///  summary>去除HTML標記 
///     
///  /summary>   
///  param name="Htmlstring">包括HTML的源碼/param>   
///  returns>已經去除后的文字/returns>   
public static string GetNoHTMLString(string Htmlstring) 
{ 
  //刪除腳本   
  Htmlstring = Regex.Replace(Htmlstring, @"script[^>]*?>.*?/script>", "", RegexOptions.IgnoreCase); 
  //刪除HTML   
  Htmlstring = Regex.Replace(Htmlstring, @"(.[^>]*)>", "", RegexOptions.IgnoreCase); 
  Htmlstring = Regex.Replace(Htmlstring, @"([\r\n])[\s]+", "", RegexOptions.IgnoreCase); 
  Htmlstring = Regex.Replace(Htmlstring, @"-->", "", RegexOptions.IgnoreCase); 
  Htmlstring = Regex.Replace(Htmlstring, @"!--.*", "", RegexOptions.IgnoreCase); 

  Htmlstring = Regex.Replace(Htmlstring, @"(quot|#34);", "\"", RegexOptions.IgnoreCase); 
  Htmlstring = Regex.Replace(Htmlstring, @"(amp|#38);", "", RegexOptions.IgnoreCase); 
  Htmlstring = Regex.Replace(Htmlstring, @"(lt|#60);", "", RegexOptions.IgnoreCase); 
  Htmlstring = Regex.Replace(Htmlstring, @"(gt|#62);", ">", RegexOptions.IgnoreCase); 
  Htmlstring = Regex.Replace(Htmlstring, @"(nbsp|#160);", "  ", RegexOptions.IgnoreCase); 
  Htmlstring = Regex.Replace(Htmlstring, @"(iexcl|#161);", "\xa1", RegexOptions.IgnoreCase); 
  Htmlstring = Regex.Replace(Htmlstring, @"(cent|#162);", "\xa2", RegexOptions.IgnoreCase); 
  Htmlstring = Regex.Replace(Htmlstring, @"(pound|#163);", "\xa3", RegexOptions.IgnoreCase); 
  Htmlstring = Regex.Replace(Htmlstring, @"(copy|#169);", "\xa9", RegexOptions.IgnoreCase); 
  Htmlstring = Regex.Replace(Htmlstring, @"#(\d+);", "", RegexOptions.IgnoreCase); 

  Htmlstring.Replace("", ""); 
  Htmlstring.Replace(">", ""); 
  Htmlstring.Replace("\r\n", ""); 
  Htmlstring = HttpContext.Current.Server.HtmlEncode(Htmlstring).Trim(); 

  return Htmlstring; 
} 

/// summary>獲取顯示的字符串，可顯示HTML標簽，但把危險的HTML標簽過濾，如iframe,script等。 
///  
/// /summary> 
/// param name="str">未處理的字符串/param> 
/// returns>/returns> 
public static string GetSafeHTMLString(string str) 
{ 
  str = Regex.Replace(str, @"applet[^>]*?>.*?/applet>", "", RegexOptions.IgnoreCase); 
  str = Regex.Replace(str, @"body[^>]*?>.*?/body>", "", RegexOptions.IgnoreCase); 
  str = Regex.Replace(str, @"embed[^>]*?>.*?/embed>", "", RegexOptions.IgnoreCase); 
  str = Regex.Replace(str, @"frame[^>]*?>.*?/frame>", "", RegexOptions.IgnoreCase); 
  str = Regex.Replace(str, @"script[^>]*?>.*?/script>", "", RegexOptions.IgnoreCase); 
  str = Regex.Replace(str, @"frameset[^>]*?>.*?/frameset>", "", RegexOptions.IgnoreCase); 
  str = Regex.Replace(str, @"html[^>]*?>.*?/html>", "", RegexOptions.IgnoreCase); 
  str = Regex.Replace(str, @"iframe[^>]*?>.*?/iframe>", "", RegexOptions.IgnoreCase); 
  str = Regex.Replace(str, @"style[^>]*?>.*?/style>", "", RegexOptions.IgnoreCase); 
  str = Regex.Replace(str, @"layer[^>]*?>.*?/layer>", "", RegexOptions.IgnoreCase); 
  str = Regex.Replace(str, @"link[^>]*?>.*?/link>", "", RegexOptions.IgnoreCase); 
  str = Regex.Replace(str, @"ilayer[^>]*?>.*?/ilayer>", "", RegexOptions.IgnoreCase); 
  str = Regex.Replace(str, @"meta[^>]*?>.*?/meta>", "", RegexOptions.IgnoreCase); 
  str = Regex.Replace(str, @"object[^>]*?>.*?/object>", "", RegexOptions.IgnoreCase); 
  return str; 
}