PHP 防止恶意用户快速刷新页面

<?php/** * 防止快速刷新 * */session_start();header("Content-type:text/html;charset=utf-8");error_reporting(E_ALL^E_NOTICE);// 参数: N秒内刷新M次,就禁止访问! 并且关小黑屋X秒!$seconds = 3; //时间段[秒]$refresh = 20; //刷新次数$disdeny = 10; // 放开限制的时间: 30秒后$sid = session_id();if( !$_SESSION['denyvisitor'] ){    $_SESSION['denyvisitor']=array();}if( in_array($sid,$_SESSION['denyvisitor']) && ( time()-$_SESSION['denytimestamp'][$sid]<$disdeny ) ){    $alsotime = $disdeny - ( time()-$_SESSION['denytimestamp'][$sid] );    exit( "您被关到小黑屋了! <span style='color:#f00;font-size:22px;'>{$alsotime}</span> 秒后可获自由!" );}empty($_SERVER['HTTP_VIA']) or exit('Access Denied'); //代理IP直接退出//设置监控变量$cur_time = time();if(isset($_SESSION['last_time'])){    $_SESSION['refresh_times'] += 1;}else{    $_SESSION['refresh_times'] = 1;    $_SESSION['last_time'] = $cur_time;}//处理监控结果if($cur_time - $_SESSION['last_time'] < $seconds){    if($_SESSION['refresh_times'] >= $refresh){        if(!in_array($$sid,$_SESSION['denyvisitor'])){            $_SESSION['denyvisitor'][] = $sid;            $_SESSION['denytimestamp'][$sid] = time();        }    }}else{    $_SESSION['refresh_times'] = 0;    $_SESSION['last_time'] = $cur_time;}