综合练习：做一个完整的天气 App

这一课你将能做到

1. 把前 11 课的知识串起来：环境 → Dart → Widget → 状态 → 动画 → 网络 → 存储 → 测试 → 发布
2. 从零搭建一个真实可发布的天气 App，包含城市搜索、当前天气、未来预报、收藏城市
3. 走完「开发 → 测试 → 打包 → 上传 Firebase App Distribution」的完整流程

为什么要学

知识不串起来就是散沙。本课用一个真实复杂度的项目，把所有单点技能连成线。

人话：前 11 课教你做菜的各种刀工火候，这一课让你做一桌完整的宴席。

先建立图像

┌────────────────────────────────────────┐
│  WeatherApp                            │
├────────────────────────────────────────┤
│  UI 层 (Widget)                        │
│    ├── HomePage (当前天气 + 预报)      │
│    ├── SearchPage (搜索城市)           │
│    └── FavoritePage (收藏)             │
├────────────────────────────────────────┤
│  状态层 (Riverpod)                     │
│    ├── weatherProvider                 │
│    ├── favoritesProvider               │
│    └── searchProvider                  │
├────────────────────────────────────────┤
│  数据层                                │
│    ├── WeatherRepository (API)         │
│    └── LocalStorage (SharedPreferences)│
└────────────────────────────────────────┘

跟着做

步骤 1：初始化项目

flutter create weather_app
cd weather_app

pubspec.yaml：

name: weather_app
description: A weather app.
publish_to: 'none'
version: 1.0.0+1

environment:
  sdk: ^3.5.0

dependencies:
  flutter:
    sdk: flutter
  flutter_riverpod: ^2.5.0
  dio: ^5.4.0
  shared_preferences: ^2.2.0
  intl: ^0.19.0
  json_annotation: ^4.9.0

dev_dependencies:
  flutter_test:
    sdk: flutter
  flutter_lints: ^4.0.0
  mocktail: ^1.0.0

flutter:
  uses-material-design: true

步骤 2：定义数据模型

lib/models/weather.dart：

class Weather {
  final String city;
  final double temperature;
  final String description;
  final int humidity;
  final double windSpeed;
  final List<Forecast> forecast;

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

  factory Weather.fromJson(Map<String, dynamic> json) => Weather(
        city: json['name'] as String,
        temperature: (json['main']['temp'] as num).toDouble(),
        description: json['weather'][0]['description'] as String,
        humidity: json['main']['humidity'] as int,
        windSpeed: (json['wind']['speed'] as num).toDouble(),
        forecast: [],
      );
}

class Forecast {
  final DateTime date;
  final double high;
  final double low;
  final String description;

  Forecast({required this.date, required this.high, required this.low, required this.description});
}