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这篇文章主要介绍创建BMI计算器应用并添加依赖和打包。
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😏1. BMI计算器示例

继续前面第一篇的，在显示时间的基础上增加BMI计算器，为了方便，各个功能分成单独dart文件实现，共3个文件。

main.dart

import 'package:flutter/material.dart';
import 'time_display.dart';
import 'bmi_calculator.dart';void main() {runApp(const MyApp());
}class MyApp extends StatelessWidget {const MyApp({super.key});@overrideWidget build(BuildContext context) {return MaterialApp(title: 'frank_test',theme: ThemeData(primarySwatch: Colors.blue,),home: const HomeScreen(),);}
}class HomeScreen extends StatelessWidget {const HomeScreen({super.key});@overrideWidget build(BuildContext context) {return Scaffold(appBar: AppBar(title: const Text('frank_test'),),body: SingleChildScrollView(child: Column(children: const [TimeDisplayScreen(),BMICalculator(),],),),);}
}

time_display.dart

import 'package:flutter/material.dart';
import 'package:intl/intl.dart';
import 'dart:async';class TimeDisplayScreen extends StatefulWidget {const TimeDisplayScreen({super.key});@overrideState<TimeDisplayScreen> createState() => _TimeDisplayScreenState();
}class _TimeDisplayScreenState extends State<TimeDisplayScreen> {String _currentTime = '';late Timer _timer;@overridevoid initState() {super.initState();_updateTime();_timer = Timer.periodic(const Duration(seconds: 1), (timer) {_updateTime();});}@overridevoid dispose() {_timer.cancel();super.dispose();}void _updateTime() {setState(() {_currentTime = DateFormat('yyyy-MM-dd HH:mm:ss').format(DateTime.now());});}@overrideWidget build(BuildContext context) {return Card(elevation: 4,margin: const EdgeInsets.all(16),child: Padding(padding: const EdgeInsets.all(16),child: Column(children: [const Text('当前时间',style: TextStyle(fontSize: 20, fontWeight: FontWeight.bold),),const SizedBox(height: 16),Text(_currentTime,style: const TextStyle(fontSize: 24),),],),),);}
}

bmi_caculator.dart

import 'package:flutter/material.dart';class BMICalculator extends StatefulWidget {const BMICalculator({super.key});@overrideState<BMICalculator> createState() => _BMICalculatorState();
}class _BMICalculatorState extends State<BMICalculator> {final TextEditingController _heightController = TextEditingController();final TextEditingController _weightController = TextEditingController();double _bmiResult = 0;String _bmiCategory = '';void _calculateBMI() {final double height = double.tryParse(_heightController.text) ?? 0;final double weight = double.tryParse(_weightController.text) ?? 0;if (height > 0 && weight > 0) {setState(() {_bmiResult = weight / ((height / 100) * (height / 100));_updateBMICategory();});}}void _updateBMICategory() {if (_bmiResult < 18.5) {_bmiCategory = '偏瘦';} else if (_bmiResult < 24) {_bmiCategory = '正常';} else if (_bmiResult < 28) {_bmiCategory = '过重';} else {_bmiCategory = '肥胖';}}@overridevoid dispose() {_heightController.dispose();_weightController.dispose();super.dispose();}@overrideWidget build(BuildContext context) {return Card(elevation: 4,margin: const EdgeInsets.all(16),child: Padding(padding: const EdgeInsets.all(16),child: Column(children: [const Text('BMI 计算器',style: TextStyle(fontSize: 20, fontWeight: FontWeight.bold),),const SizedBox(height: 16),TextField(controller: _heightController,keyboardType: TextInputType.number,decoration: const InputDecoration(labelText: '身高 (cm)',border: OutlineInputBorder(),),),const SizedBox(height: 16),TextField(controller: _weightController,keyboardType: TextInputType.number,decoration: const InputDecoration(labelText: '体重 (kg)',border: OutlineInputBorder(),),),const SizedBox(height: 16),ElevatedButton(onPressed: _calculateBMI,child: const Text('计算 BMI'),),const SizedBox(height: 16),if (_bmiResult > 0)Column(children: [Text('BMI: ${_bmiResult.toStringAsFixed(1)}',style: const TextStyle(fontSize: 18),),Text('状态: $_bmiCategory',style: TextStyle(fontSize: 18,color: _getCategoryColor(),),),],),],),),);}Color _getCategoryColor() {switch (_bmiCategory) {case '偏瘦':return Colors.blue;case '正常':return Colors.green;case '过重':return Colors.orange;case '肥胖':return Colors.red;default:return Colors.black;}}
}

😊2. 添加依赖

如果程序依赖一些库，比如这里依赖intl，需要在pubspec.yaml文件中添加：

dependencies:flutter:sdk: flutterintl: ^0.18.1

😆3. 应用打包

打包web：

flutter build web --release
# 运行
cd build/web
python3 -m http.server 8000

打包linux：

flutter build linux --release
./build/linux/x64/release/bundle/frank_test

以上。