根据带有 BottomNavigationBar 的页面更改 AppBar 标题

Question

我正在尝试根据用户所在的页面更改 AppBar 标题 - 页面由加载不同类（页面）的BottomNavigationBar 控制

我设法改变这一点的唯一方法是为每个页面包含一个应用程序栏，我认为这不是继续前进的方式。

class HomePage extends StatefulWidget {
  final String title;

  HomePage({Key key, this.auth, this.userId, this.onSignedOut, this.title})
      : super(key: key);

  final BaseAuth auth;
  final VoidCallback onSignedOut;
  final String userId;

  @override
  State<StatefulWidget> createState() => new _HomePageState();
}

class _HomePageState extends State<HomePage> {
  int _currentIndex = 0;
  final List<Widget> _children = [
    Projects(),
    TimedProject(),
    Overview(),
    Clients(),
  ];

  GlobalKey<ScaffoldState> _scaffoldKey = new GlobalKey();

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      key: _scaffoldKey,
      appBar: AppBar(
        title: Text('TITLE I NEED TO CHANGE DEPENDING ON PAGE',
          style: TextStyle(color: Colors.black),
        ),

        backgroundColor: Colors.white,
      ),
      endDrawer: AppDrawer(),
      body: _children[_currentIndex],
      bottomNavigationBar: BottomNavigationBar(
        onTap: onTabTapped,
        currentIndex: _currentIndex,
        selectedItemColor: Theme.of(context).primaryColor,
        type: BottomNavigationBarType.fixed,
        items: [
          new BottomNavigationBarItem(
            icon: Icon(Icons.storage),
            title: Text('Jobs'),
          ),
          new BottomNavigationBarItem(
            icon: Icon(Icons.timer),
            title: Text('Timer'),
          ),
          new BottomNavigationBarItem(
            icon: Icon(Icons.pie_chart_outlined),
            title: Text('Overview'),
          ),
          new BottomNavigationBarItem(
              icon: Icon(Icons.supervisor_account), title: Text('Clients'))
        ],
      ),
    );
  }

  void onTabTapped(int index) {
    setState(() {
      _currentIndex = index;
    });
  }
}

Answer 1

创建一个保存 appbar 标题的变量，或者您可以使用在 HomePage 类中传递的相同标题变量，但您必须删除 final。

如果您在 HomePage 类中使用 title 变量，请确保使用“widget.title”

class HomePage extends StatefulWidget {
  final String title;

  HomePage({Key key, this.auth, this.userId, this.onSignedOut, this.title})
      : super(key: key);

  final BaseAuth auth;
  final VoidCallback onSignedOut;
  final String userId;

  @override
  State<StatefulWidget> createState() => new _HomePageState();
 }

class _HomePageState extends State<HomePage> {
  int _currentIndex = 0;
  String _title;

  final List<Widget> _children = [
     Projects(),
     TimedProject(),
     Overview(),
     Clients(),
  ];

  GlobalKey<ScaffoldState> _scaffoldKey = new GlobalKey();

 @override
  initState(){
    _title = 'Some default value';
  }


  @override
  Widget build(BuildContext context) {
     return new Scaffold(
       key: _scaffoldKey,
       appBar: AppBar(
       title: Text(_title,
          style: TextStyle(color: Colors.black),
       ),

       backgroundColor: Colors.white,
      ),
  endDrawer: AppDrawer(),
  body: _children[_currentIndex],
  bottomNavigationBar: BottomNavigationBar(
    onTap: onTabTapped,
    currentIndex: _currentIndex,
    selectedItemColor: Theme.of(context).primaryColor,
    type: BottomNavigationBarType.fixed,
    items: [
      new BottomNavigationBarItem(
        icon: Icon(Icons.storage),
        title: Text('Jobs'),
      ),
      new BottomNavigationBarItem(
        icon: Icon(Icons.timer),
        title: Text('Timer'),
      ),
      new BottomNavigationBarItem(
        icon: Icon(Icons.pie_chart_outlined),
        title: Text('Overview'),
      ),
      new BottomNavigationBarItem(
          icon: Icon(Icons.supervisor_account), title: Text('Clients'))
    ],
  ),
);
}

   void onTabTapped(int index) {
     setState(() {
     _currentIndex = index;
      switch(index) { 
       case 0: { _title = 'Jobs'; } 
       break; 
       case 1: { _title = 'Timer'; } 
       break;
       case 2: { _title = 'Overview'; } 
       break;
       case 3: { _title = 'Clients'; } 
       break; 
      } 
     });
   }
}