背景

项目需要基于 vue-element-admin 开发，vue-element-admin主要定位是中后台管理系统，而项目又偏向前中台，因此想使用顶部导航栏的方式。原本以为很简单，不就是将 导航栏组件 mode设为 horizontal 就可以了吗，naive~ 排查了一下代码（和官文），发现 ：

这里同时也改造了 element-ui 默认侧边栏不少的样式，所有的 css 都可以在 @/styles/sidebar.scss 中找到，你也可以根据自己的需求进行修改。

问题

在收起侧边栏的时候，顶部导航栏样式出现问题（此处无图，大概就是有子目录的节点标题之间的距离没有了）。

期望的效果

不改变导航栏与路由绑定的效果，把侧边栏变成顶部导航栏。

当然也可以同时保留两种方式：

解决办法

步骤一

@/styles/sidebar.scss 修改.hideSidebar 的样式

  .hideSidebar {
    .sidebar-container {
      width: 0 !important;  //默认54px，收起时会展示图标，因此我们设为0
    }

    .main-container {
      margin-left: 0;  //默认54px，收起时会留出 54px 的空白，因此我们设为0
    }

    .submenu-title-noDropdown {
      padding: 0 !important;
      position: relative;

      .el-tooltip {
        padding: 0 !important;

        .svg-icon {
          margin-left: 20px;
        }
      }
    }
/*    注释掉.hideSidebar的子样式.el-submenu，避免submenu样式失灵，原因很简单，就是这段代码会导致标题之间距离从原本的20px变成0*/
 /*   .el-submenu {
      overflow: hidden;

      &>.el-submenu__title {
        padding: 0 !important;

        .svg-icon {
          margin-left: 20px;
        }

        .el-submenu__icon-arrow {
          display: none;
        }
      }
    }*/
    .el-menu--collapse {
      .el-submenu {
        &>.el-submenu__title {
          &>span {
            height: 0;
            width: 0;
            overflow: hidden;
            visibility: hidden;
            display: inline-block;
          }
        }
      }
    }
  }

步骤二

复制一份@/views/layout/Sidebar 组件，粘贴到相同路径下，更改组件名为HeadNavbar

在index.js中声明组件

@/views/layout/HeadNavbar/index.vue 将template修改如下：

<template>
  <el-menu
    :default-active="activeMenu"
    class="el-menu-demo"
    mode="horizontal"
    background-color="#545c64"
    text-color="#fff"
    active-text-color="#ffd04b">

    <sidebar-item v-for="route in permission_routes" :key="route.path" :item="route" :base-path="route.path" />
    </el-menu>

</template>

@/views/layout/HeadNavbar/SidebarItem.vue 将template修改如下：

<template>
  <!-- style设置为inline-block，避免标题垂直布局-->
  <div v-if="!item.hidden" style="display:inline-block;">
    <template
      v-if="hasOneShowingChild(item.children,item) && (!onlyOneChild.children||onlyOneChild.noShowingChildren)&&!item.alwaysShow">
      <app-link v-if="onlyOneChild.meta" :to="resolvePath(onlyOneChild.path)">
        <el-menu-item :index="resolvePath(onlyOneChild.path)">
          <item :title="onlyOneChild.meta.title"/>
        </el-menu-item>
      </app-link>
    </template>

      <el-submenu v-else ref="subMenu" :index="resolvePath(item.path)" popper-append-to-body >
        <template slot="title" >
          <item v-if="item.meta" :title="item.meta.title"/>
         <!-- 增加固定宽度解决箭头被遮挡的问题-->
          <div style="display: inline-block; width:18px;"></div>
        </template>
        <vertical-item
          v-for="child in item.children"
          :key="child.path"
          :is-nest="true"
          :item="child"
          :base-path="resolvePath(child.path)"
        />
      </el-submenu>

  </div>
</template>

@/views/layout/HeadNavbar/VerticalItem.vue 顶部导航栏不需要显示图标，将template修改如下：

<template>
  <div v-if="!item.hidden" >
    <template
      v-if="hasOneShowingChild(item.children,item) && (!onlyOneChild.children||onlyOneChild.noShowingChildren)&&!item.alwaysShow">
      <app-link v-if="onlyOneChild.meta" :to="resolvePath(onlyOneChild.path)">
        <el-menu-item :index="resolvePath(onlyOneChild.path)">
          <item :title="onlyOneChild.meta.title"/>
        </el-menu-item>
      </app-link>
    </template>

      <el-submenu v-else ref="subMenu" :index="resolvePath(item.path)" popper-append-to-body>
        <template slot="title" >
          <item v-if="item.meta" :title="item.meta.title"/>
        </template>
        <vertical-item
          v-for="child in item.children"
          :key="child.path"
          :is-nest="true"
          :item="child"
          :base-path="resolvePath(child.path)"
        />
      </el-submenu>

  </div>
</template>

步骤三

完成以上步骤以后顶部导航栏的组件就改造好了，只需要在index.vue 下引入就可以使用。

<template>
  <div>
    <div :class="classObj" class="app-wrapper">
      <div v-if="device==='mobile'&&sidebar.opened" class="drawer-bg" @click="handleClickOutside"/>
      <sidebar class="sidebar-container"/>
      <div :class="{hasTagsView:needTagsView}" class="main-container">
        <div :class="{'fixed-header':fixedHeader}">
          <navbar/>
          <head-navbar />
          <tags-view v-if="needTagsView"/>
        </div>
        <app-main/>
        <right-panel v-if="showSettings">
          <settings/>
        </right-panel>
      </div>
    </div>
  </div>

