php类过滤字符串函数(过滤非法字符)

<?php
class request
{
public  function __construct()
{
if(!get_magic_quotes_gpc())
{
if(!empty($_POST))
{
foreach ($_POST as $k => &$v)
{
if(is_array($v))
{
@array_walk($v, 'urldecode');
@array_walk($v, 'addslashes');
}
else
{
$v = addslashes(urldecode($v));
}
$p[$k] = $v;
}
$_POST = $p;
unset($p);
}
if(!empty($_GET))
{
foreach ($_GET as $k => &$v)
{
if(is_array($v))
{
@array_walk($v, 'urldecode');
@array_walk($v, 'addslashes');
}
else
{
$v = addslashes(urldecode($v));
}
$g[$k] = $v;
}
$_GET = $g;
unset($g);
} // www.jb200.com
}
}
public static function getQuery( $key )
{
if( isset( $_GET[$key]) )
{
return self::xss_clean($_GET[$key]);
}
else
{
return false;
}
}

public static function getPost( $key )
{
if( isset( $_POST[$key]) )
{
return self::xss_clean($_POST[$key]);
}
else
{
return false;
}
}
public static function getServer($key)
{
$key = strtoupper($key);
if(isset($_SERVER[$key]))
{
return self::xss_clean($_SERVER[$key]);
}
return false;
}

public static function  getSession( $key )
{
if( isset( $_SESSION[$key]) )
{
return self::xss_clean($_SESSION[$key]);
}
else
{
return false;
}
}
public static function getCookie( $key )
{
if( isset( $_COOKIE[$key]) )
{
return $_COOKIE[$key];
}
else
{
return false;
}
}
/**
 * 过滤非法字符（分发）
 */
private static function xss_clean($str) {
if (is_array($str) && !empty($str)) {
$str = self::xss_clean_arr($str);
} else {
$str = self::xss_clean_str($str);
}
return $str;
}

/**
 * 过滤非法字符(数组)
 */
private static function xss_clean_arr($str) {
foreach ($str as $key => $val) {
if (is_array($val)) {
$val = self::xss_clean_arr($val);
} else {
$val = self::xss_clean_str($val);
}
$arr[$key] = $val;
}
return $arr;
}

/**
 * 过滤非法字符(字符串)
 */
private static function xss_clean_str($str) {
$str = preg_replace('#(alert|cmd|passthru|eval|exec|expression|system|fopen|fsockopen|file|file_get_contents|readfile|unlink)(s*)((.*?))#si', "12&#40;3&#41;", $str);
if (get_magic_quotes_gpc()) {
return $str;
} else {
return addslashes($str);
}
}
}