Flutter切換tab後保留tab狀態

BottomNavigationBar+PageView+AutomaticKeepAliveClientMixin

要點

子頁面的class

class _HomePageState with AutomaticKeepAliveClientMixin{//要點1
 
 
  @override
  bool get wantKeepAlive => true;//要點2
 
  Widget build(BuildContext context){
    super.build(context);//要點3
  }

光上面其實還不夠，還須要搭配其餘Widget使用，例如BottomNavigationBar+PageView活着TabBar+TabbarView，這樣頁面纔不會銷燬。

//PageView是重點的重點

Scaffold(
        body:PageView.builder(
          physics: NeverScrollableScrollPhysics(),//禁止頁面左右滑動切換
          controller: _pageController,
          onPageChanged: _pageChanged,
          itemCount: _pages.length,
          itemBuilder: (context,index)=>_pages[index]
        )
        bottomNavigationBar:...
)

class MyApp extends StatefulWidget{
  @override
  _MyAppState createState() => _MyAppState();
}
 
class _MyAppState extends State<MyApp>{
  var _pages = [HomePage(),ListViewDemo(),DemoPage(),UserListPage()]; 
  int _tabIndex = 0;
 
  var _pageController =PageController();
 
  @override
  void dispose() {
    super.dispose();
    _pageController.dispose();
  }
 
  Widget build(BuildContext context){
    return MaterialApp(
      theme: ThemeData(
        primaryColor: Colors.pinkAccent
      ),
      
      home:Scaffold(
        body:PageView.builder(//要點1
          physics: NeverScrollableScrollPhysics(),//禁止頁面左右滑動切換
          controller: _pageController,
          onPageChanged: _pageChanged,//回調函數
          itemCount: _pages.length,
          itemBuilder: (context,index)=>_pages[index]
        ),
        bottomNavigationBar:BottomNavigationBar(
          items: <BottomNavigationBarItem>[
            BottomNavigationBarItem(title:Text('主頁'),icon: Icon(Icons.home)),
            BottomNavigationBarItem(title:Text('商城'),icon: Icon(Icons.shopping_basket)),
            BottomNavigationBarItem(title:Text('測試'),icon: Icon(Icons.pageview)),
            BottomNavigationBarItem(title:Text('個人'),icon: Icon(Icons.account_box)),
          ],
          onTap: (index){
            print('onTap');
            _pageController.jumpToPage(index);
  
          },      
          type:BottomNavigationBarType.fixed,
          currentIndex: _tabIndex,  
        ),
       
        
      )    
      );
  }
 
  void _pageChanged(int index){
    print('_pageChanged');
    setState(() {
      if(_tabIndex != index)
        _tabIndex = index;
    });
  }
  
}

class DemoPage extends StatefulWidget {
  _DemoPageState createState() => _DemoPageState();
}
 
class _DemoPageState extends State<DemoPage> with AutomaticKeepAliveClientMixin{//要點1
  int _count = 0;
 
  @override
  bool get wantKeepAlive => true;//要點2
 
  @override
  Widget build(BuildContext context) {
    super.build(context);//要點3
    return Scaffold(
      appBar: AppBar(title:Text('Demo Page')),
      body: Center(child:Text('當前計數:$_count')),
      floatingActionButton: FloatingActionButton(
        child: Icon(Icons.add),
        onPressed: (){
          setState(() {
            _count++;
          });
        },
      ),
    );
  }
}

---

來源：CSDN
原文：https://blog.csdn.net/weixin_...
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