如何动态改变appbar的背景颜色？

dependencies:
  flutter:
    sdk: flutter
  material: ^2.0.0

import 'package:flutter/material.dart';

class MyHomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Colors.blue,
        // 其他属性...
      ),
      body: Container(
        // 页面内容...
      ),
    );
  }
}

import 'package:flutter/material.dart';

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  Color appBarColor = Colors.blue;  // 初始颜色为蓝色

  void changeAppBarColor() {
    setState(() {
      appBarColor = Colors.red;  // 修改颜色为红色
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: appBarColor,
        // 其他属性...
      ),
      body: Container(
        // 页面内容...
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () => changeAppBarColor(),  // 点击按钮改变颜色
        child: Icon(Icons.color_lens),
      ),
    );
  }
}