bottomNavigationBar如何通过ontab在flutter中重建同一页面？

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _selectedIndex = 0;

  List<Widget> _pages = [
    Page1(),
    Page2(),
    Page3(),
  ];

  void _onTabTapped(int index) {
    setState(() {
      _selectedIndex = index;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Bottom Navigation Bar'),
      ),
      body: _pages[_selectedIndex],
      bottomNavigationBar: BottomNavigationBar(
        currentIndex: _selectedIndex,
        onTap: _onTabTapped,
        items: [
          BottomNavigationBarItem(
            icon: Icon(Icons.home),
            label: 'Page 1',
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.business),
            label: 'Page 2',
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.school),
            label: 'Page 3',
          ),
        ],
      ),
    );
  }
}