在留言板中，有时需要对用户输入内容进行过滤，将一些非法与特殊字符串进行过滤处理，将其替换为*。下面本篇文章就来给大家分享一下过滤功能的实现代码，希望对大家有所帮助！
需求：用户在评论页面输入非法字符以后，需要将非法字符替换为*
简单实现方法：
1、index.php
<!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>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>过滤留言板中的非法字符</title>
<style type="text/css">
<!--
body {
margin-left: 0px;
margin-top: 0px;
margin-right: 0px;
margin-bottom: 0px;
}
-->
</style></head>
<body>
<table width="1002" height="585" border="0" align="center" cellpadding="0" cellspacing="0">
<tr>
<td width="379" height="226"> </td>
<td width="445"> </td>
<td width="178"> </td>
</tr>
<form id="form1" name="form1" method="post" action="index_ok.php">
<tr>
<td height="260"> </td>
<td align="center" valign="top"><table width="430" border="1" cellpadding="1" cellspacing="1" bordercolor="#FFFFFF" bgcolor="#99CC67">
<tr>
<td width="81" height="30" align="right" bgcolor="#FFFFFF">发布主题：</td>
<td width="307" align="left" bgcolor="#FFFFFF"><input name="title" type="text" id="title" size="30" /></td>
</tr>
<tr>
<td align="right" bgcolor="#FFFFFF">发布内容：</td>
<td align="left" bgcolor="#FFFFFF"><textarea name="content" cols="43" rows="13" id="content"></textarea></td>
</tr>
</table></td>
<td> </td>
</tr>
<tr>
<td height="99"> </td>
<td align="center" valign="top"><table width="315" height="37" border="0" cellpadding="0" cellspacing="0">
<tr>
<td width="169" align="center"><input type="image" name="imageField" src="images/bg1.JPG" /></td>
<td width="146" align="center"><input type="image" name="imageField2" src="images/bg3.JPG" onclick="form.reset();return false;" /></td>
</tr>
</table></td>
<td> </td>
</tr>
</form>
</table>
</body>
</html>2、index_ok.php
<?php
$title=$_POST[title];
$content=$_POST[content];
$str="****";
$titles = preg_replace("/(黑客)|(抓包)|(监听)/",$str,$title);
$contents = preg_replace("/(黑客)|(抓包)|(监听)/",$str,$content);
?>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>过滤留言板中的非法字符</title>
<style type="text/css">
<!--
body {
margin-left: 0px;
margin-top: 0px;
margin-right: 0px;
margin-bottom: 0px;
}
.STYLE1 {
font-size: 12px;
color: #855201;
}
-->
</style></head>
<body>
<table width="1002" height="585" border="0" align="center" cellpadding="0" cellspacing="0">
<tr>
<td width="400" height="226"> </td>
<td width="406"> </td>
<td width="196"> </td>
</tr>
<form id="form1" name="form1" method="post" action="index_ok.php">
<tr>
<td height="260"> </td>
<td align="left" valign="top"><p class="STYLE1">发布主题：<?php echo $titles;?></p>
<p class="STYLE1">发布内容：<?php echo $contents;?></p></td>
<td> </td>
</tr>
<tr>
<td> </td>
<td align="center" valign="top"> </td>
<td> </td>
</tr>
</form>
</table>
</body>
</html>运行结果
复杂实现方法：可过滤JS 、PHP标签
//简单过滤JS 、PHP标签
function cleanJs($html){
$html=trim($html);
