PHP过滤HTML标签的三种方法

在做项目的过程中，我们经常需要用到过滤一些html标签来实现提高数据的安全性，其实就是删除那些对应用程序有潜在危害的数据。它用于去除标签以及删除或编码不需要的字符。
首先分享一些比较常见的

$str=preg_replace("/<s*imgs+[^>]*?srcs*=s*('|")(.*?)\1[^>]*?/?s*>/i","", $str); //过滤img标签  

$str=preg_replace("/s+/","", $str); //过滤多余回车  

$str=preg_replace("/<[ ]+/si","<",$str); //过滤<__("<"号后面带空格)  

$str=preg_replace("/<!--.*?-->/si","",$str); //注释  

$str=preg_replace("/<(!.*?)>/si","",$str); //过滤DOCTYPE  

$str=preg_replace("/<(/?html.*?)>/si","",$str); //过滤html标签  

$str=preg_replace("/<(/?head.*?)>/si","",$str); //过滤head标签  

$str=preg_replace("/<(/?meta.*?)>/si","",$str); //过滤meta标签  

$str=preg_replace("/<(/?body.*?)>/si","",$str); //过滤body标签  

$str=preg_replace("/<(/?link.*?)>/si","",$str); //过滤link标签  

$str=preg_replace("/<(/?form.*?)>/si","",$str); //过滤form标签  

$str=preg_replace("/cookie/si","COOKIE",$str); //过滤COOKIE标签
// http://www.manongjc.com/article/1345.html
$str=preg_replace("/<(applet.*?)>(.*?)<(/applet.*?)>/si","",$str); //过滤applet标签  

$str=preg_replace("/<(/?applet.*?)>/si","",$str); //过滤applet标签  

$str=preg_replace("/<(style.*?)>(.*?)<(/style.*?)>/si","",$str); //过滤style标签  

$str=preg_replace("/<(/?style.*?)>/si","",$str); //过滤style标签  

$str=preg_replace("/<(title.*?)>(.*?)<(/title.*?)>/si","",$str); //过滤title标签  

$str=preg_replace("/<(/?title.*?)>/si","",$str); //过滤title标签  

$str=preg_replace("/<(object.*?)>(.*?)<(/object.*?)>/si","",$str); //过滤object标签  

$str=preg_replace("/<(/?objec.*?)>/si","",$str); //过滤object标签  

$str=preg_replace("/<(noframes.*?)>(.*?)<(/noframes.*?)>/si","",$str); //过滤noframes标签  

$str=preg_replace("/<(/?noframes.*?)>/si","",$str); //过滤noframes标签  

$str=preg_replace("/<(i?frame.*?)>(.*?)<(/i?frame.*?)>/si","",$str); //过滤frame标签  

$str=preg_replace("/<(/?i?frame.*?)>/si","",$str); //过滤frame标签  

$str=preg_replace("/<(script.*?)>(.*?)<(/script.*?)>/si","",$str); //过滤script标签  

$str=preg_replace("/<(/?script.*?)>/si","",$str); //过滤script标签  

$str=preg_replace("/javascript/si","Javascript",$str); //过滤script标签  

$str=preg_replace("/vbscript/si","Vbscript",$str); //过滤script标签  

$str=preg_replace("/on([a-z]+)s*=/si","On\1=",$str); //过滤script标签  

$str=preg_replace("/&#/si","&＃",$str); //过滤script标签  

更简单些的写法：

function delhtml($str){  //清除html标签
$st=-1; //开始
$et=-1; //结束
$stmp=array();
$stmp[]=" ";
$len=strlen($str);
for($i=0;$i<$len;$i++){
  $ss=substr($str,$i,1);
  if(ord($ss)==60){ //ord("<")==60 http://www.manongjc.com/article/1345.html
  $st=$i;
  }
  if(ord($ss)==62){ //ord(">")==62
  $et=$i;
  if($st!=-1){
   $stmp[]=substr($str,$st,$et-$st+1);
  }
  }
}
$str=str_replace($stmp,"",$str);
return $str;
} 

再来一个：

function clear_html_label($html)
{
$search = array ("'<script[^>]*?>.*?</script>'si", "'<[/!]*?[^<>]*?>'si", "'([rn])[s]+'", "'&(quot|#34);'i", "'&(amp|#38);'i", "'&(lt|#60);'i", "'&(gt|#62);'i", "'&(nbsp|#160);'i", "'&(iexcl|#161);'i", "'&(cent|#162);'i", "'&(pound|#163);'i", "'&(copy|#169);'i", "'&#(d+);'e");
$replace = array ("", "", "1", """, "&", "<", ">", " ", chr(161), chr(162), chr(163), chr(169), "chr(1)");
return preg_replace($search, $replace, $html);
}