转换 Html 内容为纯文本内容（html,文本互转）

转自http://www.cnblogs.com/jyshi/archive/2011/08/09/2132762.html ；

  /// <summary>
  /// 转换纯文本内容为 HTML 内容
  /// </summary>
  /// <param name="Text">纯文本内容</param>
  /// <returns>转换后的 HTML 内容</returns>
  public static string ToHTML(string Text)
  {
      return Regex.Replace(Regex.Replace(Regex.Replace(Regex.Replace(Regex.Replace("<p>" + Text + "</p>", "\r\n", "</p><p>"), "\r", "</p><p>"), "\n", "<br />"), "\t", "    "), "  ", "  ");
  }
  /// <summary>
  /// 转换 Html 内容为纯文本内容
  /// </summary>
  /// <param name="HTML">HTML 内容</param>
  /// <returns>转换后的纯文本内容</returns>
  public static string ToText(string HTML)
  {
      string input = HTML;
      return Regex.Replace(Regex.Replace(Regex.Replace(Regex.Replace(Regex.Replace(Regex.Replace(input, @"(?m)<script[^>]*>(\w|\W)*?</script[^>]*>", "", RegexOptions.Multiline | RegexOptions.IgnoreCase), @"(?m)<style[^>]*>(\w|\W)*?</style[^>]*>", "", RegexOptions.Multiline | RegexOptions.IgnoreCase), @"(?m)<select[^>]*>(\w|\W)*?</select[^>]*>", "", RegexOptions.Multiline | RegexOptions.IgnoreCase), @"(?m)<a[^>]*>(\w|\W)*?</a[^>]*>", "", RegexOptions.Multiline | RegexOptions.IgnoreCase), "(<[^>]+?>)| ", "", RegexOptions.Multiline | RegexOptions.IgnoreCase), @"(\s)+", "", RegexOptions.Multiline | RegexOptions.IgnoreCase);
  }