //獲取最近的第一個p元素以及與他同一級的其它p元素      var ps = xh.Descendants("p");

using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Text;using System.Text.RegularExpressions;namespace SyntacticSugar{  /// <summary>  /// ** 描述：html解析類  /// ** 創始時間：2015-4-23  /// ** 修改時間：-  /// ** 作者：sunkaixuan  /// ** qq：610262374 歡迎交流,共同提高 ,命名語法等寫的不好的地方歡迎大家的給出寶貴建議  /// </summary>  public class XHtmlElement  {    private string _html;    public XHtmlElement(string html)    {      _html = html;    }    /// <summary>    /// 獲取最近的相同層級的HTML元素    /// </summary>    /// <param name="elementName">等于null為所有元素</param>    /// <returns></returns>    public List<HtmlInfo> Descendants(string elementName = null)    {      if (_html == null)      {        throw new ArgumentNullException("html不能這空！");      }      var allList = RootDescendants(_html);      var reval = allList.Where(c => elementName == null || c.TagName.ToLower() == elementName.ToLower()).ToList();      if (reval == null || reval.Count == 0)      {        reval = GetDescendantsSource(allList, elementName);      }      return reval;    }    /// <summary>    /// 獲取第一級元素    /// </summary>    /// <param name="elementName"></param>    /// <returns></returns>    public List<HtmlInfo> RootDescendants(string html = null)    {      /*       * 業務邏輯:             * 1、獲取第一個html標簽一直找結尾標簽，如果在這個過程中遇到相同的標簽收尾標簽就要加1             * 2、第一個標簽取到后繼續第一步操作，找第2個元素 。。第N個元素       */      if (html == null) html = _html;      var firstTag = Regex.Match(html, "<.+?>");      List<string> eleList = new List<string>();      List<HtmlInfo> reval = new List<HtmlInfo>();      GetElementsStringList(html, ref eleList);      foreach (var r in eleList)      {        HtmlInfo data = new HtmlInfo();        data.OldFullHtml = r;        data.SameLeveHtml = html;        data.TagName = Regex.Match(r, @"(?<=/s{1}|/<)[a-z,A-Z]+(?=/>|/s)", RegexOptions.IgnoreCase).Value;        data.InnerHtml = Regex.Match(r, @"(?<=/>).+(?=<)", RegexOptions.Singleline).Value;        var eleBegin = Regex.Match(r, "<.+?>").Value;        var attrList = Regex.Matches(eleBegin, @"[a-z,A-Z]+/="".+?""").Cast<Match>().Select(c => new { key = c.Value.Split('=').First(), value = c.Value.Split('=').Last().TrimEnd('"').TrimStart('"') }).ToList();        data.Attributes = new Dictionary<string, string>();        if (attrList != null && attrList.Count > 0)        {          foreach (var a in attrList)          {            data.Attributes.Add(a.key, a.value);          }        }        reval.Add(data);      }      return reval;    }    #region private    private List<HtmlInfo> GetDescendantsSource(List<HtmlInfo> allList, string elementName)    {      foreach (var r in allList)      {        if (r.InnerHtml == null || !r.InnerHtml.Contains("<")) continue;        var childList = RootDescendants(r.InnerHtml).Where(c => elementName == null || c.TagName.ToLower() == elementName.ToLower()).ToList();        if (childList == null || childList.Count == 0)        {          childList = GetDescendantsSource(RootDescendants(r.InnerHtml), elementName);          if (childList != null && childList.Count > 0)            return childList;        }        else        {          return childList;        }      }      return null;    }    private void GetElementsStringList(string html, ref List<string> eleList)    {      HtmlInfo info = new HtmlInfo();      info.TagName = Regex.Match(html, @"(?<=/</s{0,5}|/<)([a-z,A-Z]+|h/d{1})(?=/>|/s)", RegexOptions.IgnoreCase).Value;      string currentTagBeginReg = @"</s{0,10}" + info.TagName + @".*?>";//獲取當前標簽元素開始標簽正則      string currentTagEndReg = @"/<//" + info.TagName + @"/>";//獲取當前標簽元素收尾標簽正則      if (string.IsNullOrEmpty(info.TagName)) return;      string eleHtml = "";      //情況1 <a/>      //情況2 <a></a>      //情況3 <a> 錯誤格式      //情況4endif      if (Regex.IsMatch(html, @"</s{0,10}" + info.TagName + "[^<].*?/>"))//單標簽      {        eleHtml = Regex.Match(html, @"</s{0,10}" + info.TagName + "[^<].*?/>").Value;      }      else if (!Regex.IsMatch(html, currentTagEndReg))//沒有收尾      {        if (Regex.IsMatch(html, @"/s{0,10}/</!/-/-/[if"))        {          eleHtml = GetElementString(html, @"/s{0,10}/</!