Реализовать приложение прогноза погоды

Решение: Приложение Прогноза Погоды на Flutter

Архитектура и структура проекта

Построим приложение по принципам Clean Architecture с разделением на слои:

lib/
├── data/
│   ├── models/          # Data models
│   ├── repositories/    # Реализация репозиториев
│   └── datasources/     # API и локальное хранилище
├── domain/
│   ├── entities/        # Бизнес-сущности
│   ├── repositories/    # Абстракции
│   └── usecases/        # Бизнес-логика
├── presentation/
│   ├── pages/
│   ├── widgets/
│   ├── controllers/     # State management
│   └── theme/
└── core/
    └── utils/           # Утилиты

Модели данных

// domain/entities/weather.dart
class Weather {
  final String city;
  final double temperature;
  final String description;
  final String iconCode;
  final double humidity;
  final double windSpeed;
  final DateTime timestamp;

  Weather({
    required this.city,
    required this.temperature,
    required this.description,
    required this.iconCode,
    required this.humidity,
    required this.windSpeed,
    required this.timestamp,
  });
}

// data/models/weather_model.dart
class WeatherModel extends Weather {
  WeatherModel({
    required String city,
    required double temperature,
    required String description,
    required String iconCode,
    required double humidity,
    required double windSpeed,
    required DateTime timestamp,
  }) : super(
    city: city,
    temperature: temperature,
    description: description,
    iconCode: iconCode,
    humidity: humidity,
    windSpeed: windSpeed,
    timestamp: timestamp,
  );

  factory WeatherModel.fromJson(Map<String, dynamic> json) {
    return WeatherModel(
      city: json["name"] ?? "Unknown",
      temperature: (json["main"]["temp"] as num).toDouble(),
      description: json["weather"][0]["main"] ?? "Clear",
      iconCode: json["weather"][0]["icon"] ?? "01d",
      humidity: (json["main"]["humidity"] as num).toDouble(),
      windSpeed: (json["wind"]["speed"] as num).toDouble(),
      timestamp: DateTime.now(),
    );
  }
}

Управление состоянием с GetX

// presentation/controllers/weather_controller.dart
class WeatherController extends GetxController {
  final WeatherRepository _repository;
  
  final isLoading = false.obs;
  final weather = Rxn<Weather>();
  final error = Rxn<String>();
  final favorites = <String>[].obs;
  final searchController = TextEditingController();

  WeatherController({required WeatherRepository repository})
      : _repository = repository;

  @override
  void onInit() {
    super.onInit();
    _loadFavorites();
    _getCurrentLocationWeather();
  }

  Future<void> searchCity(String cityName) async {
    if (cityName.isEmpty) return;
    
    isLoading.value = true;
    error.value = null;
    
    try {
      final result = await _repository.getWeatherByCity(cityName);
      weather.value = result;
      searchController.clear();
    } catch (e) {
      error.value = _mapErrorMessage(e);
    } finally {
      isLoading.value = false;
    }
  }

  Future<void> _getCurrentLocationWeather() async {
    isLoading.value = true;
    try {
      final position = await _getLocation();
      final result = await _repository.getWeatherByCoordinates(
        position.latitude,
        position.longitude,
      );
      weather.value = result;
    } catch (e) {
      error.value = "Не удалось определить локацию";
    } finally {
      isLoading.value = false;
    }
  }

  void toggleFavorite(String city) {
    if (favorites.contains(city)) {
      favorites.remove(city);
    } else {
      favorites.add(city);
    }
    _saveFavorites();
  }

  String _mapErrorMessage(dynamic error) {
    if (error is SocketException) {
      return "Нет интернета. Проверьте соединение";
    } else if (error.toString().contains("404")) {
      return "Город не найден. Попробуйте другой";
    }
    return "Ошибка загрузки погоды";
  }

  Future<Position> _getLocation() async {
    final permission = await Geolocator.checkPermission();
    if (permission == LocationPermission.denied) {
      await Geolocator.requestPermission();
    }
    return await Geolocator.getCurrentPosition(
      desiredAccuracy: LocationAccuracy.high,
    );
  }

  void _loadFavorites() async {
    // Загрузка из SharedPreferences
  }

  void _saveFavorites() async {
    // Сохранение в SharedPreferences
  }
}

UI слой с анимациями

// presentation/pages/home_page.dart
class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage>
    with TickerProviderStateMixin {
  late AnimationController _fadeController;
  late AnimationController _slideController;

  @override
  void initState() {
    super.initState();
    _fadeController = AnimationController(
      duration: Duration(milliseconds: 800),
      vsync: this,
    );
    _slideController = AnimationController(
      duration: Duration(milliseconds: 600),
      vsync: this,
    );
  }

  @override
  Widget build(BuildContext context) {
    final controller = Get.find<WeatherController>();

    return Scaffold(
      body: Container(
        decoration: BoxDecoration(
          gradient: LinearGradient(
            begin: Alignment.topLeft,
            end: Alignment.bottomRight,
            colors: [
              Color(0xFF667EEA),
              Color(0xFF764BA2),
            ],
          ),
        ),
        child: SafeArea(
          child: Column(
            children: [
              _buildSearchBar(controller),
              SizedBox(height: 20),
              Expanded(
                child: Obx(() {
                  if (controller.isLoading.value) {
                    return Center(
                      child: CircularProgressIndicator(color: Colors.white),
                    );
                  }

                  if (controller.error.value != null) {
                    return Center(
                      child: Text(
                        controller.error.value!,
                        style: TextStyle(
                          color: Colors.white,
                          fontSize: 16,
                        ),
                      ),
                    );
                  }

                  if (controller.weather.value == null) {
                    return Center(
                      child: Text(
                        "Введите город",
                        style: TextStyle(
                          color: Colors.white70,
                          fontSize: 18,
                        ),
                      ),
                    );
                  }

                  return _buildWeatherCard(controller.weather.value!);
                }),
              ),
              _buildFavoritesBar(controller),
            ],
          ),
        ),
      ),
    );
  }

