flutter - 如何将根文件(main.dart)中的数据传递到不同的页面，例如在flutter中的android广播接收器

我想定期将数据从main.dart文件传递到当前可见的屏幕。我想在项目中使用哪个 flutter 组件？

最佳答案

您需要使用Stream.periodic功能和Provider软件包。下面是一个简单的例子:

创建一个business logic component

class Bloc {
  /// Stream controller
  final _streamController = StreamController<Object>.broadcast();

  /// Object sink (send objects here)
  void sink(Object value) => _streamController.add(value);

  /// Object stream (listenable for objects)
  Stream<Object> get stream => _streamController.stream;

  void dispose() {
    _streamController.close();
  }
}

这是一个main page包装器(即应用程序):

class MyApp extends StatelessWidget {
  final bloc = Bloc()

  MyApp() {
    // Send object to stream each minute
    Stream.periodic(Duration(minutes: 1), (count) {
      bloc.sink(count);
    });
  }

  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'Some App',
      theme: hemeData(
        primarySwatch: Colors.blue,
      ),
      // Provide `Bloc` object for `MainScreen` widget and its children
      home: Provider<Bloc>(
        create: (_) => bloc, // already created bloc
        dispose: (_, bloc) => bloc.dispose(),  // bloc will be disposed automatically
        child: MainScreen(),
      ),
    );
  }
}

这是一个MainScreen:

class MainScreen extends StatefulWidget {
  /// Bloc to use in this screen
  Bloc bloc;

  @override
  void initState() {
    super.initState();
    // Take `bloc` from widget tree (it is provided via `Provider` above
    bloc = Provider.of<Bloc>(context);
    // Subscribe for listening of objects
    bloc.stream.listen((object) {
      // Do some action when object received
      print('$object');
    });
  }

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