您可以使用在此link上共享的相同方法：

final _themeGlobalKey = new GlobalKey(debugLabel: 'app_theme');

class AppTheme extends StatefulWidget {

  final child;

  AppTheme({
    this.child,
  }) : super(key: _themeGlobalKey);

  @override
  AppThemeState createState() => new AppThemeState();
}

class AppThemeState extends State<AppTheme> {

  ThemeData _theme = DEV_THEME;

  set theme(newTheme) {
    if (newTheme != _theme) {
      setState(() => _theme = newTheme);
    }
  }

  @override
  Widget build(BuildContext context) {
    return new ThemeChanger(
      appThemeKey: _themeGlobalKey,
      child: new Theme(
        data: _theme,
        child: widget.child,
      ),
    );
  }
}

class ThemeChanger extends InheritedWidget {

  static ThemeChanger of(BuildContext context) {
    return context.inheritFromWidgetOfExactType(ThemeChanger);
  }

  final ThemeData theme;
  final GlobalKey _appThemeKey;

  ThemeChanger({
    appThemeKey,
    this.theme,
    child
  }) : _appThemeKey = appThemeKey, super(child: child);

  set appTheme(AppThemeOption theme) {
    switch (theme) {
      case AppThemeOption.experimental:
        (_appThemeKey.currentState as AppThemeState)?.theme = EXPERIMENT_THEME;
        break;
      case AppThemeOption.dev:
        (_appThemeKey.currentState as AppThemeState)?.theme = DEV_THEME;
        break;
    }
  }

  @override
  bool updateShouldNotify(ThemeChanger oldWidget) {
    return oldWidget.theme == theme;
  }

}

在要更改主题其他类中

setState(() {
    ThemeChanger.of(context).appTheme = appThemeLight;
  });