详细代码如下：

复制代码 代码如下:

<?php

abstract class Filter { //filter parent class

private $blackstr = array();

private $whitestr = array();

function filtit($str) {

//do something

}

}

class LoginFilter extends Filter { //for user login filte username(过滤注册的用户名)

function filtit($str) {

$this -> blackstr = array(

´/[x7f-xff]/´, //filter chinese include chinese symbol

´/W/´ //filter all english symbol

);

return preg_replace($this->blackstr, ´´, $str);

}

}

class EditorFilter extends Filter { //for article editor filter(过滤在线编辑器内容)

function filtit($str) {

$this -> blackstr = array(

´/&/´,

´/´/´,

´/"/´,

´/</´,

´/>/´,

´//´,

´///´,

´/-/´,

´/*/´,

´/ /´

);

$this -> whitestr = array(

´&´,

´'´,

´"´,

´<´,

´>´,

´\´,

´/´,

´-´,

´*´,

´´

);

return preg_replace($this->blackstr, $this -> whitestr, $str);

}

}

class SQLFilter extends Filter { //for filte sql query string(过滤如查询或其它sql语句)

function filtit($str) {

$this -> blackstr = array(

´/´/´,

´/-/´

);

return preg_replace($this->blackstr, ´´, $str);

}

}

class FileNameFilter extends Filter { //for filte a file name(过滤文件名如下载文件名)

function filtit($str) {

$this -> blackstr = array(

´/[^A-za-z0-9_.]||^|[|]/´

);

return preg_replace($this->blackstr, ´´, $str);

}

}

?>

使用方法如：

复制代码 代码如下:

$filter = new FileNameFilter(); //定义实例

$downFile = $filter->filtit($_GET[´fn´]); //调用过滤方法