前言

在flutter项目中使用ListView或者PageView等有滚动条组件的时候，切换页面的时候，再切换回来会丢失之前的滑动状态，这个时候就需要需要使用缓存功能

缓存类

import 'package:flutter/material.dart';class KeepAliveWrapper extends StatefulWidget {const KeepAliveWrapper({Key? key, @required this.child, this.keepAlive = true}): super(key: key);final Widget? child;final bool keepAlive;@overrideState<KeepAliveWrapper> createState() => _KeepAliveWrapperState();
}class _KeepAliveWrapperState extends State<KeepAliveWrapper>with AutomaticKeepAliveClientMixin {@overrideWidget build(BuildContext context) {return widget.child!;}@overridebool get wantKeepAlive => widget.keepAlive;  
}

使用

在需要缓存的组件使用KeepAliveWrapper包裹一下即可

@overrideWidget build(BuildContext context) {return KeepAliveWrapper(child: Scaffold(body: Stack(children: [_homePage(), _appBar()],),));}