flutter_theme_manager2 是一个用于管理 Flutter 应用主题的插件。它允许你动态地切换应用的主题，支持亮色和暗色模式，并且可以自定义主题。以下是如何使用 flutter_theme_manager2 的基本步骤：

1. 添加依赖

首先，你需要在 pubspec.yaml 文件中添加 flutter_theme_manager2 依赖：

dependencies:
  flutter:
    sdk: flutter
  flutter_theme_manager2: ^1.0.0

然后运行 flutter pub get 来安装依赖。

2. 初始化主题管理器

在你的 main.dart 文件中，初始化 ThemeManager 并设置默认主题：

import 'package:flutter/material.dart';
import 'package:flutter_theme_manager2/flutter_theme_manager2.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  [@override](/user/override)
  Widget build(BuildContext context) {
    return ThemeManager(
      defaultTheme: ThemeData.light(), // 默认亮色主题
      child: MaterialApp(
        title: 'Flutter Theme Manager Demo',
        theme: ThemeManager.of(context).theme, // 使用 ThemeManager 管理的主题
        home: MyHomePage(),
      ),
    );
  }
}

3. 创建主题切换界面

在你的 MyHomePage 中，你可以创建一个按钮来切换主题：

class MyHomePage extends StatelessWidget {
  [@override](/user/override)
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Theme Manager Demo'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              'Current Theme:',
              style: Theme.of(context).textTheme.headline4,
            ),
            ElevatedButton(
              onPressed: () {
                // 切换主题
                ThemeManager.of(context).toggleTheme();
              },
              child: Text('Toggle Theme'),
            ),
          ],
        ),
      ),
    );
  }
}

4. 自定义主题

你可以通过 ThemeManager 设置自定义主题。例如，你可以在 main.dart 中定义多个主题，并在需要时切换它们：

final ThemeData customLightTheme = ThemeData(
  primarySwatch: Colors.blue,
  brightness: Brightness.light,
);

final ThemeData customDarkTheme = ThemeData(
  primarySwatch: Colors.red,
  brightness: Brightness.dark,
);

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  [@override](/user/override)
  Widget build(BuildContext context) {
    return ThemeManager(
      defaultTheme: customLightTheme, // 默认自定义亮色主题
      child: MaterialApp(
        title: 'Flutter Theme Manager Demo',
        theme: ThemeManager.of(context).theme,
        home: MyHomePage(),
      ),
    );
  }
}

然后在 MyHomePage 中，你可以通过 ThemeManager.of(context).setTheme() 方法来切换自定义主题：

ElevatedButton(
  onPressed: () {
    ThemeManager.of(context).setTheme(customDarkTheme);
  },
  child: Text('Set Dark Theme'),
),
ElevatedButton(
  onPressed: () {
    ThemeManager.of(context).setTheme(customLightTheme);
  },
  child: Text('Set Light Theme'),
),

5. 持久化主题

如果你希望在应用重启后保持用户选择的主题，你可以使用 SharedPreferences 来持久化主题设置。以下是一个简单的示例：

import 'package:shared_preferences/shared_preferences.dart';

class ThemeManager {
  static const String _themeKey = 'theme';

  ThemeData _theme;
  final SharedPreferences _prefs;

  ThemeManager(this._theme, this._prefs);

  ThemeData get theme => _theme;

  void setTheme(ThemeData theme) {
    _theme = theme;
    _prefs.setString(_themeKey, theme == customLightTheme ? 'light' : 'dark');
  }

  void toggleTheme() {
    _theme = _theme == customLightTheme ? customDarkTheme : customLightTheme;
    _prefs.setString(_themeKey, _theme == customLightTheme ? 'light' : 'dark');
  }

  static Future<ThemeManager> load() async {
    final prefs = await SharedPreferences.getInstance();
    final theme = prefs.getString(_themeKey) == 'dark' ? customDarkTheme : customLightTheme;
    return ThemeManager(theme, prefs);
  }
}

然后在 main.dart 中，你可以异步加载主题：

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  final themeManager = await ThemeManager.load();
  runApp(MyApp(themeManager: themeManager));
}

class MyApp extends StatelessWidget {
  final ThemeManager themeManager;

  MyApp({required this.themeManager});

  [@override](/user/override)
  Widget build(BuildContext context) {
    return ThemeManager(
      defaultTheme: themeManager.theme,
      child: MaterialApp(
        title: 'Flutter Theme Manager Demo',
        theme: ThemeManager.of(context).theme,
        home: MyHomePage(),
      ),
    );
  }
}