getAccessToken by memcache

 private function getAccessToken() {

    $memcache_obj = memcache_connect("localhost", 11211);
    $access_token=$memcache_obj->get(‘access_token‘);
    if(!$access_token){
       $url = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=$this->appId&secret=$this->appSecret";
      $res = json_decode($this->httpGet($url));
       $access_token = $res->access_token;
      if ($access_token) {
          $memcache_obj->set(‘access_token‘, $ticket, false, 7000);
      }
    }
    return $access_token;
  }