public static function getSiteUserAgent() { list($key, $ua) = array('_ac_app_ua', ''); if (!$_COOKIE || !isset($_COOKIE[$key]) || !$_COOKIE[$key]) { $ua = substr(md5($_SERVER['HTTP_USER_AGENT'] . '\\t' . rand(1000, 9999) . '\\t' . time()), 8, 18); setcookie($key, $ua, time() + 86400 * 365 * 5); } $ua = $ua ? $ua : $_COOKIE[$key]; return strlen($ua) == 18 ? ACloudSysCoreS::escapeChar($ua) : ''; }