Flutter is Google’s UI toolkit for building beautiful, natively compiled applications for mobile, web, desktop, and embedded devices from a single codebase.

dart 官网

dart 语言基础

dart packages

1. 文件结构

  • myapp
    • android
    • ios
    • web
    • build
    • lib
      • main.dart
      • (需要编写的代码一般都在这)
    • test
    • .gitignore
    • .metadata
    • .packages
    • 项目名.iml
    • pubspec.lock
      • (管理依赖包名及版本)
    • pucspec.yaml
      • (构建发布时的配置文件,name,version)
      • (管理 assets)
  • External Libraries
    • Dart Packages
    • Dart SDK

2. demo 代码

2.1 hello world

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Welcome to Flutter',
      home: Scaffold(
        appBar: AppBar(
          title: const Text('Welcome to Flutter'),
        body: const Center(
          child: Text('Hello World'),

2.2 按钮点击计数

import 'package:flutter/material.dart';

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

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

  // This widget is the root of your application.
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        // This is the theme of your application.
        // Try running your application with "flutter run". You'll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // "hot reload" (press "r" in the console where you ran "flutter run",
        // or simply save your changes to "hot reload" in a Flutter IDE).
        // Notice that the counter didn't reset back to zero; the application
        // is not restarted.
        primarySwatch: Colors.blue,
      home: const MyHomePage(title: 'Flutter Demo Home Page'),

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

  // 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;

  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.

  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(
        // 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.
          // Invoke "debug painting" (press "p" in the console, choose the
          // "Toggle Debug Paint" action from the Flutter Inspector in Android
          // Studio, or the "Toggle Debug Paint" command in Visual Studio Code)
          // to see the wireframe for each widget.
          // 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).
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            const Text(
              'You have pushed the button this many times:',
              style: Theme.of(context).textTheme.headline4,
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: const Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
  • web 测试时,会启用一个新的端口来显示网页
  • android 测试时,会生成一个 40mb 的 apk 包
  • android 构建时,使用指令:
    flutter build apk --split-per-abi
    生成的ARM架构的 APK 大小 5.3 mb

3. 其它说明



快捷键:ctrl + sctrl + \

2. 模式说明

  • debug 模式
    • 更大的性能开销实现了更快速的开发效率
  • profile 模式
  • release 模式

3. 环境说明

按照官网教程配置 flutter 环境,别忘了修改镜像源。


flutter --version
flutter doctor


C:\Users\User>flutter doctor
Doctor summary (to see all details, run flutter doctor -v):
[√] Flutter (Channel stable, 2.5.3, on Microsoft Windows [Version 10.0.22000.282], locale zh-CN)
[√] Android toolchain - develop for Android devices (Android SDK version 31.0.0)
[√] Chrome - develop for the web
[√] Android Studio (version 2020.3)
[√] VS Code (version 1.61.2)
[√] Connected device (3 available)

• No issues found!


uses-material-design: true
cupertino_icons: ^1.0.2

CupertinoIcons class for iOS style icons

注意手机的架构,默认的架构是 X86,生成的 APK 无法安装在 大部分ARM 架构的手机上
构建打包后ARM架构的才能安装,ARM 架构的无法运行在电脑的模拟器上。

4. dart 例子



4.1 类的初始化及类继承
void main(){
  User userOne = User('luigi', 25);
  SuperUser userTwo = SuperUser("alicia", 30);

class User{
  String username;
  int age;
  User(this.username, this.age){}   //注意这里的构建
  void login(){
    print("user logged in");

class SuperUser extends User{
  SuperUser(String name, int age): super(name,age);
  void publish(){
    print("published update");

5. widgets

设计理念:所有界面都是一棵 widget树,每个widget 具有不同属性

  • Scaffold
  • AppBar
    • title
    • centerTitle: true
    • backgroundColor: Colors.red 100
  • Center
  • Text
  • Button
  • FloatingActionButton
    • child
    • onPressed: () {}
  • Row
  • Column
  • Image

6. 做个番茄



这时,可以使用 应用分发平台,它会给你的应用提供一个下载的网页。


flutter 132k⭐



文章作者: ╯晓~
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