</template>
<script>
  import RightPanel from '@/components/RightPanel'
  import {AppMain, Navbar, Settings, Sidebar, TagsView, HeadNavbar} from './components'
  import ResizeMixin from './mixin/ResizeHandler'
  import {mapState} from 'vuex'

  export default {
    name: 'Layout',
    components: {
      AppMain,
      Navbar,
      HeadNavbar,
      RightPanel,
      Settings,
      Sidebar,
      TagsView
    },
    ~~~~~~~~~~

其他

这里我对Navbar.vue 进行了简单的改造，将relative布局改为flex布局，便于后期加工。附上代码，就不解释了：

<template>
  <div class="navbar">
    <hamburger id="hamburger-container" :is-active="sidebar.opened" class="hamburger-container" @toggleClick="toggleSideBar" />
    <div class="title">产品全寿命周期服务平台</div>
    <!--<breadcrumb id="breadcrumb-container" class="breadcrumb-container" />-->
    <div class="right-menu">
      <template v-if="device!=='mobile'">
        <search id="header-search" class="right-menu-item" />

        <error-log class="errLog-container right-menu-item hover-effect" />

        <screenfull id="screenfull" class="right-menu-item hover-effect" />

        <el-tooltip content="Global Size" effect="dark" placement="bottom">
          <size-select id="size-select" class="right-menu-item hover-effect" />
        </el-tooltip>

      </template>

      <el-dropdown class="avatar-container right-menu-item hover-effect" trigger="click">
        <div class="avatar-wrapper">
          <img :src="avatar+'?imageView2/1/w/80/h/80'" class="user-avatar">
          <i class="el-icon-caret-bottom" />
        </div>
        <el-dropdown-menu slot="dropdown">
          <router-link to="/profile/index">
            <el-dropdown-item>Profile</el-dropdown-item>
          </router-link>
          <router-link to="/">
            <el-dropdown-item>Dashboard</el-dropdown-item>
          </router-link>
          <a target="_blank" href="https://github.com/PanJiaChen/vue-element-admin/">
            <el-dropdown-item>Github</el-dropdown-item>
          </a>
          <a target="_blank" href="https://panjiachen.github.io/vue-element-admin-site/#/">
            <el-dropdown-item>Docs</el-dropdown-item>
          </a>
          <el-dropdown-item divided>
            <span style="display:block;" @click="logout">Log Out</span>
          </el-dropdown-item>
        </el-dropdown-menu>
      </el-dropdown>
    </div>
  </div>
</template>

<script>
import { mapGetters } from 'vuex'
import Breadcrumb from '@/components/Breadcrumb'
import Hamburger from '@/components/Hamburger'
import ErrorLog from '@/components/ErrorLog'
import Screenfull from '@/components/Screenfull'
import SizeSelect from '@/components/SizeSelect'
import Search from '@/components/HeaderSearch'

export default {
  components: {
    Breadcrumb,
    Hamburger,
    ErrorLog,
    Screenfull,
    SizeSelect,
    Search
  },
  computed: {
    ...mapGetters([
      'sidebar',
      'avatar',
      'device'
    ])
  },
  methods: {
    toggleSideBar() {
      this.$store.dispatch('app/toggleSideBar')
    },
    async logout() {
      await this.$store.dispatch('user/logout')
      this.$router.push(`/login?redirect=${this.$route.fullPath}`)
    }
  }
}
</script>

<style lang="scss" scoped>
.navbar {
  height: 100px;
  overflow: hidden;
  // position: relative;
  display: flex;
  flex-direction: row;
  justify-content:space-between;
  background: #fff;
  box-shadow: 0 1px 4px rgba(0, 21, 41, .08);
}


  .hamburger-container {

    line-height: 100px;
    height: 100%;
    width:50px;
    flex:0 0 auto;
    float: left;
    cursor: pointer;
    transition: background .3s;
    -webkit-tap-highlight-color:transparent;

    &:hover {
      background: rgba(0, 0, 0, .025)
    }
  }
.title{
  line-height: 100px;
  font-size:40px;
  margin-left:20px;
  width:500px;
  flex:0 0 auto;

}

  .breadcrumb-container {
    float: left;
  }

  .errLog-container {
    display: inline-block;
    vertical-align: top;
  }

  .right-menu {
    flex:1 1 auto;
    float: right;
    height: 100%;
    line-height: 100px;
    display:flex;
    flex-direction:row;
    justify-content: flex-end;

    &:focus {
      outline: none;
    }

    .right-menu-item {
      display: inline-block;
      padding: 0 10px;
      height: 100%;
      font-size: 18px;
      color: #5a5e66;
      vertical-align: text-bottom;

      &.hover-effect {
        cursor: pointer;
        transition: background .3s;

        &:hover {
          background: rgba(0, 0, 0, .025)
        }
      }
    }

    .avatar-container {
      margin-right: 30px;

      .avatar-wrapper {
        margin-top: 10px;
        position: relative;

        .user-avatar {
          cursor: pointer;
          width: 40px;
          height: 40px;
          border-radius: 10px;
        }

        .el-icon-caret-bottom {
          cursor: pointer;
          position: absolute;
          right: -20px;
          top: 25px;
          font-size: 12px;
        }
      }
    }
  }

</style>