vue3 keep-alive 二级路由缓存方法

以下是Vue3中keep-alive缓存二级路由的方法：

1. 在router/index.js中，为每个二级路由添加meta属性，用于存储需要缓存的组件名称，例如：

const routes = [
  {
    path: '/',
    name: 'Home',
    component: Home
  },
  {
    path: '/about',
    name: 'About',
    component: () => import(/* webpackChunkName: "about" */ '../views/About.vue'),
    meta: {
      keepAlive: true // 需要缓存的组件名称
    }
  },
  {
    path: '/user',
    name: 'User',
    component: () => import(/* webpackChunkName: "user" */ '../views/User.vue')
  },
  {
    path: '/user/profile',
    name: 'Profile',
    component: () => import(/* webpackChunkName: "profile" */ '../views/Profile.vue'),
    meta: {
      keepAlive: true // 需要缓存的组件名称
    }
  }
]

2. 在App.vue中，使用keep-alive标签包裹router-view，并设置include属性为需要缓存的组件名称，例如：

<template>
  <div id="app">
    <router-view v-slot="{ Component }">
      <keep-alive :include="cachedViews">
        <component :is="Component" />
      </keep-alive>
    </router-view>
  </div>
</template>

<script>
export default {
  name: 'App',
  computed: {
    cachedViews() {
      // 获取需要缓存的组件名称
      return this.$route.matched.filter(route => route.meta.keepAlive).map(route => route.name)
    }
  }
}
</script>

这样就可以实现对二级路由组件的缓存了。