$html=str_replace(array('<?','?>'),array('<?','?>'),$html);
$pattern=array(
"'<script[^>]*?>.*?</script>'si",
"'<style[^>]*?>.*?</style>'si",
"'<frame[^>]*?>'si",
"'<iframe[^>]*?>.*?</iframe>'si",
"'<link[^>]*?>'si"
);
$replace=array("","","","","");
return preg_replace($pattern,$replace,$html);
}
/* Remove JS/CSS/IFRAME/FRAME 过滤JS/CSS/IFRAME/FRAME/XSS等恶意攻击代码(可安全使用)
* Return string
*/
function cleanJsCss($html){
$html=trim($html);
$html=preg_replace('/\0+/', '', $html);
$html=preg_replace('/(\\\\0)+/', '', $html);
$html=preg_replace('#(&\#*\w+)[\x00-\x20]+;#u',"\\1;",$html);
$html=preg_replace('#(&\#x*)([0-9A-F]+);*#iu',"\\1\\2;",$html);
$html=preg_replace("/%u0([a-z0-9]{3})/i", "&#x\\1;", $html);
$html=preg_replace("/%([a-z0-9]{2})/i", "&#x\\1;", $html);
$html=str_replace(array('<?','?>'),array('<?','?>'),$html);
$html=preg_replace('#\t+#',' ',$html);
$scripts=array('javascript','vbscript','script','applet','alert','document','write','cookie','window');
foreach($scripts as $script){
$temp_str="";
for($i=0;$i<strlen($script);$i++){
$temp_str.=substr($script,$i,1)."\s*";
}
$temp_str=substr($temp_str,0,-3);
$html=preg_replace('#'.$temp_str.'#s',$script,$html);
$html=preg_replace('#'.ucfirst($temp_str).'#s',ucfirst($script),$html);
}
$html=preg_replace("#<a.+?href=.*?(alert\(|alert&\#40;|javascript\:|window\.|document\.|\.cookie|<script|<xss).*?\>.*?</a>#si", "", $html);
$html=preg_replace("#<img .+?src=.*?(alert\(|alert&\#40;|javascript\:|window\.|document\.|\.cookie|<script|<xss).*?\ alt="How to filter illegal and special strings in php" >#si", "", $html);
$html=preg_replace("#<(script|xss).*?\>#si", "<\\1>", $html);
$html=preg_replace('#(<[^>]*?)(onblur|onchange|onclick|onfocus|onload|onmouseover|onmouseup|onmousedown|onselect|onsubmit|onunload|onkeypress|onkeydown|onkeyup|onresize)[^>]*>#is',"\\1>",$html);
//$html=preg_replace('#<(/*\s*)(alert|applet|basefont|base|behavior|bgsound|blink|body|embed|expression|form|frameset|frame|head|html|ilayer|iframe|input|layer|link|meta|object|plaintext|style|script|textarea|title|xml|xss)([^>]*)>#is', "<\\1\\2\\3>", $html);
$html=preg_replace('#<(/*\s*)(alert|applet|basefont|base|behavior|bgsound|blink|body|expression|form|frameset|frame|head|html|ilayer|iframe|input|layer|link|meta|object|plaintext|style|script|textarea|title|xml|xss)([^>]*)>#is', "<\\1\\2\\3>", $html);
$html=preg_replace('#(alert|cmd|passthru|eval|exec|system|fopen|fsockopen|file|file_get_contents|readfile|unlink)(\s*)\((.*?)\)#si', "\\1\\2(\\3)", $html);
$bad=array(
'document.cookie' => '',
'document.write' => '',
'window.location' => '',
"javascript\s*:" => '',
"Redirect\s+302" => '',
'<!--' => '<!--',
'-->' => '-->'
);
foreach ($bad as $key=>$val){
$html=preg_replace("#".$key."#i",$val,$html);
