尝试用BlocProvider实现颤振应用程序的国际化

import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:flutter_localizations/flutter_localizations.dart';
import 'package:intl/intl.dart';
import 'package:flutter_gen/gen_l10n/app_localizations.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return BlocProvider(
      create: (context) => MyBloc(),
      child: MaterialApp(
        localizationsDelegates: [
          AppLocalizations.delegate,
          GlobalMaterialLocalizations.delegate,
          GlobalWidgetsLocalizations.delegate,
        ],
        supportedLocales: [
          Locale('en', 'US'),
          Locale('zh', 'CN'),
        ],
        onGenerateTitle: (BuildContext context) =>
            AppLocalizations.of(context).appTitle,
        home: MyHomePage(),
      ),
    );
  }
}

class MyHomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(AppLocalizations.of(context).appTitle),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Text(
              AppLocalizations.of(context).greetingMessage,
              style: TextStyle(fontSize: 24),
            ),
            SizedBox(height: 20),
            ElevatedButton(
              onPressed: () {
                BlocProvider.of<MyBloc>(context).changeLanguage();
              },
              child: Text(AppLocalizations.of(context).changeLanguageButton),
            ),
          ],
        ),
      ),
    );
  }
}

class MyBloc extends Bloc<dynamic, Locale> {
  MyBloc() : super(Locale('en', 'US'));

  @override
  Stream<Locale> mapEventToState(dynamic event) async* {
    if (event is ChangeLanguageEvent) {
      if (state.languageCode == 'en') {
        yield Locale('zh', 'CN');
      } else {
        yield Locale('en', 'US');
      }
    }
  }

  void changeLanguage() {
    add(ChangeLanguageEvent());
  }
}

class ChangeLanguageEvent {}