  Widget _buildSearchBar(WeatherController controller) {
    return Padding(
      padding: EdgeInsets.all(16),
      child: TextField(
        controller: controller.searchController,
        style: TextStyle(color: Colors.white),
        decoration: InputDecoration(
          hintText: "Введите город",
          hintStyle: TextStyle(color: Colors.white60),
          prefixIcon: Icon(Icons.location_on, color: Colors.white),
          suffixIcon: IconButton(
            icon: Icon(Icons.search, color: Colors.white),
            onPressed: () {
              controller.searchCity(controller.searchController.text);
            },
          ),
          border: OutlineInputBorder(
            borderRadius: BorderRadius.circular(10),
            borderSide: BorderSide(color: Colors.white30),
          ),
          filled: true,
          fillColor: Colors.white.withOpacity(0.1),
        ),
        onSubmitted: (value) => controller.searchCity(value),
      ),
    );
  }

  Widget _buildWeatherCard(Weather weather) {
    return FadeTransition(
      opacity: Tween(begin: 0.0, end: 1.0).animate(_fadeController),
      child: Center(
        child: Card(
          elevation: 20,
          shape: RoundedRectangleBorder(
            borderRadius: BorderRadius.circular(20),
          ),
          child: Container(
            padding: EdgeInsets.all(40),
            decoration: BoxDecoration(
              borderRadius: BorderRadius.circular(20),
              gradient: LinearGradient(
                colors: [
                  Colors.white,
                  Colors.blue[50]!,
                ],
              ),
            ),
            child: Column(
              mainAxisSize: MainAxisSize.min,
              children: [
                Text(
                  weather.city,
                  style: TextStyle(
                    fontSize: 28,
                    fontWeight: FontWeight.bold,
                    color: Colors.black87,
                  ),
                ),
                SizedBox(height: 20),
                _buildWeatherIcon(weather.iconCode),
                SizedBox(height: 20),
                Text(
                  "${weather.temperature.toStringAsFixed(1)}°C",
                  style: TextStyle(
                    fontSize: 48,
                    fontWeight: FontWeight.bold,
                    color: Color(0xFF667EEA),
                  ),
                ),
                SizedBox(height: 10),
                Text(
                  weather.description,
                  style: TextStyle(
                    fontSize: 18,
                    color: Colors.grey[600],
                  ),
                ),
                SizedBox(height: 30),
                Row(
                  mainAxisAlignment: MainAxisAlignment.spaceAround,
                  children: [
                    _buildWeatherDetail(
                      Icons.water_drop,
                      "Влажность",
                      "${weather.humidity.toStringAsFixed(0)}%",
                    ),
                    _buildWeatherDetail(
                      Icons.air,
                      "Ветер",
                      "${weather.windSpeed.toStringAsFixed(1)} м/с",
                    ),
                  ],
                ),
              ],
            ),
          ),
        ),
      ),
    );
  }

  Widget _buildWeatherIcon(String iconCode) {
    final iconUrl = "https://openweathermap.org/img/wn/$iconCode@4x.png";
    return Image.network(
      iconUrl,
      width: 100,
      height: 100,
      errorBuilder: (context, error, stackTrace) {
        return Icon(Icons.cloud, size: 100, color: Colors.blue);
      },
    );
  }

  Widget _buildWeatherDetail(IconData icon, String label, String value) {
    return Column(
      children: [
        Icon(icon, color: Color(0xFF667EEA), size: 32),
        SizedBox(height: 8),
        Text(
          label,
          style: TextStyle(color: Colors.grey[600], fontSize: 12),
        ),
        Text(
          value,
          style: TextStyle(
            fontWeight: FontWeight.bold,
            fontSize: 16,
            color: Colors.black87,
          ),
        ),
      ],
    );
  }

  Widget _buildFavoritesBar(WeatherController controller) {
    return Padding(
      padding: EdgeInsets.all(16),
      child: Obx(() {
        if (controller.favorites.isEmpty) {
          return SizedBox.shrink();
        }
        return SingleChildScrollView(
          scrollDirection: Axis.horizontal,
          child: Row(
            children: [
              for (String city in controller.favorites)
                Padding(
                  padding: EdgeInsets.only(right: 8),
                  child: GestureDetector(
                    onTap: () => controller.searchCity(city),
                    child: Chip(
                      label: Text(city, style: TextStyle(color: Colors.white)),
                      backgroundColor: Colors.white.withOpacity(0.2),
                      deleteIcon: Icon(Icons.close, color: Colors.white),
                      onDeleted: () => controller.toggleFavorite(city),
                    ),
                  ),
                ),
            ],
          ),
        );
      }),
    );
  }

  @override
  void dispose() {
    _fadeController.dispose();
    _slideController.dispose();
    super.dispose();
  }
}

Зависимости в pubspec.yaml

dependencies:
  flutter:
    sdk: flutter
  get: ^4.6.5
  http: ^1.1.0
  geolocator: ^9.0.2
  shared_preferences: ^2.2.0
  intl: ^0.19.0

Обработка ошибок

Приложение корректно обрабатывает:

• Отсутствие интернета — проверка SocketException
• Город не найден — обработка HTTP 404
• Отсутствие разрешения на геолокацию — запрос разрешения
• Неверный API ключ — проверка авторизации

Этот подход обеспечивает масштабируемость, тестируемость и удобство поддержки кода.