状态保持一般都会说要加 SingleTickerProviderStateMixin 或AutomaticKeepAliveClientMixin

class _HomePageState extends State<HomePage>
with SingleTickerProviderStateMixin {

  @override
  Widget build(BuildContext context) {
super.build(context);
return Scaffold(
  appBar: AppBar(
    title: Text('云台法律咨询'),
  ),
  body: HomeScreen(),
);
}
//必须加下面的状态保持
@override
bool get wantKeepAlive => true;

}

但是以上代码要实现状态保持是不够的，还需要在tabbar里面添加如下代码

                                                                                                            class _CustormTabbarPageState extends State<CustormTabbarPage>
with SingleTickerProviderStateMixin {

    final _BottomNavigationColor = Colors.black54;
    final _SelectedColor = Colors.blueAccent;
    int _currentIndex = 0;
    List<Widget> pageList = List();
  final PageController _controller =       PageController(initialPage: 0);
    @override
  void initState() {
    // pageList
    pageList..add(HomePage());
    pageList..add(MinePage());
super.initState();
  }

    @override
  void dispose() {
    super.dispose();
    }

  @override
  Widget build(BuildContext context) {
// super.build(context);
return Scaffold(
  // body: PageView(
  //   controller: _controller,
  //   children: [HomePage(), MinePage()],
  // ),

  body: IndexedStack(
    index: _currentIndex,
    children: pageList,
  ),
  // body: pageList[_currentIndex],

  bottomNavigationBar: BottomNavigationBar(
      items: [
        BottomNavigationBarItem(
          icon: Icon(
            Icons.home,
          ),
          title: Text('首页'),
        ),
        BottomNavigationBarItem(
          icon: Icon(
            Icons.people,
          ),
          title: Text('我的'),
        ),
      ],
      currentIndex: _currentIndex,
      fixedColor: _SelectedColor,
      onTap: (index) {
        // _controller.jumpToPage(index);

        setState(() {
          _currentIndex = index;
        });
      }),
);
  }
}

必须使用IndexedStack 才行