Flutter 在appbar中使用pageview进行颤振

在我的应用程序中，我想在AppBar中显示一些容器，如PageView，我想更改页面视图的索引以显示特定视图，例如，假设我有4个小部件树，如：

Container( width: double.infinity, child: const Text( 'Appbar 1' ), ),
Container( width: double.infinity, child: const Text( 'Appbar 2' ), ),
Container( width: double.infinity, child: const Text( 'Appbar 3' ), ),
Container( width: double.infinity, child: const Text( 'Appbar 4' ), ),

我想把它们放到页面视图中，然后把页面视图放到应用程序栏中

---

您需要将页面视图放在一个容器中，并定义宽度和高度

class AppToolbar extends State<ApplicationToolbar> {
  PageController _appBarPageController;

  @override
  void initState() {
    super.initState();
    _appBarPageController = PageController(initialPage: 0, keepPage: true);
  }
  @override
  Widget build(BuildContext context) {
    return AppBar(
        automaticallyImplyLeading: false,
        elevation: 8.0,
        titleSpacing: 0.0,
        title: PageView(
          controller: _appBarPageController,
          scrollDirection: Axis.vertical,
          children: <Widget>[
            Container( width: double.infinity, child: const Text( 'Appbar 1' ), ),
            Container( width: double.infinity, child: const Text( 'Appbar 2' ), ),
            Container( width: double.infinity, child: const Text( 'Appbar 3' ), ),
            Container( width: double.infinity, child: const Text( 'Appbar 4' ), ),
          ],
        )
    );
  }

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

════════ (16) Exception caught by rendering library ═══════
RenderBox was not laid out: RenderRepaintBoundary#3a85a relayoutBoundary=up14 NEEDS-PAINT
'package:flutter/src/rendering/box.dart':
Failed assertion: line 1694 pos 12: 'hasSize'
The relevant error-causing widget was: 
  AppBar file:///C:/Users/mahdi/AndroidStudioProjects/xxx/lib/ui_helper/widgets/application_toolbar.dart:36:12