Material 模板

pubspec.yaml

把字体复制到fonts目录下，字体从这里下载

flutter:
  uses-material-design: true
  assets:
    - assets/
  fonts:
    - family: "PuHui"
      fonts:
        - asset: fonts/AlibabaPuHuiTi-3-Regular.ttf

main.dart

class MainTranslations extends Translations {
  @override
  Map<String, Map<String, String>> get keys => {
    'en_US': enUS,
    'zh_CN': zhCN,
    'zh_TW': zhTW,
  };
}

class MainApp extends StatefulWidget {
  const MainApp({super.key});

  @override
  State<MainApp> createState() => _MainAppState();
}

class _MainAppState extends State<MainApp> {

  final Controller controller=Get.find();

  @override
  Widget build(BuildContext context) {
    final Brightness brightness = MediaQuery.of(context).platformBrightness;
    controller.darkModeHandler(brightness == Brightness.dark);

    return Obx(()=>
      GetMaterialApp(
        translations: MainTranslations(), 
        debugShowCheckedModeBanner: false,
        localizationsDelegates: [
          GlobalMaterialLocalizations.delegate,
          GlobalWidgetsLocalizations.delegate,
          GlobalCupertinoLocalizations.delegate
        ],
        locale: controller.lang.value.locale, 
        supportedLocales: supportedLocales.map((item)=>item.locale).toList(),
        theme: ThemeData(
          brightness: controller.darkMode.value ? Brightness.dark : Brightness.light,
          fontFamily: 'PuHui', 
          colorScheme: ColorScheme.fromSeed(
            seedColor: Colors.orange,
            brightness: controller.darkMode.value ? Brightness.dark : Brightness.light,
          ),
          textTheme: controller.darkMode.value ? ThemeData.dark().textTheme.apply(
            fontFamily: 'PuHui',
            bodyColor: Colors.white,
            displayColor: Colors.white,
          ) : ThemeData.light().textTheme.apply(
            fontFamily: 'PuHui',
          ),
        ),
        home: MainWindow()
      ),
    );
  }
}

controller.dart

class LanguageType{
  String name;
  Locale locale;

  LanguageType(this.name, this.locale);
}

List<LanguageType> get supportedLocales => [
  LanguageType("English", const Locale("en", "US")),
  LanguageType("简体中文", const Locale("zh", "CN")),
  LanguageType("繁體中文", const Locale("zh", "TW")),
];

class Controller extends GetxController {

  RxBool autoDark=true.obs;
  RxBool darkMode=false.obs;

  Rx<LanguageType> lang=Rx(supportedLocales[0]);

  late SharedPreferences prefs;

  Future<void> initLang() async {
    prefs=await SharedPreferences.getInstance();

    int? langIndex=prefs.getInt("langIndex");

    if(langIndex==null){
      final deviceLocale=PlatformDispatcher.instance.locale;
      final local=Locale(deviceLocale.languageCode, deviceLocale.countryCode);
      int index=supportedLocales.indexWhere((element) => element.locale==local);
      if(index!=-1){
        lang.value=supportedLocales[index];
        lang.refresh();
      }
    }else{
      lang.value=supportedLocales[langIndex];
    }
  }

  void changeLanguage(int index){
    lang.value=supportedLocales[index];
    prefs.setInt("langIndex", index);
    lang.refresh();
    Get.updateLocale(lang.value.locale);
  }

  void darkModeHandler(bool dark){
    if(autoDark.value){
      darkMode.value=dark;
    }
  }
}