Vue路由Hash模式分析

2023-09-12 18:02| 来源: 网络整理| 查看: 265

Vue路由Hash模式分析

Vue-router是Vue的核心组件，主要是作为Vue的路由管理器，Vue-router默认hash模式，即使用URL的Hash来模拟一个完整的URL，当URL改变时页面不会重新加载。

描述

Hash符号即#原本的目的是用来指示URL中指示网页中的位置，例如https://www.example.com/index.html#print即代表example的index.html的print位置，浏览器读取这个URL后，会自动将print位置滚动至可视区域，通常使用标签的name属性或者标签的id属性指定锚点。通过window.location.hash属性能够读取锚点位置，可以为Hash的改变添加hashchange监听事件，每一次改变Hash，都会在浏览器的访问历史中增加一个记录，此外Hash虽然出现在URL中，但不会被包括在HTTP请求中，即#及之后的字符不会被发送到服务端进行资源或数据的请求，其是用来指导浏览器动作的，对服务器端没有效果，因此改变Hash不会重新加载页面。 Vue-router的作用就是通过改变URL，在不重新请求页面的情况下，更新页面视图，从而动态加载与销毁组件，简单的说就是，虽然地址栏的地址改变了，但是并不是一个全新的页面，而是之前的页面某些部分进行了修改，这也是SPA单页应用的特点，其所有的活动局限于一个Web页面中，非懒加载的页面仅在该Web页面初始化时加载相应的HTML、JavaScript、CSS文件，一旦页面加载完成，SPA不会进行页面的重新加载或跳转，而是利用JavaScript动态的变换HTML，默认Hash模式是通过锚点实现路由以及控制组件的显示与隐藏来实现类似于页面跳转的交互。

分析

Vue-router源码的实现比较复杂，会处理各种兼容问题与异常以及各种条件分支，文章分析比较核心的代码部分，精简过后的版本，重要部分做出注释，commit id为560d11d。

首先是在定义Router时调用Vue.use(VueRouter)，此时会调用VueRouter类上的静态方法，即VueRouter.install = install，install模块主要是保证Vue-router只被use一次，以及通过mixin在Vue的生命周期beforeCreate内注册实例，在destroyed内销毁实例，还有定义$router与$route属性为只读属性以及与全局组件的注册。

// dev/src/install.js line 6 export function install (Vue) { if (install.installed && _Vue === Vue) return install.installed = true // 保证 Vue-router 只被 use 一次 _Vue = Vue const isDef = v => v !== undefined const registerInstance = (vm, callVal) => { let i = vm.$options._parentVnode if (isDef(i) && isDef(i = i.data) && isDef(i = i.registerRouteInstance)) { i(vm, callVal) } } Vue.mixin({ beforeCreate () { // 注册实例 if (isDef(this.$options.router)) { // this.$options.router 来自于 VueRouter 的实例化 // 判断实例是否已经挂载 this._routerRoot = this this._router = this.$options.router this._router.init(this) // // 调用 VueRouter 的 init 方法 Vue.util.defineReactive(this, '_route', this._router.history.current) } else { this._routerRoot = (this.$parent && this.$parent._routerRoot) || this // 将组件的 _routerRoot 都指向根 Vue 实例 } registerInstance(this, this) }, destroyed () { // 销毁实例即挂载undefined registerInstance(this) } }) Object.defineProperty(Vue.prototype, '$router', { get () { return this._routerRoot._router } }) Object.defineProperty(Vue.prototype, '$route', { get () { return this._routerRoot._route } }) Vue.component('RouterView', View) // 注册全局组件 Vue.component('RouterLink', Link) // 注册全局组件 const strats = Vue.config.optionMergeStrategies // use the same hook merging strategy for route hooks strats.beforeRouteEnter = strats.beforeRouteLeave = strats.beforeRouteUpdate = strats.created }

之后是VueRouter对象的构造函数，主要是先获取mode的值，如果mode的值为history但是浏览器不支持history模式,那么就强制设置mode值为hash，接下来根据mode的值，来选择vue-router使用哪种模式。

// dev/src/index.js line 40 constructor (options: RouterOptions = {}) { this.app = null this.apps = [] this.options = options this.beforeHooks = [] this.resolveHooks = [] this.afterHooks = [] this.matcher = createMatcher(options.routes || [], this) // 创建路由匹配对象 let mode = options.mode || 'hash' this.fallback = mode === 'history' && !supportsPushState && options.fallback !== false // 检车兼容 if (this.fallback) { mode = 'hash' } if (!inBrowser) { mode = 'abstract' } this.mode = mode switch (mode) { case 'history': this.history = new HTML5History(this, options.base) break case 'hash': this.history = new HashHistory(this, options.base, this.fallback) // 实例化Hash模式 break case 'abstract': this.history = new AbstractHistory(this, options.base) break default: if (process.env.NODE_ENV !== 'production') { assert(false, `invalid mode: ${mode}`) } } }

