Vue中router-view无法显示的解决办法

//App.vue中
<template>
  <div id="app">
//关键是 router-view 能否成功渲染
    <router-view></router-view>
    <div>
      <p>
        If Element is successfully added to this project, you'll see an
        <code v-text="'<el-button>'"></code>
        below
      </p>
      <el-button>el-button</el-button>
    </div>
  </div>
</template>
<script>
export default {
  name: 'app',
  components: {
  }
}
</script>

//index.js文件
 
import Vue from 'vue'
import VueRouter from 'vue-router'
import HomeView from '../views/main/HomeView.vue'
import Layout from '../views/LayoutView.vue'
 
Vue.use(VueRouter)
 
//1.这里是routes，指定路径和成员 
const routes = [
  {
    path: '/',
    name: 'Layout',
    
    //以下的 component（这是对的） 千万注意，不要写成 components（这是错的）
    component: Layout,
    children: [
      {
        path: '',
        name: 'Home',
        component: HomeView,
        meta: {
          isLogin: true
        }
      },
      {
        path: 'params',
        name: 'params',
        component: () => import('../views/main/ParamsView.vue'),
        meta: {
          isLogin: true
        }
      },
      {
        path: 'ad',
        name: 'ADclassify',
        component: () => import('../views/main/ADClassify.vue'),
        meta: {
          isLogin: true
        }
      },
      {
        path: 'product',
        name: 'product',
        component: () => import('../views/main/ProductView.vue'),
        meta: {
          isLogin: true
        }
      }
    ]
  },
  {
    path: '/login',
    name: 'Login',
    component: () => import('../views/LoginView.vue'),
    meta: {
      isLogin: true
    }
  }
]
//2.这里是router,是一个VueRouter对象
const router = new VueRouter({
  mode: 'history',
  base: process.env.BASE_URL,
  routes
//3.这里是routes,对应1中指定的内容
})
 
export default router

//main.js
import Vue from 'vue'
import App from './App.vue'
import router from './router'
import store from './store'
import './plugins/element.js'
import './assets/css/common.css'
//导入了这个文件，之后就看不见 router-view 渲染的内容了
// import './router/permission.js'
Vue.config.productionTip = false
new Vue({
  router,
  store,
  render: h => h(App)
}).$mount('#app')

//permission.js
import router from './index'
 
router.beforeEach((to, from, next) => {
  if (to.meta.isLogin) {
    const token = false
    if (token) {
      next()
    } else {
      next({
        name: 'Login'
      })
    }
  } else {
    next()
  }
})