准备工作
开发环境：
设备：mac电脑
开发工具：Visual Studio Code 版本1.57.0
其他工具：Android Studio、Xcode、Chrome
插件：Visual Studio Code安装Flutter插件，Flutter使用的是Dart语言，安装了Flutter插件，自带就下载了Dart插件
接下来，开始体验Flutter的开发之旅吧！
新建项目
快捷键：shift+comman+P，新建flutter项目
新建项目
目录结构看下图：
目录结构
作为初学者，目前我们主要看这两个文件，main.dart和pubspec.yaml，main.dart是项目的初始化入口，根组件设置主要在这个文件里，体验flutter开发的代码主要在这里写；pubspec.yaml主要是flutter开发的配置文件，里面包含项目的信息、SDK版本、第三方package依赖，以后的开发过程中，我们肯定会用到很多第三方的组件，这里添加第三方组件也很简单，如下图：
配置文件
在dependencies下添加第三方组件，
cupertino_icons就是新建flutter项目时自带的一个第三方组件，后面是它的版本号，这里版本号有不同的设置方法，后面另说。
现在来说说main.dart文件的代码结构：
import 'package:flutter/material.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
// 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 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: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
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;
@override
_MyHomePageState 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(
// 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>[
Text(
'You have pushed the button this many times:123',
),
Text(
'$_counter',
style: Theme.of(context).textTheme.headline4,
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: Icon(Icons.add),
), // This trailing comma makes auto-formatting nicer for build methods.
);
}
}
void main() {}是项目初始化的主入口
class MyApp extends StatelessWidget {}是自定义的一个无状态组件，默认会有一个build方法；
class MyHomePage extends StatefulWidget {}是自定义的一个有状态的组件，默认会有class _MyHomePageState extends State<MyHomePage> {}State类。
运行
了解完上面的基本结构，现在我们看看如何运行代码，如下图：
运行方法
选择设备
运行结果：
运行结果
现在，我们可以体验一下flutter的另一个高效开发的技能：
热重载，随意修改代码中文本上的内容，保存就可以看到页面上已动态刷新的内容。
结语
好了，以上就是从新建项目到运行第一个项目的过程，如有问题，欢迎指正哦！
题外话：虽然网上教程很多，写的比我全面以及好的多，但个人觉得有古话说的好：好记性不如烂笔头，以自己的理解记录下学习的过程是一个很好的学习方法，若有问题，欢迎指正，必认真修改！愿与大家共勉~
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