}
return $html;
}
//过滤html标签以及敏感字符
function cleanHtml($html){
return cleanYellow(htmlspecialchars($html));
}
//过滤部分HTML标签
function cleanFilter($html){
$html=trim($html);
$html=preg_replace("/<p[^>]*?>/is","<p>",$html);
$html=preg_replace("/<div[^>]*?>/is","<div>",$html);
$html=preg_replace("/<ul[^>]*?>/is","<ul>",$html);
$html=preg_replace("/<li[^>]*?>/is","<li>",$html);
$html=preg_replace("/<span[^>]*?/is","<span>",$html);
$html=preg_replace("/<a[^>]*?>(.*)?<\/a>/is","\${1}",$html);
$html=preg_replace("/<table[^>]*?>/is","<table>",$html);
$html=preg_replace("/<tr[^>]*?>/is","<tr>",$html);
$html=preg_replace("/<td[^>]*?>/is","<td>",$html);
$html=preg_replace("/<ol[^>]*?>/is","<ol>",$html);
$html=preg_replace("/<form[^>]*?>/is","",$html);
$html=preg_replace("/<input[^>]*?>/is","",$html);
return $html;
}
//过滤非法的敏感字符串
function cleanYellow($txt){
$txt=str_replace(
array("黄色","性爱","做爱","我日","我草","我靠","尻","共产党","胡锦涛","毛泽东",
"政府","中央","研究生考试","性生活","色情","情色","我考","麻痹","妈的","阴道",
"淫","奸","阴部","爱液","阴液","臀","色诱","煞笔","傻比","阴茎","法轮功","性交","阴毛","江泽民"),
array("*1*","*2*","*3*","*4*","*5*","*6*","*7*","*8*","*9*","*10*",
"*11*","*12*","*13*","*14*","*15*","*16*","*17*","*18*","*19*","*20*",
"*21*","*22*","*23*","*24*","*25*","*26*","*27*","*28*","*29*","*30*","*31*","*32*","*33*","*34*"),
$txt);
return $txt;
}
//过滤敏感字符串以及恶意代码
function cleanAll($html){
return cleanYellow(cleanJsCss($html));
}
//全半角字符替换
function setFilter($html){
$arr=array('０' => '0', '１' => '1', '２' => '2', '３' => '3', '４' => '4',
'５' => '5', '６' => '6', '７' => '7', '８' => '8', '９' => '9',
'Ａ' => 'A', 'Ｂ' => 'B', 'Ｃ' => 'C', 'Ｄ' => 'D', 'Ｅ' => 'E',
'Ｆ' => 'F', 'Ｇ' => 'G', 'Ｈ' => 'H', 'Ｉ' => 'I', 'Ｊ' => 'J',
'Ｋ' => 'K', 'Ｌ' => 'L', 'Ｍ' => 'M', 'Ｎ' => 'N', 'Ｏ' => 'O',
'Ｐ' => 'P', 'Ｑ' => 'Q', 'Ｒ' => 'R', 'Ｓ' => 'S', 'Ｔ' => 'T',
'Ｕ' => 'U', 'Ｖ' => 'V', 'Ｗ' => 'W', 'Ｘ' => 'X', 'Ｙ' => 'Y',
'Ｚ' => 'Z', 'ａ' => 'a', 'ｂ' => 'b', 'ｃ' => 'c', 'ｄ' => 'd',
'ｅ' => 'e', 'ｆ' => 'f', 'ｇ' => 'g', 'ｈ' => 'h', 'ｉ' => 'i',
'ｊ' => 'j', 'ｋ' => 'k', 'ｌ' => 'l', 'ｍ' => 'm', 'ｎ' => 'n',
'ｏ' => 'o', 'ｐ' => 'p', 'ｑ' => 'q', 'ｒ' => 'r', 'ｓ' => 's',
'ｔ' => 't', 'ｕ' => 'u', 'ｖ' => 'v', 'ｗ' => 'w', 'ｘ' => 'x',
'ｙ' => 'y', 'ｚ' => 'z',
'（' => '(', '）' => ')', '〔' => '[', '〕' => ']', '【' => '[',
'】' => ']', '〖' => '[', '〗' => ']', '“' => '[', '”' => ']',
'‘' => '[', '’' => ']', '｛' => '{', '｝' => '}', '《' => '<',
'》' => '>',
'％' => '%', '＋' => '+', '—' => '-', '－' => '-', '～' => '-',
'：' => ':', '。' => '.', '、' => ',', '，' => '.', '、' => '.',
'；' => ',', '？' => '?', '！' => '!', '…' => '-', '‖' => '|',
'”' => '"', '’' => '`', '‘' => '`', '｜' => '|', '〃' => '"',
' ' => ' ');
return strtr($html,$arr);
}推荐学习：《PHP视频教程》
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