C#获取HTML文本的第一张图片与截取内容摘要示例代码

#region 获取第一张图片
/// <summary>
/// 获取HTML文本的图片地址
/// </summary>
/// <param name="content"></param>
/// <returns></returns>/
/// 
public ArrayList getimgurl(string html)
{
  ArrayList resultStr = new ArrayList();
  Regex r = new Regex(@"<IMG[^>] src=s*(?:´(?<src>[^´] )´|""(?<src>[^""] )""|(?<src>[^>s] ))s*[^>]*>", RegexOptions.IgnoreCase);//忽视大小写
  MatchCollection mc = r.Matches(html);

  foreach (Match m in mc)
  {
    resultStr.Add(m.Groups["src"].Value.ToLower());
  }
  if (resultStr.Count > 0)
  {
    return resultStr;
  }
  else
  {
    resultStr.Clear();
    return resultStr;
  }
}
#endregion

 #region 新闻内容摘要
/// <summary>
/// 新闻内容摘要
/// </summary>
/// <param name="sString"></param>
/// <param name="nLeng"></param>
/// <returns></returns>
public string GetContentSummary(string content, int length, bool StripHTML)
{
  if (string.IsNullOrEmpty(content) || length == 0)
    return "";
  if (StripHTML)
  {
    Regex re = new Regex("<[^>]*>");
    content = re.Replace(content, "");
    content = content.Replace("　", "").Replace(" ", "");
    if (content.Length <= length)
      return content;
    else
      return content.Substring(0, length)  "……";
  }
  else
  {
    if (content.Length <= length)
      return content;

    int pos = 0, npos = 0, size = 0;
    bool firststop = false, notr = false, noli = false;
    StringBuilder sb = new StringBuilder();
    while (true)
    {
      if (pos >= content.Length)
        break;
      string cur = content.Substring(pos, 1);
      if (cur == "<")
      {
        string next = content.Substring(pos  1, 3).ToLower();
        if (next.IndexOf("p") == 0 && next.IndexOf("pre") != 0)
        {
          npos = content.IndexOf(">", pos)  1;
        }
        else if (next.IndexOf("/p") == 0 && next.IndexOf("/pr") != 0)
        {
          npos = content.IndexOf(">", pos)  1;
          if (size < length)
            sb.Append("<br/>");
        }
        else if (next.IndexOf("br") == 0)
        {
          npos = content.IndexOf(">", pos)  1;
          if (size < length)
            sb.Append("<br/>");
        }
        else if (next.IndexOf("img") == 0)
        {
          npos = content.IndexOf(">", pos)  1;
          if (size < length)
          {
            sb.Append(content.Substring(pos, npos - pos));
            size = npos - pos  1;
          }
        }
        else if (next.IndexOf("li") == 0 || next.IndexOf("/li") == 0)
        {
          npos = content.IndexOf(">", pos)  1;
          if (size < length)
          {
            sb.Append(content.Substring(pos, npos - pos));
          }
          else
          {
            if (!noli && next.IndexOf("/li") == 0)
            {
              sb.Append(content.Substring(pos, npos - pos));
              noli = true;
            }
          }
        }
        else if (next.IndexOf("tr") == 0 || next.IndexOf("/tr") == 0)
        {
          npos = content.IndexOf(">", pos)  1;
          if (size < length)
          {
            sb.Append(content.Substring(pos, npos - pos));
          }
          else
          {
            if (!notr && next.IndexOf("/tr") == 0)
            {
              sb.Append(content.Substring(pos, npos - pos));
              notr = true;
            }
          }
        }
        else if (next.IndexOf("td") == 0 || next.IndexOf("/td") == 0)
        {
          npos = content.IndexOf(">", pos)  1;
          if (size < length)
          {
            sb.Append(content.Substring(pos, npos - pos));
          }
          else
          {
            if (!notr)
            {
              sb.Append(content.Substring(pos, npos - pos));
            }
          }
        }
        else
        {
          npos = content.IndexOf(">", pos)  1;
          sb.Append(content.Substring(pos, npos - pos));
        }
        if (npos <= pos)
          npos = pos  1;
        pos = npos;
      }
      else
      {
        if (size < length)
        {
          sb.Append(cur);
          size ;
        }
        else
        {
          if (!firststop)
          {
            sb.Append("……");
            firststop = true;
          }
        }
        pos ;
      }

    }
    return sb.ToString();
  }
}
#endregion