[Flutter]Drawer

class MyApp extends StatefulWidget {
  @override
  myAppState createState() => myAppState();
}

class myAppState extends State<MyApp> {
  //目前選擇頁索引值
  int currentIndex = 0; //預設值

  final pages = [One(), Two(), Three()];

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: AppBar(
        title: Text('DrawerDemo'),
      ),
      drawer: Drawer(
        child: ListView(
          children: <Widget>[
            const DrawerHeader(
              decoration: BoxDecoration(
                color: Colors.blue,
              ),
              child: Text('Drawer Header'),
            ),
            //選單
            ListTile(
              leading: new CircleAvatar(child: Icon(your_icon)),
              title: Text('第一頁'),
              onTap: () {
                itemClick(0);
              },
            ),
            ListTile(
              leading: new CircleAvatar(child: Icon(your_icon)),
              title: Text('第二頁'),
              onTap: () {
                itemClick(1);
              },
            ),
            ListTile(
              leading: new CircleAvatar(child: Icon(your_icon)),
              title: Text('第三頁'),
              onTap: () {
                itemClick(2);
              },
            ),
          ],
        ),
      ),
      body: pages[currentIndex],
    );
  }

  void itemClick(int index) {
    setState(() {
      currentIndex = index;
      Navigator.of(context).pop();
    });
  }
}