Vue--keep-alive使用實(shí)例詳解

更新時(shí)間：2022年08月24日 09:09:55 作者：IT利刃出鞘

這篇文章主要介紹了Vue--keep-alive使用實(shí)例詳解,keep-alive標(biāo)簽主要用于保留組件狀態(tài)或避免重新渲染，用示例代碼介紹Vue的keep-alive的用法，需要的朋友可以參考下

簡(jiǎn)介

說明

本文用示例介紹Vue的keep-alive的用法。

keep-alive標(biāo)簽主要用于保留組件狀態(tài)或避免重新渲染。

官網(wǎng)網(wǎng)址

https://v2.cn.vuejs.org/v2/api/#keep-alive

相關(guān)網(wǎng)址

vue2中的keep-alive使用總結(jié)及注意事項(xiàng)

公共代碼

路由（router/index.js）

import Vue from 'vue'
import VueRouter from 'vue-router'
import Parent from '../components/Parent'
 
Vue.use(VueRouter)
 
const routes = [
  {
    path: '/',
    name: 'Parent',
    component: Parent
  }
 
]
 
const router = new VueRouter({
  routes
})
 
export default router

生命周期mixin（mixins/LifeCycle.js）

下邊的兩個(gè)頁面組件都要打印生命周期，所以我把它抽出作為mixin。

export default {
  computed: {
    name () {
      return this.$options.name
    }
  },
  created () {
    console.log('created ==> ' + this.name)
  },
  activated () {
    console.log('activated ==> ' + this.name)
  },
  deactivated () {
    console.log('deactivated ==> ' + this.name)
  },
  destroyed () {
    console.log('destroyed ==> ' + this.name)
  }
}

子頁面組件

components/CompA.vue

<template>
  <div class="outer">
    <div>
      這是CompA
    </div>
  </div>
</template>
 
<script>
import LifeCycle from '../mixins/LifeCycle'
 
export default {
  name: 'CompA',
  mixins: [LifeCycle]
}
</script>
 
<style scoped>
.outer {
  margin: 20px;
  border: 2px solid blue;
  padding: 20px;
}
</style>

components/CompB.vue

<template>
  <div class="outer">
    這是CompB
  </div>
</template>
 
<script>
import LifeCycle from '../mixins/LifeCycle'
 
export default {
  name: 'CompB',
  mixins: [LifeCycle]
}
</script>
 
<style scoped>
.outer {
  margin: 20px;
  border: 2px solid blue;
  padding: 20px;
}
</style>

動(dòng)態(tài)組件實(shí)例

不加keep-alive

代碼

components/Parent.vue

<template>
  <div class="outer">
    <div>
      這是Parent
    </div>
    <br>
    <button @click="useCompA">切換到CompA</button>
    |
    <button @click="useCompB">切換到CompB</button>
    <component :is="componentName"></component>
  </div>
</template>
 
<script>
import CompA from './CompA'
import CompB from './CompB'
 
export default {
  name: 'Parent',
  components: {
    CompA,
    CompB
  },
  data () {
    return {
      componentName: ''
    }
  },
  methods: {
    useCompA () {
      this.componentName = 'CompA'
    },
    useCompB () {
      this.componentName = 'CompB'
    }
  }
}
</script>
 
<style scoped>
.outer {
  margin: 20px;
  border: 2px solid red;
  padding: 20px;
}
</style>

測(cè)試

訪問：http://localhost:8080/#/

可以發(fā)現(xiàn)：進(jìn)入組件時(shí)調(diào)用created；離開組件時(shí)調(diào)用destroyed。

加keep-alive

代碼

component/Parent.vue

將動(dòng)態(tài)組件用keep-alive標(biāo)簽包起來。

<template>
  <div class="outer">
    <div>
      這是Parent
    </div>
    <br>
    <button @click="useCompA">切換到CompA</button>
    |
    <button @click="useCompB">切換到CompB</button>
    <keep-alive>
      <component :is="componentName"></component>
    </keep-alive>
  </div>
</template>
 
<script>
import CompA from './CompA'
import CompB from './CompB'
 
export default {
  name: 'Parent',
  components: {
    CompA,
    CompB
  },
  data () {
    return {
      componentName: ''
    }
  },
  methods: {
    useCompA () {
      this.componentName = 'CompA'
    },
    useCompB () {
      this.componentName = 'CompB'
    }
  }
}
</script>
 
