php中过滤非法字符的具体实现

<?php 
class sqlsafe { 
private $getfilter = "'|(and|or)\\b.+?(>|<|=|in|like)|\\/\\*.+?\\*\\/|<\\s*script\\b|\\bEXEC\\b|UNION.+?SELECT|UPDATE.+?SET|INSERT\\s+INTO.+?VALUES|(SELECT|DELETE).+?FROM|(CREATE|ALTER|DROP|TRUNCATE)\\s+(TABLE|DATABASE)"; 
private $postfilter = "\\b(and|or)\\b.{1,6}?(=|>|<|\\bin\\b|\\blike\\b)|\\/\\*.+?\\*\\/|<\\s*script\\b|\\bEXEC\\b|UNION.+?SELECT|UPDATE.+?SET|INSERT\\s+INTO.+?VALUES|(SELECT|DELETE).+?FROM|(CREATE|ALTER|DROP|TRUNCATE)\\s+(TABLE|DATABASE)"; 
private $cookiefilter = "\\b(and|or)\\b.{1,6}?(=|>|<|\\bin\\b|\\blike\\b)|\\/\\*.+?\\*\\/|<\\s*script\\b|\\bEXEC\\b|UNION.+?SELECT|UPDATE.+?SET|INSERT\\s+INTO.+?VALUES|(SELECT|DELETE).+?FROM|(CREATE|ALTER|DROP|TRUNCATE)\\s+(TABLE|DATABASE)"; 
/** 
* 构造函数 
*/ 
public function __construct() { 
foreach($_GET as $key=>$value){$this->stopattack($key,$value,$this->getfilter);} 
foreach($_POST as $key=>$value){$this->stopattack($key,$value,$this->postfilter);} 
foreach($_COOKIE as $key=>$value){$this->stopattack($key,$value,$this->cookiefilter);} 
} 
/** 
* 参数检查并写日志 
*/ 
public function stopattack($StrFiltKey, $StrFiltValue, $ArrFiltReq){ 
if(is_array($StrFiltValue))$StrFiltValue = implode($StrFiltValue); 
if (preg_match("/".$ArrFiltReq."/is",$StrFiltValue) == 1){ 
$this->writeslog($_SERVER["REMOTE_ADDR"]." ".strftime("%Y-%m-%d %H:%M:%S")." ".$_SERVER["PHP_SELF"]." ".$_SERVER["REQUEST_METHOD"]." ".$StrFiltKey." ".$StrFiltValue); 
showmsg('您提交的参数非法,系统已记录您的本次操作！','',0,1); 
} 
} 
/** 
* SQL注入日志 
*/ 
public function writeslog($log){ 
$log_path = CACHE_PATH.'logs'.DIRECTORY_SEPARATOR.'sql_log.txt'; 
$ts = fopen($log_path,"a+"); 
fputs($ts,$log."\r\n"); 
fclose($ts); 
} 
} 
?>