flutter如何实现手动控制需要缓存的页面

需要实现的效果

1 不同页面切换后能够有缓存效果
2 可以手动设置哪些页面需要缓存,哪些页面不需要
3 再次点击当前页面的底部icon时回到顶部

// main.dart
import 'package:flutter/material.dart';
import 'package:flutter_demo/detail.dart';
import 'package:flutter_demo/home.dart';

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      home: MyStatefulWidget(),
    );
  }
}

class MyStatefulWidget extends StatefulWidget {
  const MyStatefulWidget({super.key});

  @override
  State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
}

class _MyStatefulWidgetState extends State<MyStatefulWidget> {
  int _selectedIndex = 0;
  late PageController _pageController;
  List<Widget> pages = [HomeWidget(), DetailWidget()];

  @override
  void initState() {
    super.initState();
    _pageController =
        PageController(initialPage: _selectedIndex, keepPage: true);
  }

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

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('home'),
      ),
      // 手动管理需要缓存的页面
      body: PageView.builder(
        controller: _pageController,
        physics: NeverScrollableScrollPhysics(),//禁止页面左右滑动切换
        onPageChanged: (value) {
          _pageController.jumpToPage(value);
          setState(() {
            _selectedIndex = value;
          });
        },
        itemCount: pages.length,
        itemBuilder: (context, index) => pages.elementAt(index),
      ),
      bottomNavigationBar: BottomNavigationBar(
        items: const <BottomNavigationBarItem>[
          BottomNavigationBarItem(
            icon: Icon(Icons.home),
            label: '首页',
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.open_in_new_rounded),
            label: '详情',
          ),
        ],
        currentIndex: _selectedIndex,
        selectedItemColor: Colors.amber[800],
        onTap: (int index) {
          setState(
            () {
              _selectedIndex = index;
              _pageController.jumpToPage(index);
            },
          );
        },
      ),
    );
  }
}

// home.dart
import 'package:flutter/material.dart';

class HomeWidget extends StatefulWidget {
  const HomeWidget({Key? key}) : super(key: key);

  @override
  State<HomeWidget> createState() => _HomeWidgetState();
}

class _HomeWidgetState extends State<HomeWidget>
    with AutomaticKeepAliveClientMixin {
  @override
  void initState() {
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return ListView.separated(
        itemBuilder: (BuildContext context, int index) {
          return Center(
            child: Text(
              'Item $index',
            ),
          );
        },
        separatorBuilder: (BuildContext context, int index) => const Divider(
              thickness: 1,
            ),
        itemCount: 50);
  }
   
  // 开启缓存
  @override
  bool get wantKeepAlive => true;
}

// detail.dart
import 'package:flutter/material.dart';

class DetailWidget extends StatefulWidget {
  const DetailWidget({Key? key}) : super(key: key);

  @override
  State<DetailWidget> createState() => _DetailWidgetState();
}

class _DetailWidgetState extends State<DetailWidget> {
  @override
  void initState() {
    super.initState();
    print('detail');
  }

  @override
  Widget build(BuildContext context) {
    return const Text('detail');
  }
}