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编写第一个flutter应用(table)组件化

发布时间：2026-07-04 23:04:07编辑：雪饮阅读（）

上篇中做了一个table的示例，那其实那个table的代码还是挺多的，全部放到main.dart上面毕竟还是不太好，未来可能首页是由各种组件组成的。
所以抽离一个组件，然后main.dart仅仅加载组件即可。
所以main.dart精简后如：
import 'package:flutter/material.dart';
import 'info_table.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 purple 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: .fromSeed(seedColor: Colors.deepPurple),
      ),
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}
 
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++;
    });
  }
 
  @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: .center,
          children: [
            const Text('You have pushed the button this many times:'),
            const InfoTable(),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.headlineMedium,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: const Icon(Icons.add),
      ),
    );
  }
}
 
然后在main.dart的同目录建立这个被加载的组件
info_table.dart:
import 'package:flutter/material.dart';
 
class InfoTable extends StatefulWidget {
  const InfoTable({super.key});
 
  @override
  State<InfoTable> createState() => _InfoTableState();
}
 
class _InfoTableState extends State<InfoTable> {
  String _selectedGender = '男';
 
  Widget _buildHeaderCell(String text) {
    return TableCell(
      child: Padding(
        padding: const EdgeInsets.all(8.0),
        child: Text(text, style: const TextStyle(fontWeight: FontWeight.bold)),
      ),
    );
  }
 
  Widget _buildInputCell(String hint) {
    return TableCell(
      child: Padding(
        padding: const EdgeInsets.all(8.0),
        child: TextField(
          decoration: InputDecoration(
            hintText: hint,
            border: const OutlineInputBorder(),
          ),
        ),
      ),
    );
  }
 
  Widget _buildNumberInputCell() {
    return TableCell(
      child: Padding(
        padding: const EdgeInsets.all(8.0),
        child: TextField(
          keyboardType: TextInputType.number,
          decoration: const InputDecoration(
            hintText: '请输入年龄',
            border: OutlineInputBorder(),
          ),
        ),
      ),
    );
  }
 
  Widget _buildDropdownCell() {
    return TableCell(
      child: Padding(
        padding: const EdgeInsets.all(8.0),
        child: DropdownButton<String>(
          value: _selectedGender,
          onChanged: (String? newValue) {
            setState(() {
              _selectedGender = newValue!;
            });
          },
          items: <String>['男', '女'].map<DropdownMenuItem<String>>((
            String value,
          ) {
            return DropdownMenuItem<String>(value: value, child: Text(value));
          }).toList(),
        ),
      ),
    );
  }
 
  @override
  Widget build(BuildContext context) {
    return Table(
      border: TableBorder.all(),
      columnWidths: const {
        0: FlexColumnWidth(1),
        1: FlexColumnWidth(1),
        2: FlexColumnWidth(1),
      },
      children: [
        TableRow(
          children: [
            _buildHeaderCell('姓名'),
            _buildHeaderCell('年龄'),
            _buildHeaderCell('性别'),
          ],
        ),
        TableRow(
          children: [
            _buildInputCell('请输入姓名'),
            _buildNumberInputCell(),
            _buildDropdownCell(),
          ],
        ),
      ],
    );
  }
}