<style scoped>
.outer {
  margin: 20px;
  border: 2px solid red;
  padding: 20px;
}
</style>

測(cè)試

訪問：http://localhost:8080/#/

可以發(fā)現(xiàn)：進(jìn)入組件時(shí)調(diào)用created、activated；離開組件時(shí)調(diào)用deactivated（不調(diào)用destroyed）。

router-view實(shí)例

不加keep-alive

代碼

修改路由設(shè)置（router/index.js）

import Vue from 'vue'
import VueRouter from 'vue-router'
import Parent from '../components/Parent'
import CompA from '../components/CompA'
import CompB from '../components/CompB'
 
Vue.use(VueRouter)
 
const routes = [
  {
    path: '/',
    name: 'Parent',
    component: Parent
  },
  {
    path: '/compA',
    name: 'CompA',
    component: CompA
  },
  {
    path: '/compB',
    name: 'CompB',
    component: CompB
  }
]
 
const router = new VueRouter({
  routes
})
 
export default router

修改入口組件（components/Parent.vue）

<template>
  <div class="outer">
    <div>
      這是Parent
    </div>
    <br>
    <router-link :to="{name: 'CompA'}">跳轉(zhuǎn)到CompA</router-link> 
    |
    <router-link :to="{name: 'CompB'}">跳轉(zhuǎn)到CompB</router-link>
    <router-view></router-view>
  </div>
</template>
 
<script>
 
export default {
  name: 'Parent'
}
</script>
 
<style scoped>
.outer {
  margin: 20px;
  border: 2px solid red;
  padding: 20px;
}
</style>

測(cè)試

訪問：http://localhost:8080/#/

可以發(fā)現(xiàn)：進(jìn)入路由組件時(shí)調(diào)用created；離開路由組件時(shí)調(diào)用destroyed。

加keep-alive（加到App.vue里）

修改App.vue

將router-view標(biāo)簽包裹在keep-alive標(biāo)簽里。

<template>
  <div id="app">
    <div id="nav">
      <router-link to="/">Home</router-link>
      |
      <router-link to="/about">About</router-link>
    </div>
    <!-- 原來寫法 -->
    <!-- <router-view/> -->
    <keep-alive>
      <router-view/>
    </keep-alive>
  </div>
</template>
 
<style>
<!-- 省略 -->
</style>

測(cè)試

訪問：http://localhost:8080/#/

可以發(fā)現(xiàn)：進(jìn)入組件時(shí)調(diào)用created、activated；離開組件時(shí)調(diào)用deactivated（不調(diào)用destroyed）。

加keep-alive（加到Parent.vue里）

說明

需要做如下兩步：

Parent.vue：將router-view包裹在keep-alive里邊
將CompA和CompB的路由作為Parent的嵌套路由（Children）

如果只修改Parent.vue，將router-view包裹在keep-alive里邊，這樣是沒用的，跟沒有加keep-alive效果一樣。

代碼

修改components/Parent.vue

<template>
  <div class="outer">
    <div>
      這是Parent
    </div>
    <br>
    <router-link :to="{name: 'CompA'}">跳轉(zhuǎn)到CompA</router-link>
    |
    <router-link :to="{name: 'CompB'}">跳轉(zhuǎn)到CompB</router-link>
    <keep-alive>
      <router-view></router-view>
    </keep-alive>
  </div>
</template>
 
<script>
 
export default {
  name: 'Parent'
}
</script>
 
<style scoped>
.outer {
  margin: 20px;
  border: 2px solid red;
  padding: 20px;
}
</style>

修改路由（router/index.js）

import Vue from 'vue'
import VueRouter from 'vue-router'
import Parent from '../components/Parent'
import CompA from '../components/CompA'
import CompB from '../components/CompB'
 
Vue.use(VueRouter)
 
const routes = [
  {
    path: '/',
    name: 'Parent',
    component: Parent,
    children: [
      {
        path: '/compA',
        name: 'CompA',
        component: CompA
      },
      {
        path: '/compB',
        name: 'CompB',
        component: CompB
      }
    ]
  }
 
]
 
const router = new VueRouter({
  routes
})
 
export default router

測(cè)試

訪問：http://localhost:8080/#/