Flutter 如何在Flatter中的共享首选项中存储主题

在这里，我有一个屏幕，我有一些按钮，当我按下按钮时，它将改变应用程序的颜色，但当我重新启动应用程序时，它将重置。我希望它不会重置，直到我改变了应用程序的颜色。因此，我想在共享首选项中存储主题数据，并从共享首选项中获取主题数据，因此每当我重新启动应用程序时，它都需要从共享首选项中获取主题

这是我试过的一些代码

MEBLOCK.dart

class ThemeBloc extends Bloc<ThemeEvent, ThemeState> {
  @override
  ThemeState get initialState =>
      ThemeState(themeData: appThemeData[AppTheme.GreenLight]);

  @override
  Stream<ThemeState> mapEventToState(
    ThemeEvent event,
  ) async* {
    if (event is ThemeChanged) {
      yield ThemeState(themeData: appThemeData[event.theme]);
    }
  }
}

abstract class ThemeEvent extends Equatable {
  ThemeEvent([List props = const <dynamic>[]]) : super(props);
}

class ThemeChanged extends ThemeEvent {
  final AppTheme theme;

  ThemeChanged({
    this.theme,
  }) : super([theme]);
}

@immutable
class ThemeState extends Equatable {
  final ThemeData themeData;

  ThemeState({
    @required this.themeData,
  }) : super([themeData]);
}

enum AppTheme {
  GreenLight,
  GreenDark,
  BlueLight,
  BlueGrey,
  Amber,
}

final appThemeData = {
  AppTheme.GreenLight: ThemeData(
    brightness: Brightness.light,
    primaryColor: Colors.teal,
  ),
  AppTheme.GreenDark: ThemeData(
    brightness: Brightness.light,
    primaryColor: Colors.orange,
  ),
};

AppTheme.dart

class ThemeBloc extends Bloc<ThemeEvent, ThemeState> {
  @override
  ThemeState get initialState =>
      ThemeState(themeData: appThemeData[AppTheme.GreenLight]);

  @override
  Stream<ThemeState> mapEventToState(
    ThemeEvent event,
  ) async* {
    if (event is ThemeChanged) {
      yield ThemeState(themeData: appThemeData[event.theme]);
    }
  }
}

abstract class ThemeEvent extends Equatable {
  ThemeEvent([List props = const <dynamic>[]]) : super(props);
}

class ThemeChanged extends ThemeEvent {
  final AppTheme theme;

  ThemeChanged({
    this.theme,
  }) : super([theme]);
}

@immutable
class ThemeState extends Equatable {
  final ThemeData themeData;

  ThemeState({
    @required this.themeData,
  }) : super([themeData]);
}

enum AppTheme {
  GreenLight,
  GreenDark,
  BlueLight,
  BlueGrey,
  Amber,
}

final appThemeData = {
  AppTheme.GreenLight: ThemeData(
    brightness: Brightness.light,
    primaryColor: Colors.teal,
  ),
  AppTheme.GreenDark: ThemeData(
    brightness: Brightness.light,
    primaryColor: Colors.orange,
  ),
};

---

您可以简单地保存/检索一个主题id，该id可用于识别启动应用程序时选择的主题，如

class ThemeBloc extends Bloc<ThemeEvent, ThemeState> {

  // at this point you should be already have a mainSharedPreferences already initialized, could be in SplashScreen
  // to prevent async calls in the initialState

  @override
  ThemeState get initialState => ThemeState(
      themeData: appThemeData[
          MyApp.mainSharedPreferences.getInt("selectedThemeIndex") ??
              AppTheme.GreenLight]);

  @override
  Stream<ThemeState> mapEventToState(
    ThemeEvent event,
  ) async* {
    if (event is ThemeChanged) {
      await _persistTheme(event.theme);
      yield ThemeState(themeData: appThemeData[event.theme]);
    }
  }

  _persistTheme(AppTheme theme) async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    prefs.setInt("selectedThemeIndex", theme.index);
    // or you could save the theme.toString()
    // prefs.setString("selectedTheme", theme.toString());
  }
}

---

您可以将其序列化/反序列化为JSONA，我如何存储主题id？？从哪里我可以得到主题ID？你可以定义你自己的主题ID，例如ID:1=>theme1，等等@RutvikGumasana我编辑了我的答案，这可以让你开始谢谢你这么多我会尝试代码，让你知道：）@SlahLayouni嗨，我有一个关于你的解决方案的问题。如何同步加载SharedReference？我也有同样的问题，我想从SharedReferences加载语言和主题，并将其保存在initialState中。谢谢！