Flutter从表单中提取所有键值

import 'package:flutter/material.dart';

class MyForm extends StatefulWidget {
  @override
  _MyFormState createState() => _MyFormState();
}

class _MyFormState extends State<MyForm> {
  final _formKey = GlobalKey<FormState>();
  Map<String, dynamic> _formData = {};

  @override
  Widget build(BuildContext context) {
    return Form(
      key: _formKey,
      child: Column(
        children: [
          TextFormField(
            decoration: InputDecoration(labelText: '姓名'),
            validator: (value) {
              if (value.isEmpty) {
                return '请输入姓名';
              }
              return null;
            },
            onSaved: (value) {
              _formData['name'] = value;
            },
          ),
          TextFormField(
            decoration: InputDecoration(labelText: '年龄'),
            validator: (value) {
              if (value.isEmpty) {
                return '请输入年龄';
              }
              return null;
            },
            onSaved: (value) {
              _formData['age'] = int.parse(value);
            },
          ),
          RaisedButton(
            onPressed: () {
              if (_formKey.currentState.validate()) {
                _formKey.currentState.save();
                // 提交表单，处理数据
                _extractFormData();
              }
            },
            child: Text('提交'),
          ),
        ],
      ),
    );
  }

  void _extractFormData() {
    // 从表单中提取所有键值对
    print(_formData);
  }
}

void main() {
  runApp(MaterialApp(
    home: Scaffold(
      appBar: AppBar(
        title: Text('表单示例'),
      ),
      body: MyForm(),
    ),
  ));
}