dart - Flutter 生命周期暂停方法未被调用

Question

当我按下设备上的后退按钮退出应用程序时，我正在使用一个非常简单的代码来检查 Flutter 生命周期回调中 suspending 方法的工作情况。但它没有被调用。

class _HomePageState extends State<HomePage> with WidgetsBindingObserver {
  WidgetsBinding binding = WidgetsBinding.instance;

  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    print("state: $state");
  }

  @override
  void initState() {
    super.initState();
    binding.addObserver(this);
  }

  @override
  Widget build(BuildContext context) {
    return Center(child: Text("Center"));
  }

  @override
  void dispose() {
    binding.removeObserver(this);
    super.dispose();
  }
}

Answer 1

你应该试试 didPopRoute() Android 上后退按钮的生命周期钩子(Hook)。来自文档:

Called when the system tells the app to pop the current route. For example, on Android, this is called when the user presses the back button.

class _HomePageState extends State<HomePage> with WidgetsBindingObserver {
  WidgetsBinding binding = WidgetsBinding.instance;

  @override
  Future<bool> didPopRoute() {
    // Android user pressed back button
    final bool preventAppFromClosing = true;
    return preventAppFromClosing;
  }

  @override
  void initState() {
    super.initState();
    binding.addObserver(this);
  }

  @override
  void dispose() {
    binding.removeObserver(this);
    super.dispose();
  }
}