/**
  * 返回COOKIE中得UUID,如果没有则生成一个并写入COOKIE中
  * @author zeroq
  * @return type
  */
 protected function getUuid()
 {
     if (isset($_COOKIE['uuid'])) {
         $uuid = $_COOKIE['uuid'];
     } else {
         $uuid = CommonHelper::guid();
         $domain = '.' . CommonHelper::getDomain();
         setcookie('uuid', $uuid, time() + 63072000, '/', $domain);
     }
     $this->uuid = $uuid;
     return $uuid;
 }