1、目标效果

        源码地址：multipal-layout-demo: vue2实现多布局+暗黑模式

默认布局：头部宽度100%，侧边栏、内容区

顶部布局：头部宽度100%，内容区

侧边栏布局：侧边栏高度100%，头部、内容区

2、原理分析

（1）vuex文件

import Vue from 'vue'
import Vuex from 'vuex'Vue.use(Vuex)export default new Vuex.Store({state: {// 暗黑模式isDark: false,// 布局类型layoutType: 'default'},mutations: {// 修改暗黑模式set_is_dark(state, val) {state.isDark = val},// 修改布局类型set_layout_type(state, val) {state.layoutType = val}},actions: {},modules: {}
})

        

（2）布局缩略图如何实现？用div + css 手动实现布局样式

        父组件传递一个布局类型数组，遍历此组件；用一个变量保存索引值，点击不同的布局类型项时切换索引并在vuex修改当前选中的布局类型

        将缩略图封装成组件：Thumbnail.vue

<template><!-- 缩略图 --><div class="thumbnail"><div class="layout" v-for="(item, index) in layouts" @click="changeCheck(item, index)"><template v-if="item.type == 'default'"><div class="top" :style="{ background: isDark ? 'black' : '#fff' }"></div><div class="left" :style="{ background: isDark ? 'black' : '#fff' }"></div></template><template v-if="item.type == 'top'"><div class="top" :style="{ background: isDark ? 'black' : '#fff' }"></div></template><template v-if="item.type == 'slide'"><div class="top"></div><div class="left" :style="{ background: isDark ? 'black' : '#fff' }"></div></template><i class="el-icon-check" v-show="checked == index"></i></div></div>
</template><script>
import { mapState } from 'vuex'
export default {props: {// 布局类型数组layouts: {type: Array,default: () => []}},data() {return {// 当前选中值checked: 0,}},computed: {// 获取是否是暗黑模式，从而缩略图实现暗黑效果...mapState(['isDark'])},methods: {// 切换选中值changeCheck(item, index) {this.checked = indexthis.$store.commit('set_layout_type', item.type)}}
}
</script><style lang="less" scoped>
.thumbnail {display: flex;width: 100%;.layout {position: relative;width: 50px;height: 50px;border: 1px solid gray;overflow: hidden;background: #f0f0f0;border-radius: 5px;cursor: pointer;.top {position: absolute;left: 0;top: 0;width: 100%;height: 25%;}.left {position: absolute;left: 0;top: 0;bottom: 0;width: 25%;height: 100%;}.el-icon-check {position: absolute;left: 50%;top: 50%;transform: translate(-50%, -50%);font-size: 20px;}}
}
</style>

（3）建立多个不同类型的布局文件： 

 

 侧边栏布局 ：src/views/layout/SlideLayout.vue

<template><!-- 侧边栏布局 --><div><Sliderbar></Sliderbar><Header></Header><div class="content-box"><router-view /></div></div>
</template><script>
import Sliderbar from '@/components/Sliderbar.vue'
import Header from '@/components/Header.vue'
export default {components: {Header,Sliderbar,},
}
</script><style lang="less" scoped></style>

默认布局布局：src/views/layout/DefaultLayout.vue 

<template><!-- 默认布局 --><div><Header></Header><Sliderbar></Sliderbar><div class="content-box"><router-view /></div></div>
</template><script>
import Header from '@/components/Header.vue'
import Sliderbar from '@/components/Sliderbar.vue'
export default {components: { Header, Sliderbar },
}
</script><style lang="less" scoped></style>

顶部布局：src/views/layout/TopLayout.vue 

<template><!-- 顶栏布局 --><div><Header></Header><div class="content-box"><router-view /></div></div>
</template><script>
import Header from '@/components/Header.vue'
export default {components: {Header,},
}
</script><style lang="less" scoped></style>

  

 （4）首页组件 Home.vue，Home.vue下面渲染二级路由 

 

<template><!-- vuex获取选中的布局类型 --><div><defaultLayout v-show="layoutType == 'default'"></defaultLayout><slideLayout v-show="layoutType == 'slide'"></slideLayout><topLayout v-show="layoutType == 'top'"></topLayout></div>
</template><script>
import defaultLayout from './layout/DefaultLayout.vue'
import slideLayout from './layout/SlideLayout.vue'
import topLayout from './layout/TopLayout.vue'
import { mapState } from 'vuex'export default {components: { defaultLayout, slideLayout, topLayout },computed: {...mapState(['layoutType'])},
}
</script><style lang="less" scoped></style>

 （5）暗黑模式、布局类型变量都是保存在vuex中，因为多个组件之间进行数据通信比较方便！通过mapState取出vuex数据，然后通过computed接受mapState值，但如果想要直接修改mapState中的值则会报以下的错误：

         computed property "isDark" was assigned to but it has no setter.

        这是因为computed为只读的。不能直接修改computed的数据，要想修改则使用set

  computed: {...mapState(['isDark']),// computed property "isDark" was assigned to but it has no setter.  这是因为computed为只读的。不能直接修改computed的数据，要想修改则使用setdarkMode: {get() {return this.isDark},set(val) {this.$store.commit('set_is_dark', val)// 获取html根元素标签let html = document.documentElementif (val) {// html添加class="dark"选择器html.classList.add('dark')} else {// html移除class="dark"选择器html.classList.remove('dark')}}}},