源码地址

https://github.com/PanJiaChen/vue-element-admin

• 用户登录页面

https://panjiachen.github.io/vue-element-admin/#/login?redirect=/dashboard
源码：
当用户打开https://panjiachen.github.io/vue-element-admin 这个项目的地址时，程序自动在后面加了一个login?redirect=/dashboard，这是怎么加进来的呢？看下面代码第17行

用户访问项目的根目录/时，要进入根目录“/”，这里要看路由里的配置，

router/index.js有一段代码

{
    path: '/',
    component: Layout,
    redirect: '/dashboard',
    children: [
      {
        path: 'dashboard',
        component: () => import('@/views/dashboard/index'),
        name: 'Dashboard',
        meta: { title: 'Dashboard', icon: 'dashboard', affix: true }
      }
    ]
  }

这个组件Layout就是第一个要进入的页面。在进入这个页面时，路由会被下面的路由守卫拦截，

下面是main.js里的代码：

import Vue from 'vue'

import Cookies from 'js-cookie'

import 'normalize.css/normalize.css' // a modern alternative to CSS resets

import Element from 'element-ui'
import './styles/element-variables.scss'

import '@/styles/index.scss' // global css

import App from './App'
import store from './store'
import router from './router'

import './icons' // icon
import './permission' // permission control
import './utils/error-log' // error log

import * as filters from './filters' // global filters

/**
 * If you don't want to use mock-server
 * you want to use MockJs for mock api
 * you can execute: mockXHR()
 *
 * Currently MockJs will be used in the production environment,
 * please remove it before going online ! ! !
 */
if (process.env.NODE_ENV === 'production') {
  const { mockXHR } = require('../mock')
  mockXHR()
}

Vue.use(Element, {
  size: Cookies.get('size') || 'medium' // set element-ui default size
})

// register global utility filters
Object.keys(filters).forEach(key => {
  Vue.filter(key, filters[key])
})

Vue.config.productionTip = false

new Vue({
  el: '#app',
  router,
  store,
  render: h => h(App)
})

上面的代码里第17行引入了一个js文件

import './permission' // permission control

这个文件里的源码中如下：

import router from './router'
import store from './store'
import { Message } from 'element-ui'
import NProgress from 'nprogress' // progress bar
import 'nprogress/nprogress.css' // progress bar style
import { getToken } from '@/utils/auth' // get token from cookie
import getPageTitle from '@/utils/get-page-title'

NProgress.configure({ showSpinner: false }) // NProgress Configuration

const whiteList = ['/login', '/auth-redirect'] // no redirect whitelist

router.beforeEach(async(to, from, next) => {
  // start progress bar
  NProgress.start()

  // set page title
  document.title = getPageTitle(to.meta.title)

  // determine whether the user has logged in
  const hasToken = getToken()

  if (hasToken) {
    if (to.path === '/login') {
      // if is logged in, redirect to the home page
      next({ path: '/' })
      NProgress.done()
    } else {
      // determine whether the user has obtained his permission roles through getInfo
      const hasRoles = store.getters.roles && store.getters.roles.length > 0
      if (hasRoles) {
        next()
      } else {
        try {
          // get user info
          // note: roles must be a object array! such as: ['admin'] or ,['developer','editor']
          const { roles } = await store.dispatch('user/getInfo')

          // generate accessible routes map based on roles
          const accessRoutes = await store.dispatch('permission/generateRoutes', roles)

          // dynamically add accessible routes
          router.addRoutes(accessRoutes)

          // hack method to ensure that addRoutes is complete
          // set the replace: true, so the navigation will not leave a history record
          next({ ...to, replace: true })
        } catch (error) {
          // remove token and go to login page to re-login
          await store.dispatch('user/resetToken')
          Message.error(error || 'Has Error')
          next(`/login?redirect=${to.path}`)
          NProgress.done()
        }
      }
    }
  } else {
    /* has no token*/

    if (whiteList.indexOf(to.path) !== -1) {
      // in the free login whitelist, go directly
      next()
    } else {
      // other pages that do not have permission to access are redirected to the login page.
      next(`/login?redirect=${to.path}`)
      NProgress.done()
    }
  }
})

router.afterEach(() => {
  // finish progress bar
  NProgress.done()
})

