如何在Flutter中制作自定义AppBar，就像在汉密尔顿flutter应用中一样？

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: CustomAppBar(), // 使用自定义的AppBar
        body: Center(
          child: Text('Hello, Flutter!'),
        ),
      ),
    );
  }
}

class CustomAppBar extends StatefulWidget implements PreferredSizeWidget {
  @override
  _CustomAppBarState createState() => _CustomAppBarState();

  @override
  Size get preferredSize => Size.fromHeight(kToolbarHeight);
}

class _CustomAppBarState extends State<CustomAppBar> {
  @override
  Widget build(BuildContext context) {
    return AppBar(
      backgroundColor: Colors.blue, // 设置背景颜色
      title: Text('Custom AppBar'), // 设置标题
      leading: IconButton(
        icon: Icon(Icons.menu), // 设置左侧图标
        onPressed: () {
          // 处理左侧图标点击事件
        },
      ),
      actions: [
        IconButton(
          icon: Icon(Icons.search), // 设置右侧图标
          onPressed: () {
            // 处理右侧图标点击事件
          },
        ),
      ],
    );
  }
}