如果你適配使用的是 ：

flutter_screenutil: ^5.9.3

并且你將 ScreenUtil.init 放在 MyApp 中進(jìn)行初始化，那么恭喜你，遇到了和我一樣的錯誤。
我接手的別人的項目，這個錯誤在debug模式下運(yùn)行沒有問題，當(dāng)打release包后，安卓安裝運(yùn)行發(fā)現(xiàn)頁面空白，布局不顯示，然后調(diào)試，發(fā)現(xiàn)ScreenUtil這個插件適配代碼無效。
原因就是初始化方式錯誤，官方提供了兩種初始化方法：
第一種，ScreenUtilInit：

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    //Set the fit size (Find your UI design, look at the dimensions of the device screen and fill it in,unit in dp)
    return ScreenUtilInit(
      designSize: const Size(360, 690),
      minTextAdapt: true,
      splitScreenMode: true,
      // Use builder only if you need to use library outside ScreenUtilInit context
      builder: (_ , child) {
        return MaterialApp(
          debugShowCheckedModeBanner: false,
          title: 'First Method',
          // You can use the library anywhere in the app even in theme
          theme: ThemeData(
            primarySwatch: Colors.blue,
            textTheme: Typography.englishLike2018.apply(fontSizeFactor: 1.sp),
          ),
          home: child,
        );
      },
      child: const HomePage(title: 'First Method'),
    );
  }
}

第二種，ScreenUtil.init（官方推薦混合開發(fā)使用第二種方法）：

void main() async {
  // Add this line
  await ScreenUtil.ensureScreenSize();
  runApp(MyApp());
}
...
MaterialApp(
  ...
  builder: (ctx, child) {
    ScreenUtil.init(ctx);
    return Theme(
      data: ThemeData(
        primarySwatch: Colors.blue,
        textTheme: TextTheme(bodyText2: TextStyle(fontSize: 30.sp)),
      ),
      child: HomePage(title: 'FlutterScreenUtil Demo'),
    );
  },
)

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'Flutter_ScreenUtil',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: HomePage(title: 'FlutterScreenUtil Demo'),
    );
  }
}

class HomePage extends StatefulWidget {
  const HomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  @override
  Widget build(BuildContext context) {
    //Set the fit size (fill in the screen size of the device in the design) 
    //If the design is based on the size of the 360*690(dp)
    ScreenUtil.init(context, designSize: const Size(360, 690));
    ...
  }
}

ScreenUtil.init這個方法一般放在根路由即第一個頁面加載的時候進(jìn)行初始化， 因為這個時候還沒加載 MaterialApp 無法使用 MediaQuery.of(context ) 獲取到屏幕寬高。