引入了路由守卫

router.beforeEach

const hasToken = getToken()

要从cookie里引入token

getToken()方法是从哪里来的呢？

第6行代码显示是从utils/auth文件里来的

import { getToken } from '@/utils/auth'

auth的源码如下：

import Cookies from 'js-cookie'

const TokenKey = 'Admin-Token'

export function getToken() {
  return Cookies.get(TokenKey)
}

export function setToken(token) {
  return Cookies.set(TokenKey, token)
}

export function removeToken() {
  return Cookies.remove(TokenKey)
}

可以看出，auth.js里引入了js-cookie这个包，js-cookie就是从cookie里get和set值
这里比较清楚了。

---

我们回到路由上，/src/permission.js的代码上
如果用户没有token，在代码的第52行

 next(`/login?redirect=${to.path}`)

让用户跳转到login页面，还有一个redirect的参数，值是Layout路由配置中的 redirect: '/dashboard’里的值

请求被转向到login页面，并且带了参数，doashboard就是它的参数
https://panjiachen.github.io/vue-element-admin/#/login?redirect=%2Fdashboard

在login.vue页面里用户点击登录，会进入login.vue
代码如下：

<script>
import { validUsername } from '@/utils/validate'
import SocialSign from './components/SocialSignin'
export default {
  name: 'Login',
  components: { SocialSign },
  data() {
    const validateUsername = (rule, value, callback) => {
      if (!validUsername(value)) {
        callback(new Error('Please enter the correct user name'))
      } else {
        callback()
      }
    }
    const validatePassword = (rule, value, callback) => {
      if (value.length < 6) {
        callback(new Error('The password can not be less than 6 digits'))
      } else {
        callback()
      }
    }
    return {
      loginForm: {
        username: 'admin',
        password: '111111'
      },
      loginRules: {
        username: [{ required: true, trigger: 'blur', validator: validateUsername }],
        password: [{ required: true, trigger: 'blur', validator: validatePassword }]
      },
      passwordType: 'password',
      capsTooltip: false,
      loading: false,
      showDialog: false,
      redirect: undefined,
      otherQuery: {}
    }
  },
  watch: {
    $route: {
      handler: function(route) {
        const query = route.query
        if (query) {
          this.redirect = query.redirect
          this.otherQuery = this.getOtherQuery(query)
        }
      },
      immediate: true
    }
  },
  created() {
    // window.addEventListener('storage', this.afterQRScan)
  },
  mounted() {
    if (this.loginForm.username === '') {
      this.$refs.username.focus()
    } else if (this.loginForm.password === '') {
      this.$refs.password.focus()
    }
  },
  destroyed() {
    // window.removeEventListener('storage', this.afterQRScan)
  },
  methods: {
    checkCapslock(e) {
      const { key } = e
      this.capsTooltip = key && key.length === 1 && (key >= 'A' && key <= 'Z')
    },
    showPwd() {
      if (this.passwordType === 'password') {
        this.passwordType = ''
      } else {
        this.passwordType = 'password'
      }
      this.$nextTick(() => {
        this.$refs.password.focus()
      })
    },
    handleLogin() {
      this.$refs.loginForm.validate(valid => {
        if (valid) {
          this.loading = true
          this.$store.dispatch('user/login', this.loginForm)
            .then(() => {
              this.$router.push({ path: this.redirect || '/', query: this.otherQuery })
              this.loading = false
            })
            .catch(() => {
              this.loading = false
            })
        } else {
          console.log('error submit!!')
          return false
        }
      })
    },
    getOtherQuery(query) {
      return Object.keys(query).reduce((acc, cur) => {
        if (cur !== 'redirect') {
          acc[cur] = query[cur]
        }
        return acc
      }, {})
    }
  }
}
</script>

