Flutter监听前后台切换事件

class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> with WidgetsBindingObserver {
	@override
  void initState() {
    WidgetsBinding.instance.addObserver(this);
  }
  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    print("-didChangeAppLifecycleState-" + state.toString());
    switch (state) {
      case AppLifecycleState.inactive: // 处于这种状态的应用程序应该假设它们可能在任何时候暂停。
        break;
      case AppLifecycleState.resumed: //从后台切换前台，界面可见
        break;
      case AppLifecycleState.paused: // 界面不可见，后台
        break;
      case AppLifecycleState.detached: // APP结束时调用
        break;
    }
  }
   @override
  void dispose() {
    WidgetsBinding.instance.removeObserver(this);
    super.dispose();
  }
}