/**     * [shell 登陆超时]     * @param  [type] $onlinetime [description]     * @return [type]             [description]     */    function shell($onlinetime){        $newtime=time();        if($newtime-$onlinetime >3000){            if(isset($_SESSION['username']) && isset($_SESSION['uid'])){                unset($_SESSION['username']);                unset($_SESSION['uid']);                $this->error('登录超时!',U('Login/index'));            }        }else{            $_SESSION['time']=time();        }    }