5. package資源

1. https://pub.dartlang.org/
2. 開啟pubspec.yaml在dependencies下加入：

   dependencies:
     flutter:
       sdk: flutter
   
     # The following adds the Cupertino Icons font to your application.
     # Use with the CupertinoIcons class for iOS style icons.
     cupertino_icons: ^0.1.2
     url_launcher: ^5.0.1

   在VS Code中，儲存後就會自動下載（但並不在專案中，而是在flutter的安裝目錄下，例如：C:\tools\flutter\.pub-cache\hosted\pub.dartlang.org）

3. 安裝使用從installing就有詳細說明，如：https://pub.dartlang.org/packages/url_launcher#-installing-tab-

4. 完整範例：

   import 'package:flutter/material.dart';
   import 'package:url_launcher/url_launcher.dart';
   
   void main() => runApp(new MyApp());
   
   class MyApp extends StatelessWidget {
     @override
     Widget build(BuildContext context) {
       return new MaterialApp(
         title: '使用工具包',
         home: new Scaffold(
           appBar: new AppBar(
             title: new Text('url_launcher 工具包'),
           ),
           body: new Center(
             child: new RaisedButton(
               onPressed: (){
                 const url='https://schoolweb.tn.edu.tw';
                 launch(url);
               },
               child: new Text('打開集中式校網'),
             ),
           ),
         ),
       );
     }
   }