dart - 如何在 Flutter 应用程序启动时设置数据库？

Question

我想在我的应用程序启动时尽快在屏幕上显示一个小部件。在向用户显示小部件后，我想在通过按下另一个屏幕离开启动屏幕之前进行一些应用程序初始化(例如设置数据库)。我无法弄清楚将我的应用程序初始化代码放在哪里。类似于 iOS 上的 viewDidAppear。

这是我基于initState尝试的。

class Launch extends StatefulWidget {
  @override
  _LaunchState createState() {
    return _LaunchState();
  }
}

class _LaunchState extends State<Launch> {
  @override
  Widget build(final BuildContext context) {
    print('LaunchState build start');
    final Widget w = Center(
      child: Text('Launching...'),
    );
    print('LaunchState build end');
    return w;
  }

  @override
  void initState() {
    print('LaunchState initState start');
    super.initState();
    print('LaunchState initState middle');
    _appInitialization();
    print('LaunchState initState end');
  }

  void _appInitialization() {
    print('LaunchState _appInitialization');
  }

}

输出是

flutter: LaunchState initState start
flutter: LaunchState initState middle
flutter: LaunchState _appInitialization
flutter: LaunchState initState end
flutter: LaunchState build start
flutter: LaunchState build end

我想我想看到的输出是

flutter: LaunchState build start
flutter: LaunchState build end
flutter: LaunchState initState start
flutter: LaunchState initState middle
flutter: LaunchState _appInitialization
flutter: LaunchState initState end

也许我会以一种非常稳健的方式来解决这个问题。如果有完全不同的方法，我会洗耳恭听。

解决方案

感谢 Mangaldeep Pannu 的回答，看来我缺少 async。

class Launch extends StatefulWidget {
  @override
  _LaunchState createState() {
    return _LaunchState();
  }
}

class _LaunchState extends State<Launch> {
  @override
  Widget build(final BuildContext context) {
    print('LaunchState build start');
    final Widget w = Center(
      child: Text('Launching...'),
    );
    print('LaunchState build end');
    return w;
  }

  @override
  void initState() {
    print('LaunchState initState start');
    super.initState();
    print('LaunchState initState middle');
    _appInitialization(); // no await
    print('LaunchState initState end');
  }

  void _appInitialization() async {
    print('LaunchState _appInitialization begin');
    // simulate some time consuming initialization task
    await Future.delayed(Duration(seconds: 5));
    print('LaunchState _appInitialization middle');
    Navigator.push(...);
    print('LaunchState _appInitialization end');
  }

}

结果是

flutter: LaunchState initState start
flutter: LaunchState initState middle
flutter: LaunchState _appInitialization begin
flutter: LaunchState initState end
flutter: LaunchState build start
flutter: LaunchState build end
[5 second pause]
flutter: LaunchState _appInitialization middle
flutter: LaunchState _appInitialization end

Answer 1

在应用启动时打开的第一个小部件中

@override
void initState() {
  onStart();
}

void onStart() async {
  await loadData();  //load your data here
  Navigator.push();  //push to next screen
}

onStart 将加载数据异步。
当数据加载时推送到下一个屏幕。