如何在颤动中显示AppBar下方的警示栏

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Shaking AppBar',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: ShakingAppBar(),
    );
  }
}

class ShakingAppBar extends StatefulWidget {
  @override
  _ShakingAppBarState createState() => _ShakingAppBarState();
}

class _ShakingAppBarState extends State<ShakingAppBar> with SingleTickerProviderStateMixin {
  AnimationController _animationController;
  bool _isShaking = false;

  @override
  void initState() {
    super.initState();
    _animationController = AnimationController(
      vsync: this,
      duration: Duration(milliseconds: 200),
    );
  }

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

  void _startShaking() {
    setState(() {
      _isShaking = true;
    });
    _animationController.repeat(reverse: true);
  }

  void _stopShaking() {
    setState(() {
      _isShaking = false;
    });
    _animationController.stop();
  }

  void _showAlert() {
    showDialog(
      context: context,
      builder: (BuildContext context) {
        return AlertDialog(
          title: Text('Alert'),
          content: Text('This is an alert message.'),
          actions: [
            FlatButton(
              child: Text('OK'),
              onPressed: () {
                Navigator.of(context).pop();
              },
            ),
          ],
        );
      },
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Shaking AppBar'),
        actions: [
          IconButton(
            icon: Icon(Icons.warning),
            onPressed: _showAlert,
          ),
        ],
      ),
      body: GestureDetector(
        onLongPress: _startShaking,
        onLongPressEnd: (_) => _stopShaking(),
        child: ListView(
          children: [
            Container(
              height: _isShaking ? 100 : 0,
              color: Colors.red,
              child: Center(
                child: Text(
                  'Shaking Alert',
                  style: TextStyle(
                    color: Colors.white,
                    fontSize: 20,
                  ),
                ),
              ),
            ),
            ListTile(
              title: Text('Item 1'),
            ),
            ListTile(
              title: Text('Item 2'),
            ),
            ListTile(
              title: Text('Item 3'),
            ),
            // Add more list items as needed
          ],
        ),
      ),
    );
  }
}