/// WidgetsBindingObserver 包含了各种控件的生命周期通知
class _HomePageState extends State<HomePage> with WidgetsBindingObserver {

  ///重写 WidgetsBindingObserver 中的 didChangeAppLifecycleState
  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    ///通过state判断App前后台切换
    if (state == AppLifecycleState.resumed) {

    }
  }

  @override
  Widget build(BuildContext context) {
    return new Container();
  }
}