vue項(xiàng)目中實(shí)現(xiàn)緩存的最佳方案詳解

const express = require('express')
// const bodyParser = require('body-parser')
const app = express()
let allList = Array.from({length: 30}, (v, i) => ({
 id: i,
 name: '視頻' + i,
 isCollect: false
}))
// 后臺(tái)設(shè)置允許跨域訪(fǎng)問(wèn)
// 前后端都是本地localhost，所以不需要設(shè)置cors跨域，如果是部署在服務(wù)器上，則需要設(shè)置
// app.all('*', function (req, res, next) {
// res.header('Access-Control-Allow-Origin', '*')
// res.header('Access-Control-Allow-Headers', 'X-Requested-With')
// res.header('Access-Control-Allow-Methods', 'PUT,POST,GET,DELETE,OPTIONS')
// res.header('X-Powered-By', ' 3.2.1')
// res.header('Content-Type', 'application/json;charset=utf-8')
// next()
// })
app.use(express.json())
app.use(express.urlencoded({extended: false}))
// 1 獲取所有的視頻列表
app.get('/api/getVideoList', function (req, res) {
 let query = req.query
 let currentPage = query.currentPage
 let pageSize = query.pageSize
 let list = allList.slice((currentPage - 1) * pageSize, currentPage * pageSize)
 res.json({
 code: 0,
 data: {
  list,
  total: allList.length
 }
 })
})
// 2 獲取某一條視頻詳情
app.get('/api/getVideoDetail/:id', function (req, res) {
 let id = Number(req.params.id)
 let info = allList.find(v => v.id === id)
 res.json({
 code: 0,
 data: info
 })
})
// 3 收藏或者取消收藏視頻
app.post('/api/collectVideo', function (req, res) {
 let id = Number(req.body.id)
 let isCollect = req.body.isCollect
 allList = allList.map((v, i) => {
 return v.id === id ? {...v, isCollect} : v
 })
 res.json({code: 0})
})
const PORT = 3003
app.listen(PORT, function () {
 console.log('app is listening port' + PORT)
})

import Vue from 'vue'
import Router from 'vue-router'
import home from '../pages/home'
import pageAList from '../pages/pageAList'
import pageADetail from '../pages/pageADetail'
import pageB from '../pages/pageB'
import main from '../pages/main'
Vue.use(Router)

export default new Router({
 routes: [
 {
  path: '/',
  name: 'main',
  component: main,
  redirect: '/home',
  children: [
  {
   path: 'home',
   name: 'home',
   component: home
  },
  {
   path: 'pageAList',
   name: 'pageAList',
   component: pageAList,
   meta: {
   keepAlive: true
   }
  },
  {
   path: 'pageB',
   component: pageB
  }
  ]
 },
 {
  path: '/pageADetail',
  name: 'pageADetail',
  component: pageADetail
 }
 ]
})

const state = {
 excludeComponents: [] 
}
export default state

const mutations = {
 addExcludeComponent (state, excludeComponent) {
 let excludeComponents = state.excludeComponents
 if (Array.isArray(excludeComponent)) {
  state.excludeComponents = [...new Set([...excludeComponents, ...excludeComponent])]
 } else {
  state.excludeComponents = [...new Set([...excludeComponents, excludeComponent])]
 }
 },
 // excludeComponent可能是組件name字符串或者數(shù)組
 removeExcludeComponent (state, excludeComponent) {
 let excludeComponents = state.excludeComponents
 if (Array.isArray(excludeComponent)) {
  for (let i = 0; i < excludeComponent.length; i++) {
  let index = excludeComponents.findIndex(v => v === excludeComponent[i])
  if (index > -1) {
   excludeComponents.splice(index, 1)
  }
  }
 } else {
  for (let i = 0, len = excludeComponents.length; i < len; i++) {
  if (excludeComponents[i] === excludeComponent) {
   excludeComponents.splice(i, 1)
   break
  }
  }
 }
 state.excludeComponents = excludeComponents
 }
}
export default mutations

<template>
 <div id="app">
 <keep-alive :exclude="excludeComponents">
  <router-view v-if="$route.meta.keepAlive"></router-view>
 </keep-alive>
 <router-view v-if="!$route.meta.keepAlive"></router-view>
 </div>
</template>

<script>
export default {
 name: 'App',
 computed: {
 excludeComponents () {
  return this.$store.state.excludeComponents
 }
 }
}
</script

<template>
 <div>
 <ul>
  <li v-for="nav in navs" :key="nav.name">
  <router-link :to="nav.name">{{nav.title}}</router-link>
  </li>
 </ul>
 <keep-alive :exclude="excludeComponents">
  <router-view v-if="$route.meta.keepAlive"></router-view>
 </keep-alive>
 <router-view v-if="!$route.meta.keepAlive"></router-view>
 </div>
</template>
<script>
export default {
 name: 'main.vue',
 data () {
 return {
  navs: [{
  name: 'home',
  title: '首頁(yè)'
  }, {
  name: 'pageAList',
  title: 'pageAList'
  }, {
  name: 'pageB',
  title: 'pageB'
  }]
 }
 },
 methods: {
 },
 computed: {
 excludeComponents () {
  return this.$store.state.excludeComponents
 }
 },
 created () {
 }
}
</script>

import {getVideoList} from '../api'
export default {
 name: 'pageAList', // 組件名稱(chēng)，和組件對(duì)應(yīng)的路由名稱(chēng)不需要相同
 data () {
 return {
  currentPage: 1,
  pageSize: 10,
  total: 0,
  allList: [],
  list: []
 }
 },
 methods: {
 getVideoList () {
  let params = {currentPage: this.currentPage, pageSize: this.pageSize}
  getVideoList(params).then(r => {
  if (r.code === 0) {
   this.list = r.data.list
   this.total = r.data.total
  }
  })
 },
 goIntoVideo (item) {
  this.$router.push({name: 'pageADetail', query: {id: item.id}})
 },
 handleCurrentPage (val) {
  this.currentPage = val
  this.getVideoList()
 }
 },
 beforeRouteEnter (to, from, next) {
 next(vm => {
  vm.$store.commit('removeExcludeComponent', 'pageAList')
  next()
 })
 },
 beforeRouteLeave (to, from, next) {
 let reg = /pageADetail/
 if (reg.test(to.name)) {
  this.$store.commit('removeExcludeComponent', 'pageAList')
 } else {
  this.$store.commit('addExcludeComponent', 'pageAList')
 }
 next()
 },
 activated () {
 this.getVideoList()
 },
 mounted () {
 this.getVideoList()
 }
}

beforeRouteLeave (to, from, next) {
 let componentName = ''
 // 離開(kāi)詳情頁(yè)時(shí),將pageAList添加到exludeComponents里，也就是將需要緩存的頁(yè)面pageAList置為不緩存狀態(tài)
 let list = ['pageAList']
 this.$store.commit('addExcludeComponent', list)
 // 緩存組件路由名稱(chēng)到組件name的映射
 let map = new Map([['pageAList', 'pageAList']])
 componentName = map.get(to.name) || ''
 // 如果離開(kāi)的時(shí)候跳轉(zhuǎn)的路由是pageAList，將pageAList從exludeComponents里面移除，也就是要緩存pageAList
 this.$store.commit('removeExcludeComponent', componentName)
 next()
 }