【Flutter】创建BMI计算器应用并添加依赖和打包

😏★,°:.☆(￣▽￣)/$:.°★ 😏
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});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'frank_test',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const HomeScreen(),
    );
  }
}

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

  @override
  Widget 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});

  @override
  State<TimeDisplayScreen> createState() => _TimeDisplayScreenState();
}

class _TimeDisplayScreenState extends State<TimeDisplayScreen> {
  String _currentTime = '';
  late Timer _timer;

  @override
  void initState() {
    super.initState();
    _updateTime();
    _timer = Timer.periodic(const Duration(seconds: 1), (timer) {
      _updateTime();
    });
  }

  @override
  void dispose() {
    _timer.cancel();
    super.dispose();
  }

  void _updateTime() {
    setState(() {
      _currentTime = DateFormat('yyyy-MM-dd HH:mm:ss').format(DateTime.now());
    });
  }

  @override
  Widget 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});

  @override
  State<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';
    }
  }

  @override
  void dispose() {
    _heightController.dispose();
    _weightController.dispose();
    super.dispose();
  }

  @override
  Widget 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: flutter
  intl: ^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。