当用户登录成功 this.$router.push({ path: this.redirect || ‘/’, query: this.otherQuery })，重定向请求到/，还是会带上参数
this.redirect这个变量是在data里定义的一个变量

 redirect: undefined,

初始值为undefined
在watch函数中对修改了变量的值，当url路径发生变化时把，就从query中取出参数，也就是/dashboard这个参数，把参数值赋值给redirect这个变量，就是/dashboard
再把其他的参数取出来，现在没有其他参数了

watch: {
    $route: {
      handler: function(route) {
        const query = route.query
        if (query) {
          this.redirect = query.redirect
          this.otherQuery = this.getOtherQuery(query)
        }
      },
      immediate: true
    }
  }

登录成功，地址转到如下：
https://panjiachen.github.io/vue-element-admin/#/dashboard

实际上是先进入到根目录/，根目录对应的是Layout.vue文件
代码如下：

<template>
  <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 />
        <tags-view v-if="needTagsView" />
      </div>
      <app-main />
      <right-panel v-if="showSettings">
        <settings />
      </right-panel>
    </div>
  </div>
</template>

<script>
import RightPanel from '@/components/RightPanel'
import { AppMain, Navbar, Settings, Sidebar, TagsView } from './components'
import ResizeMixin from './mixin/ResizeHandler'
import { mapState } from 'vuex'
export default {
  name: 'Layout',
  components: {
    AppMain,
    Navbar,
    RightPanel,
    Settings,
    Sidebar,
    TagsView
  },
  mixins: [ResizeMixin],
  computed: {
    ...mapState({
      sidebar: state => state.app.sidebar,
      device: state => state.app.device,
      showSettings: state => state.settings.showSettings,
      needTagsView: state => state.settings.tagsView,
      fixedHeader: state => state.settings.fixedHeader
    }),
    classObj() {
      return {
        hideSidebar: !this.sidebar.opened,
        openSidebar: this.sidebar.opened,
        withoutAnimation: this.sidebar.withoutAnimation,
        mobile: this.device === 'mobile'
      }
    }
  },
  methods: {
    handleClickOutside() {
      this.$store.dispatch('app/closeSideBar', { withoutAnimation: false })
    }
  }
}
</script>

可以看出来，这是一个布局，有sidebar ，和main左右两栏布局
右边是上中下部局
上面是navbar 组件
中间是app-main组件对应的是appMain.vue文件
下面是right-panel，其他它不是在下面呢，是在网页的最右边，像下面这样

点击它就会从右侧出来

这里的重点是 这个组件，
我们找到src/layout/components/AppMain.vue文件

<template>
  <section class="app-main">
    <transition name="fade-transform" mode="out-in">
      <keep-alive :include="cachedViews">
        <router-view :key="key" />
      </keep-alive>
    </transition>
  </section>
</template>

<script>
export default {
  name: 'AppMain',
  computed: {
    cachedViews() {
      return this.$store.state.tagsView.cachedViews
    },
    key() {
      return this.$route.path
    }
  }
}
</script>

可以看到这里又用了一个组件视图，

这个Layout文件还是大有来头的，再来看看它的路由配置

  {
    path: '/',
    component: Layout,
    redirect: '/dashboard',
    children: [
      {
        path: 'dashboard',
        component: () => import('@/views/dashboard/index'),
        name: 'Dashboard',
        meta: { title: 'Dashboard', icon: 'dashboard', affix: true }
      }
    ]
  }

嵌套了好几层，终于在这里看到了
找到了嵌套路由。

/dashboard这个新组件，对应dashboard/index.vue文件，就是嵌套进来的路由
代码如下：

<template>
  <div class="dashboard-container">
    <component :is="currentRole" />
  </div>
</template>

