protected function error($msg = '', $url = null, $data = '', $wait = 3){
$this->cache_control();
return parent::error($msg, $url, $data, $wait);
}

protected function cache_control($time = null) {
if (empty($time))
$time = 60 * 60 * 24;
header ("Last-Modified: " .gmdate("D, d M Y H:i:s", time() )." GMT");
header ("Expires: " .gmdate("D, d M Y H:i:s", time() + $time )." GMT");
header ("Cache-Control: max-age=$time");
}


因为我的后台用了iframe，需要控制这个页面为不缓存，要不然Chrome会报错