详解Flutter 响应式状态管理框架GetX

#非空安全最后一个版本（flutter 2.0之前版本）
get: ^3.26.0
#空安全版本 
get: ^4.6.5

import 'package:get/get.dart';

void main() => runApp(GetMaterialApp(home: Home()));

class Controller extends GetxController{
  var count = 0.obs;
  increment() => count++;
}

class Home extends StatelessWidget {
  @override
  Widget build(context) {
    final Controller c = Get.put(Controller());
    return Scaffold(
      appBar: AppBar(title: Obx(() => Text("Clicks: ${c.count}"))),
      body: Center(child: ElevatedButton(
              child: Text("Go to Other"), onPressed: () => Get.to(Other()))),
      floatingActionButton:
          FloatingActionButton(child: Icon(Icons.add), onPressed: c.increment));
  }
}
class Other extends StatelessWidget {
  final Controller c = Get.find();
  @override
  Widget build(context){
     return Scaffold(body: Center(child: Text("${c.count}")));
  }
}

GetMaterialApp(  
  home: MyHome(),
)

Get.to(NextScreen());
Get.toNamed('/details');

void main() {
  runApp(
    GetMaterialApp(
      initialRoute: '/',
      getPages: [
        GetPage(name: '/', page: () => MyHomePage()),
        GetPage(name: '/second', page: () => Second()),
        GetPage(
          name: '/third',
          page: () => Third(),
          transition: Transition.zoom  
        ),
      ],
    )
  );
}

Get.back();

Get.off(NextScreen());

Get.offAll(NextScreen());

Controller controller = Get.put(Controller()); 

controller.fetchApi();

Controller controller = Get.find();
Text(controller.textFromApi);

import 'package:get/get.dart';
class Messages extends Translations {
  @override
  Map<String, Map<String, String>> get keys => {
        'en_US': {
          'hello': 'Hello World',
        },
        'de_DE': {
          'hello': 'Hallo Welt',
        }
      };
}

Text('title'.tr);

import 'package:get/get.dart';
Map<String, Map<String, String>> get keys => {
    'en_US': {
        'logged_in': 'logged in as @name with email @email',
    },
    'es_ES': {
       'logged_in': 'iniciado sesión como @name con e-mail @email',
    }
};
Text('logged_in'.trParams({
  'name': 'Jhon',
  'email': 'jhon@example.com'
  }));

return GetMaterialApp(
    translations: Messages(),  
    locale: Locale('en', 'US'),  
    fallbackLocale: Locale('en', 'UK'), 
);

var locale = Locale('en', 'US');
Get.updateLocale(locale);

Get.changeTheme(ThemeData.light());

Get.changeTheme(Get.isDarkMode? ThemeData.light(): ThemeData.dark());

class UserProvider extends GetConnect {
  // Get request
  Future<Response> getUser(int id) => get('http://youapi/users/$id');
  // Post request
  Future<Response> postUser(Map data) => post('http://youapi/users', body: data);
  // Post request with File
  Future<Response<CasesModel>> postCases(List<int> image) {
    final form = FormData({
      'file': MultipartFile(image, filename: 'avatar.png'),
      'otherFile': MultipartFile(image, filename: 'cover.png'),
    });
    return post('http://youapi/users/upload', form);
  }
  GetSocket userMessages() {
    return socket('https://yourapi/users/socket');
  }
}

class HomeProvider extends GetConnect {
  @override
  void onInit() {
    // All request will pass to jsonEncode so CasesModel.fromJson()
    httpClient.defaultDecoder = CasesModel.fromJson;
    httpClient.baseUrl = 'https://api.covid19api.com';
    // baseUrl = 'https://api.covid19api.com'; // It define baseUrl to
    // Http and websockets if used with no [httpClient] instance
    // It's will attach 'apikey' property on header from all requests
    httpClient.addRequestModifier((request) {
      request.headers['apikey'] = '12345678';
      return request;
    });
    // Even if the server sends data from the country "Brazil",
    // it will never be displayed to users, because you remove
    // that data from the response, even before the response is delivered
    httpClient.addResponseModifier<CasesModel>((request, response) {
      CasesModel model = response.body;
      if (model.countries.contains('Brazil')) {
        model.countries.remove('Brazilll');
      }
    });
    httpClient.addAuthenticator((request) async {
      final response = await get("http://yourapi/token");
      final token = response.body['token'];
      // Set the header
      request.headers['Authorization'] = "$token";
      return request;
    });
    //Autenticator will be called 3 times if HttpStatus is
    //HttpStatus.unauthorized
    httpClient.maxAuthRetries = 3;
  }
  }
  @override
  Future<Response<CasesModel>> getCases(String path) => get(path);
}

final middlewares = [
  GetMiddleware(priority: 2),
  GetMiddleware(priority: 5),
  GetMiddleware(priority: 4),
  GetMiddleware(priority: -8),
];

RouteSettings redirect(String route) {
  final authService = Get.find<AuthService>();
  return authService.authed.value ? null : RouteSettings(name: '/login')
}

GetPage onPageCalled(GetPage page) {
  final authService = Get.find<AuthService>();
  return page.copyWith(title: 'Welcome ${authService.UserName}');
}

List<Bindings> onBindingsStart(List<Bindings> bindings) {
  final authService = Get.find<AuthService>();
  if (authService.isAdmin) {
    bindings.add(AdminBinding());
  }
  return bindings;
}

GetPageBuilder onPageBuildStart(GetPageBuilder page) {
  print('bindings are ready');
  return page;
}

MaterialApp(
  navigatorKey: Get.key,
  navigatorObservers: [GetObserver()],
);

MaterialApp(
  navigatorKey: Get.key,
  navigatorObservers: [
    GetObserver(MiddleWare.observer) // Here
  ],
);

GetMaterialApp(
  enableLog: true,
  defaultTransition: Transition.fade,
  opaqueRoute: Get.isOpaqueRouteDefault,
  popGesture: Get.isPopGestureEnable,
  transitionDuration: Get.defaultDurationTransition,
  defaultGlobalState: Get.defaultGlobalState,
);
Get.config(
  enableLog = true,
  defaultPopGesture = true,
  defaultTransition = Transitions.cupertino
)

class Controller extends GetController with StateMixin<User>{}

change(data, status: RxStatus.success());

RxStatus.loading();
RxStatus.success();
RxStatus.empty();
RxStatus.error('message');

class OtherClass extends GetView<Controller> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: controller.obx(
        (state)=>Text(state.name),
        onLoading: CustomLoadingIndicator(),
        onEmpty: Text('No data found'),
        onError: (error)=>Text(error),
      ),
    );
}

Future<void> main() async {
  await initServices();  
  runApp(SomeApp());
}
void initServices() async {
  print('starting services ...');
  await Get.putAsync(() => DbService().init());
  await Get.putAsync(SettingsService()).init();
  print('All services started...');
}
class DbService extends GetxService {
  Future<DbService> init() async {
    print('$runtimeType delays 2 sec');
    await 2.delay();
    print('$runtimeType ready!');
    return this;
  }
}
class SettingsService extends GetxService {
  void init() async {
    print('$runtimeType delays 1 sec');
    await 1.delay();
    print('$runtimeType ready!');
  }
}