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這是一個跨端的時代，各種跨端框架你方唱罷我登場，今天小編帶領大家來入門Flutter，看它到底有沒有傳說中的那么好。磨刀不誤砍柴工，先來安裝Flutter開發環境吧。先安裝Android Studio，然后在Settings->Plugin里選擇 Browser Repositories，在線安裝Flutter插件。安裝Flutter插件時，它會提示自動安裝Dart語言插件。

安裝插件

插件安裝好后，需要再去Flutter中文官網下載SDK(比英文官網下載速度快很多)，根據官網要求設置好Flutter Path及Git Path的系統環境變量。然后在命令行窗口輸入flutter doctor命令，它會自動關聯下載Dart SDK，如果發現下載比較慢，可以將FLUTTER_STORAGE_BASE_URL和PUB_HOSTED_URL兩個網址映射到中文站，并添加到系統環境變量里。flutter doctor多次運行后，會看到提示小編的android studio版本太低(我的是2.3版本，而flutter要求3.0版本以上)，倒霉了，得升級android studio，差不多1個G，可夠我下載的了，先去泡杯咖啡，再繼續。

flutter doctor命令 Flutter入門，寫一個跨平臺的Hello World

檢查結果

新版android studio安裝好后，按照最開始的步驟，在settings->plugins菜單里安裝flutter 和 dart插件，然后就可以在File菜單開始New一個flutter的Project啦!

new flutter project

工程建好后，我們可以看到 flutter app的代碼是用Dart語言編寫的，語法與Java非常類似，幾乎沒有什么新的學習成本。從MyApp的代碼來看，我們可以知道flutter里的界面都是用Widget來搭建的，這一點與Android不同，后面小編再帶大家細細品味Widget。

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,

        // This makes the visual density adapt to the platform that you run

        // the app on. For desktop platforms, the controls will be smaller and

        // closer together (more dense) than on mobile platforms.

        visualDensity: VisualDensity.adaptivePlatformDensity,

      ),

      home: MyHomePage(title: 'Flutter Hello World!'),

    );

  }

}