/-/-/[if", @"/[endif/]/-/-/>", 1);        }        else        {          eleHtml = Regex.Match(html, currentTagBeginReg,RegexOptions.Singleline).Value;        }      }      else      {        eleHtml = GetElementString(html, currentTagBeginReg, currentTagEndReg, 1);      }      try      {        eleList.Add(eleHtml);        html = html.Replace(eleHtml, "");        html = Regex.Replace(html, @"</!DOCTYPE.*?>", "");        if (!Regex.IsMatch(html, @"^/s*$"))        {          GetElementsStringList(html, ref eleList);        }      }      catch (Exception ex)      {        throw new Exception("SORRY,您的HTML格式不能解析?。?！");      }    }    private string GetElementString(string html, string currentTagBeginReg, string currentTagEndReg, int i)    {      string newHtml = GetRegNextByNum(html, currentTagBeginReg, currentTagEndReg, i);      var currentTagBeginMatches = Regex.Matches(newHtml, currentTagBeginReg, RegexOptions.Singleline).Cast<Match>().Select(c => c.Value).ToList();      var currentTagEndMatches = Regex.Matches(newHtml, currentTagEndReg).Cast<Match>().Select(c => c.Value).ToList();      if (currentTagBeginMatches.Count == currentTagEndMatches.Count)      { //兩個簽標元素相等        return newHtml;      }      return GetElementString(html, currentTagBeginReg, currentTagEndReg, ++i);    }    private string GetRegNextByNum(string val, string currentTagBeginReg, string currentTagEndReg, int i)    {      return Regex.Match(val, currentTagBeginReg + @"((.*?)" + currentTagEndReg + "){" + i + "}?", RegexOptions.IgnoreCase | RegexOptions.Singleline).Value;    }    #endregion  }  public static class XHtmlElementExtendsion  {    /// <summary>    /// 獲取最近的相同層級的HTML元素    /// </summary>    /// <param name="elementName">等于null為所有元素</param>    /// <returns></returns>    public static List<HtmlInfo> Descendants(this IEnumerable<HtmlInfo> htmlInfoList, string elementName = null)    {      var html = htmlInfoList.First().InnerHtml;      XHtmlElement xhe = new XHtmlElement(html);      return xhe.Descendants(elementName);    }    /// <summary>    /// 獲取下級元素    /// </summary>    /// <param name="elementName"></param>    /// <returns></returns>    public static List<HtmlInfo> ChildDescendants(this IEnumerable<HtmlInfo> htmlInfoList, string elementName = null)    {      var html = htmlInfoList.First().InnerHtml;      XHtmlElement xhe = new XHtmlElement(html);      return xhe.RootDescendants(html).Where(c => elementName == null || c.TagName == elementName).ToList();    }    /// <summary>    /// 獲取父級    /// </summary>    /// <param name="htmlInfoList"></param>    /// <returns></returns>    public static List<HtmlInfo> ParentDescendant(this IEnumerable<HtmlInfo> htmlInfoList,string fullHtml)    {      var saveLeveHtml = htmlInfoList.First().SameLeveHtml;      string replaceGuid=Guid.NewGuid().ToString();      fullHtml = fullHtml.Replace(saveLeveHtml,replaceGuid);      var parentHtml = Regex.Match(fullHtml, @"<[^<]+?>[^<]*?" + replaceGuid + @".*?<//.+?>").Value;      parentHtml = parentHtml.Replace(replaceGuid, saveLeveHtml);      XHtmlElement xhe = new XHtmlElement(parentHtml);      return xhe.RootDescendants();    }  }  /// <summary>  /// html信息類  /// </summary>  public class HtmlInfo  {    /// <summary>    /// 元素名    /// </summary>    public string TagName { get; set; }    /// <summary>    /// 元素屬性    /// </summary>    public Dictionary<string, string> Attributes { get; set; }    /// <summary>    /// 元素內部html    /// </summary>    public string InnerHtml { get; set; }    public string OldFullHtml { get; set; }    public string SameLeveHtml { get; set; }    /// <summary>    /// 得到元素的html    /// </summary>    /// <returns></returns>    public string FullHtml    {      get      {        StringBuilder reval = new StringBuilder();        string attributesString = string.Empty;        if (Attributes != null && Attributes.Count > 0)        {          attributesString = string.Join(" ", Attributes.Select(c => string.Format("{0}=/"{1}/"", c.Key, c.Value)));        }        reval.AppendFormat("<{0} {2}>{1}</{0}>", TagName, InnerHtml, attributesString);        return reval.ToString();      }    }  }}

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head>  <title></title></head><body>  <a id="1">我是1</a>   <a id="2" class="icon">icon</a>  <img /></body></html>