Navigator operation requested with a context that does not include a Navigator.
The context used to push or pop routes from the Navigator must be that of a widget that is a descendant of a Navigator widget.
这个报错是：因为你尝试使用 Navigator 操作（如 push 或 pop）的 BuildContext 并不在任何 Navigator 的子树中。这意味着你可能在一个没有正确 BuildContext 的地方执行了导航操作。
解决：在MyApp（你的首页）外层再套一个MaterialApp这样就能启用Navigator导航了。
另：如果你要使用Navigator.pushNamed(context, '/image_local_path'); 路由可以注册在这个最顶层的MaterialApp中，代码如下：
void main() {// runApp(const MyApp());//TODO 要外包一个MaterialApp在起始页面,才可以使用Navigator来跳转runApp(//TODO 如果要加路由在这里,就不能用const来修饰// const MaterialApp(MaterialApp(routes: {'/image_local_path': (context) => const ImageLocalPathApp(),'/image_network': (context) => const ImageNetworkApp(),'/input_app_text_filed': (context) => const InputTextFiledApp(),'/input_app_form': (context) => const InputFormApp(),},title: "起始页面",home: const MyApp(),));
}class MyApp extends StatefulWidget {const MyApp({super.key});@override_MyAppState createState() => _MyAppState();
}class _MyAppState extends State<MyApp> {late bool isShowChild;//当widget第一次插入到widget树时会被调用,//对于每次各state对象,flutter framework 只会调用一次@overridevoid initState() {super.initState();isShowChild = true;debugPrint("parent initState......");}//初始化时,在initState()之后立刻调用//当一栏的InheritedWidget rebuild,会出发此方法被调用@overridevoid didChangeDependencies() {super.didChangeDependencies();debugPrint("parent didChangeDependencies......");}//绘制界面,当setState触发的时候会再次被调用@overrideWidget build(BuildContext context) {debugPrint("parent build ......");return MaterialApp(//主页面 Scaffold:Material Design布局结构的基础实现home: Scaffold(appBar: AppBar(title: const Text("Text")),//ScrollView是一个抽象类,所以不能直接用// body: ScrollView(body: SingleChildScrollView(physics: const BouncingScrollPhysics(),child: Column(mainAxisAlignment: MainAxisAlignment.center,crossAxisAlignment: CrossAxisAlignment.center,children: <Widget>[ElevatedButton(onPressed: () {setState(() {isShowChild = !isShowChild;});},child: isShowChild ? const Child() : const Text("演示清除Child"),),const SizedBox(height: 16), // 添加一些间距_textBody(),const Icon(Icons.star, size: 60, color: Colors.amber),const SizedBox(height: 16), // 添加一些间距const Text('Welcome!', style: TextStyle(fontSize: 24)),const SizedBox(height: 16), // 添加一些间距_richTextBody(),_defaultStyle(),flutterLogo(),icon(),Image.asset("assets/payment_black.png"),Image.network("https://www.baidu.com/img/bdlogo.png"),const CircleAvatar(//图片提供者 ImageProviderbackgroundImage: AssetImage("assets/head.jpg"),//半径,控制大小radius: 50.0,),ElevatedButton(onPressed: () {Navigator.pushNamed(context, '/image_local_path');// Navigator.push(// context,// MaterialPageRoute(// builder: (context) => const ImageLocalPathApp()),// );},child: const Text('Go to Second Page'),),],),),),);}//状态改变的时候会调用该方法,比如调用了setState@overridevoid didUpdateWidget(covariant MyApp oldWidget) {super.didUpdateWidget(oldWidget);debugPrint("parent didUpdateWidget......");}//当state对象从树中被移除时,会调用此回调@overridevoid deactivate() {super.deactivate();debugPrint("parent deactivate......");}//当state对象从树中永久移除的时候调用;//通常在此回调中释放资源@overridevoid dispose() {super.dispose();debugPrint("parent dispose......");}
}
)
