rice/lib/main.dart

/*
//导入cupertino  widget 库
import 'package:flutter/cupertino.dart';

void main() {
  runApp(const CupertinoTestRoute());
}

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

  @override
  Widget build(BuildContext context) {
    return CupertinoPageScaffold(
      navigationBar: const CupertinoNavigationBar(
        middle: Text("Cupertino Demo"),
      ),
      child: Center(
        child: CupertinoButton(
            color: CupertinoColors.activeBlue,
            child: const Text("Press"),
            onPressed: () {}
        ),
      ),
    );
  }
}
*/

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

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

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        // This is the theme of your application.
        //
        // TRY THIS: Try running your application with "flutter run". You'll see
        // the application has a blue toolbar. Then, without quitting the app,
        // try changing the seedColor in the colorScheme below to Colors.green
        // and then invoke "hot reload" (save your changes or press the "hot
        // reload" button in a Flutter-supported IDE, or press "r" if you used
        // the command line to start the app).
        //
        // Notice that the counter didn't reset back to zero; the application
        // state is not lost during the reload. To reset the state, use hot
        // restart instead.
        //
        // This works for code too, not just values: Most code changes can be
        // tested with just a hot reload.
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
        useMaterial3: true,
      ),
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
      // home: const CounterWidget(),
      // home: const GetStateObjectRoute(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key, required this.title});

  // This widget is the home page of your application. It is stateful, meaning
  // that it has a State object (defined below) that contains fields that affect
  // how it looks.

  // This class is the configuration for the state. It holds the values (in this
  // case the title) provided by the parent (in this case the App widget) and
  // used by the build method of the State. Fields in a Widget subclass are
  // always marked "final".

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  void _incrementCounter() {
    setState(() {
      // This call to setState tells the Flutter framework that something has
      // changed in this State, which causes it to rerun the build method below
      // so that the display can reflect the updated values. If we changed
      // _counter without calling setState(), then the build method would not be
      // called again, and so nothing would appear to happen.
      _counter++;
    });

    //导航到新路由
    Navigator.push(
      context,
      MaterialPageRoute(builder: (context) {
        return NewRoute();
      }),
    );
  }

  @override
  Widget build(BuildContext context) {
    // This method is rerun every time setState is called, for instance as done
    // by the _incrementCounter method above.
    //
    // The Flutter framework has been optimized to make rerunning build methods
    // fast, so that you can just rebuild anything that needs updating rather
    // than having to individually change instances of widgets.
    return Scaffold(
      appBar: AppBar(
        // TRY THIS: Try changing the color here to a specific color (to
        // Colors.amber, perhaps?) and trigger a hot reload to see the AppBar
        // change color while the other colors stay the same.
        backgroundColor: Theme.of(context).colorScheme.inversePrimary,
        // Here we take the value from the MyHomePage object that was created by
        // the App.build method, and use it to set our appbar title.
        title: Text(widget.title),
      ),
      body: Center(
        // Center is a layout widget. It takes a single child and positions it
        // in the middle of the parent.
        // child: Column(
        //   // Column is also a layout widget. It takes a list of children and
        //   // arranges them vertically. By default, it sizes itself to fit its
        //   // children horizontally, and tries to be as tall as its parent.
        //   //
        //   // Column has various properties to control how it sizes itself and
        //   // how it positions its children. Here we use mainAxisAlignment to
        //   // center the children vertically; the main axis here is the vertical
        //   // axis because Columns are vertical (the cross axis would be
        //   // horizontal).
        //   //
        //   // TRY THIS: Invoke "debug painting" (choose the "Toggle Debug Paint"
        //   // action in the IDE, or press "p" in the console), to see the
        //   // wireframe for each widget.
        //   mainAxisAlignment: MainAxisAlignment.center,
        //   children: <Widget>[
        //     const Text(
        //       'You have pushed the button this many times:',
        //     ),
        //     Text(
        //       '$_counter',
        //       style: Theme.of(context).textTheme.headlineMedium,
        //     ),
        //   ],
        // ),
        child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              RandomWordsWidget(),
            ],
          ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: const Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}

// 测试无状态工具描述ui
class Echo extends StatelessWidget {
  const Echo({
    Key? key,
    required this.text,
    this.backgroundColor = Colors.grey, //默认为灰色
  }) : super(key: key);

  final String text;
  final Color backgroundColor;

  @override
  Widget build(BuildContext context) {
    return Center(
      child: Container(
        color: backgroundColor,
        child: Text(text),
      ),
    );
  }
}

// 测试State状态生命周期
class CounterWidget extends StatefulWidget {
  const CounterWidget({Key? key, this.initValue = 0});

  final int initValue;

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

class _CounterWidgetState extends State<CounterWidget> {
  int _counter = 0;

  @override
  void initState() {
    super.initState();
    //初始化状态
    _counter = widget.initValue;
    print("initState");
  }

  @override
  Widget build(BuildContext context) {
    print("build");
    return Scaffold(
      body: Center(
        child: TextButton(
          child: Text('$_counter'),
          //点击后计数器自增
          onPressed: () => setState(
            () => ++_counter,
          ),
        ),
      ),
    );
  }

  @override
  void didUpdateWidget(CounterWidget oldWidget) {
    super.didUpdateWidget(oldWidget);
    print("didUpdateWidget ");
  }

  @override
  void deactivate() {
    super.deactivate();
    print("deactivate");
  }

  @override
  void dispose() {
    super.dispose();
    print("dispose");
  }

  @override
  void reassemble() {
    super.reassemble();
    print("reassemble");
  }

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    print("didChangeDependencies");
  }
}

//在 widget 树中获取State对象
class GetStateObjectRoute extends StatefulWidget {
  const GetStateObjectRoute({Key? key}) : super(key: key);

  @override
  State<GetStateObjectRoute> createState() => _GetStateObjectRouteState();
}

class _GetStateObjectRouteState extends State<GetStateObjectRoute> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("子树中获取State对象"),
      ),
      body: Center(
        child: Column(
          children: [
            Builder(builder: (context) {
              return ElevatedButton(
                onPressed: () {
                  // // 查找父级最近的Scaffold对应的ScaffoldState对象
                  // ScaffoldState _state = context.findAncestorStateOfType<ScaffoldState>()!;
                  // // 打开抽屉菜单
                  // _state.openDrawer();

                  // // 直接通过of静态方法来获取ScaffoldState
                  // ScaffoldState _state=Scaffold.of(context);
                  // // 打开抽屉菜单
                  // _state.openDrawer();

                  ScaffoldMessenger.of(context).showSnackBar(
                    SnackBar(content: Text("我是SnackBar")),
                  );
                },
                child: Text('打开抽屉菜单1'),
              );
            }),
          ],
        ),
      ),
      drawer: Drawer(),
    );
  }
}

// 路由管理，就是页面跳转
class NewRoute extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("New route"),
      ),
      body: Center(
        child: Text("This is new route"),
      ),
    );
  }
}

class RandomWordsWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    // 生成随机字符串
    final wordPair = WordPair.random();
    return Padding(
      padding: const EdgeInsets.all(8.0),
      child: Text(wordPair.toString()),
    );
  }
}