vue 2 使用
<keep-alive>
<router-view />
</keep-alive>
vue3 使用
<template>
<router-view v-slot="{ Component }">
<transition>
<keep-alive>
<component :is="Component" />
</keep-alive>
</transition>
</router-view>
</template>
vue3 keep-alive 文档地址：
https://v3.cn.vuejs.org/api/built-in-components.html#keep-alive
https://v3.cn.vuejs.org/guide/migration/suspense.html#%E4%BA%8B%E4%BB%B6
