php 后端刷新页面

  public function index()
    {
        $b = date('Y-m-d H:i:s');

        header('refresh:10');
        $c = strtotime($b);
        $d = strtotime('2019-02-15 16:34:00');
        if($c > $d){
            header('Location: http://www.baidu.com');
        }

        return $b;
    }