<script>
import { mapGetters } from 'vuex'
import adminDashboard from './admin'
import editorDashboard from './editor'
export default {
  name: 'Dashboard',
  components: { adminDashboard, editorDashboard },
  data() {
    return {
      currentRole: 'adminDashboard'
    }
  },
  computed: {
    ...mapGetters([
      'roles'
    ])
  },
  created() {
    if (!this.roles.includes('admin')) {
      this.currentRole = 'editorDashboard'
    }
  }
}
</script>

这里用到了动态组件
如果不熟悉动态组件，可以参考vuejs的官方文档
动态组件章节：
https://cn.vuejs.org/v2/guide/components-dynamic-async.html
言归正传：
currentRole就是data里定义的adminDashboard
从当前代码里找adminDashboard ，是在dashboard/admin/index.vue里

import adminDashboard from './admin'

完成的代码如下：

<template>
  <div class="dashboard-editor-container">
    <github-corner class="github-corner" />

    <panel-group @handleSetLineChartData="handleSetLineChartData" />

    <el-row style="background:#fff;padding:16px 16px 0;margin-bottom:32px;">
      <line-chart :chart-data="lineChartData" />
    </el-row>

    <el-row :gutter="32">
      <el-col :xs="24" :sm="24" :lg="8">
        <div class="chart-wrapper">
          <raddar-chart />
        </div>
      </el-col>
      <el-col :xs="24" :sm="24" :lg="8">
        <div class="chart-wrapper">
          <pie-chart />
        </div>
      </el-col>
      <el-col :xs="24" :sm="24" :lg="8">
        <div class="chart-wrapper">
          <bar-chart />
        </div>
      </el-col>
    </el-row>

    <el-row :gutter="8">
      <el-col :xs="{span: 24}" :sm="{span: 24}" :md="{span: 24}" :lg="{span: 12}" :xl="{span: 12}" style="padding-right:8px;margin-bottom:30px;">
        <transaction-table />
      </el-col>
      <el-col :xs="{span: 24}" :sm="{span: 12}" :md="{span: 12}" :lg="{span: 6}" :xl="{span: 6}" style="margin-bottom:30px;">
        <todo-list />
      </el-col>
      <el-col :xs="{span: 24}" :sm="{span: 12}" :md="{span: 12}" :lg="{span: 6}" :xl="{span: 6}" style="margin-bottom:30px;">
        <box-card />
      </el-col>
    </el-row>
  </div>
</template>

<script>
import GithubCorner from '@/components/GithubCorner'
import PanelGroup from './components/PanelGroup'
import LineChart from './components/LineChart'
import RaddarChart from './components/RaddarChart'
import PieChart from './components/PieChart'
import BarChart from './components/BarChart'
import TransactionTable from './components/TransactionTable'
import TodoList from './components/TodoList'
import BoxCard from './components/BoxCard'
const lineChartData = {
  newVisitis: {
    expectedData: [100, 120, 161, 134, 105, 160, 165],
    actualData: [120, 82, 91, 154, 162, 140, 145]
  },
  messages: {
    expectedData: [200, 192, 120, 144, 160, 130, 140],
    actualData: [180, 160, 151, 106, 145, 150, 130]
  },
  purchases: {
    expectedData: [80, 100, 121, 104, 105, 90, 100],
    actualData: [120, 90, 100, 138, 142, 130, 130]
  },
  shoppings: {
    expectedData: [130, 140, 141, 142, 145, 150, 160],
    actualData: [120, 82, 91, 154, 162, 140, 130]
  }
}
export default {
  name: 'DashboardAdmin',
  components: {
    GithubCorner,
    PanelGroup,
    LineChart,
    RaddarChart,
    PieChart,
    BarChart,
    TransactionTable,
    TodoList,
    BoxCard
  },
  data() {
    return {
      lineChartData: lineChartData.newVisitis
    }
  },
  methods: {
    handleSetLineChartData(type) {
      this.lineChartData = lineChartData[type]
    }
  }
}
</script>

看看这一堆的报表，正好跟下图能够对应起来