如何在Flutter中创建垂直滚动的PageView？

import 'package:flutter/material.dart';

@override
Widget build(BuildContext context) {
  return Scaffold(
    appBar: AppBar(
      title: Text('垂直滚动的PageView'),
    ),
    body: PageView.builder(
      scrollDirection: Axis.vertical,
      itemCount: 3,
      itemBuilder: (BuildContext context, int index) {
        return Container(
          color: Colors.blue,
          child: Center(
            child: Text(
              '页面 $index',
              style: TextStyle(fontSize: 24, color: Colors.white),
            ),
          ),
        );
      },
    ),
  );
}