已编辑

您必须在MediaQuery的上下文之上提供它：

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: BaseLayout()
    );
  }
}

class BaseLayout extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Container(
          height: MediaQuery.of(context).size.height,
          color: Colors.red,
        ),
      ),
    );
  }
}

创建一个自己类，您的错误就应该消失了。

原始答案

您的部件树中是否有MaterialApp？MaterialApp提供MediaQuery。

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      body:WhateverWidget
    );
  }
}

顺便说一句...解决方案在您的错误代码中;）

This can happen because you have not added a WidgetsApp, CupertinoApp, or MaterialApp widget (those widgets introduce a MediaQuery), or it can happen if the context you use comes from a widget above those widgets.)

我找到了你的问题的答案，你需要为它添加safeArea

class BaseLayout extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: SafeArea(
        child: Scaffold(
          body: Container(
            height: MediaQuery.of(context).size.height,
            color: Colors.red,
          ),
        ),
      ),
    );
  }
}