flutter - MaterialApp 中的主题在小部件 Flutter 中不起作用

Question

这是我的代码，我明确定义了主题，如下所示。
但是，home 中容器的颜色在 Chrome 浏览器中仍然是蓝色的。

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Spotify UI',
      debugShowCheckedModeBanner: false,
      themeMode: ThemeMode.dark,
      darkTheme: ThemeData(
        brightness: Brightness.dark,
        appBarTheme: const AppBarTheme(backgroundColor: Colors.black),
        scaffoldBackgroundColor: const Color(0xFF121212),
        backgroundColor: const Color(0xFF121212),
        primaryColor: Colors.black,
        accentColor: const Color(0xFF1DB954),
        iconTheme: const IconThemeData().copyWith(color: Colors.white),
        fontFamily: 'Montserrat',
        textTheme: TextTheme(
          headline2: const TextStyle(
            color: Colors.white,
            fontSize: 32.0,
            fontWeight: FontWeight.bold,
          ),
          headline4: TextStyle(
            fontSize: 12.0,
            color: Colors.grey[300],
            fontWeight: FontWeight.w500,
            letterSpacing: 2.0,
          ),
          bodyText1: TextStyle(
            color: Colors.grey[300],
            fontSize: 14.0,
            fontWeight: FontWeight.w600,
            letterSpacing: 1.0,
          ),
          bodyText2: TextStyle(
            color: Colors.grey[300],
            letterSpacing: 1.0,
          ),
        ),
      ),
      home: Column(
        children: [
          Expanded(
            child: Container(
              color: Theme.of(context).primaryColor,
            ),
          )
        ],
      ),
    );
  }
}

Answer 1

这是因为您的 Container 的颜色小部件取自 context ，这是 build 的一个参数MyApp的方法.MaterialApp有一个主题，但 MyApp没有主题。所以当你使用 context的 MyApp要获得原色，该上下文还没有任何主题，您将获得默认的原色。
相反，您可以做的是:

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Spotify UI',
      debugShowCheckedModeBanner: false,
      themeMode: ThemeMode.dark,
      darkTheme: ThemeData(
        // ...
      ),
      home: MyWidget(),
    );
  }
}

class MyWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        Expanded(
          child: Container(
            color: Theme.of(context).primaryColor,
          ),
        )
      ],
    );
  }
}