在构造函数中调用了创建路由匹配对象的方法createMatcher，而在createMatcher中又调用了实际用以创建路由映射表的方法createRouteMap，可以说createMatcher函数的作用就是创建路由映射表，然后通过闭包的方式让addRoutes和match函数能够使用路由映射表的几个对象，最后返回一个Matcher对象。

// dev/src/create-matcher.js line 16 export function createMatcher ( routes: Array, router: VueRouter ): Matcher { const { pathList, pathMap, nameMap } = createRouteMap(routes) // 创建路由映射表 function addRoutes (routes) { createRouteMap(routes, pathList, pathMap, nameMap) } function match ( // 路由匹配 raw: RawLocation, currentRoute?: Route, redirectedFrom?: Location ): Route { const location = normalizeLocation(raw, currentRoute, false, router) // location 是一个对象，类似于 {"_normalized":true,"path":"/","query":{},"hash":""} const { name } = location if (name) { // 如果有路由名称就进行nameMap映射 const record = nameMap[name] // nameMap[name] = 路由记录 if (process.env.NODE_ENV !== 'production') { warn(record, `Route with name '${name}' does not exist`) } if (!record) return _createRoute(null, location) const paramNames = record.regex.keys .filter(key => !key.optional) .map(key => key.name) if (typeof location.params !== 'object') { location.params = {} } if (currentRoute && typeof currentRoute.params === 'object') { for (const key in currentRoute.params) { if (!(key in location.params) && paramNames.indexOf(key) > -1) { location.params[key] = currentRoute.params[key] } } } location.path = fillParams(record.path, location.params, `named route "${name}"`) return _createRoute(record, location, redirectedFrom) } else if (location.path) { // 如果路由配置了path，到pathList和PathMap里匹配到路由记录 location.params = {} for (let i = 0; i < pathList.length; i++) { const path = pathList[i] const record = pathMap[path] if (matchRoute(record.regex, location.path, location.params)) { return _createRoute(record, location, redirectedFrom) } } } // no match return _createRoute(null, location) } function redirect ( // 处理重定向 record: RouteRecord, location: Location ): Route { const originalRedirect = record.redirect let redirect = typeof originalRedirect === 'function' ? originalRedirect(createRoute(record, location, null, router)) : originalRedirect if (typeof redirect === 'string') { redirect = { path: redirect } } if (!redirect || typeof redirect !== 'object') { if (process.env.NODE_ENV !== 'production') { warn( false, `invalid redirect option: ${JSON.stringify(redirect)}` ) } return _createRoute(null, location) } const re: Object = redirect const { name, path } = re let { query, hash, params } = location query = re.hasOwnProperty('query') ? re.query : query hash = re.hasOwnProperty('hash') ? re.hash : hash params = re.hasOwnProperty('params') ? re.params : params if (name) { // resolved named direct const targetRecord = nameMap[name] if (process.env.NODE_ENV !== 'production') { assert(targetRecord, `redirect failed: named route "${name}" not found.`) } return match({ _normalized: true, name, query, hash, params }, undefined, location) } else if (path) { // 1. resolve relative redirect const rawPath = resolveRecordPath(path, record) // 2. resolve params const resolvedPath = fillParams(rawPath, params, `redirect route with path "${rawPath}"`) // 3. rematch with existing query and hash return match({ _normalized: true, path: resolvedPath, query, hash }, undefined, location) } else { if (process.env.NODE_ENV !== 'production') { warn(false, `invalid redirect option: ${JSON.stringify(redirect)}`) } return _createRoute(null, location) } } function alias ( // 处理别名 record: RouteRecord, location: Location, matchAs: string ): Route { const aliasedPath = fillParams(matchAs, location.params, `aliased route with path "${matchAs}"`) const aliasedMatch = match({ _normalized: true, path: aliasedPath }) if (aliasedMatch) { const matched = aliasedMatch.matched const aliasedRecord = matched[matched.length - 1] location.params = aliasedMatch.params return _createRoute(aliasedRecord, location) } return _createRoute(null, location) } function _createRoute ( // 创建路由 record: ?RouteRecord, location: Location, redirectedFrom?: Location ): Route { if (record && record.redirect) { return redirect(record, redirectedFrom || location) } if (record && record.matchAs) { return alias(record, location, record.matchAs) } return createRoute(record, location, redirectedFrom, router) // 创建路由对象 } return { match, addRoutes } } // dev/src/create-route-map.js line 7 export function createRouteMap ( routes: Array, oldPathList?: Array, oldPathMap?: Dictionary, oldNameMap?: Dictionary ): { pathList: Array, pathMap: Dictionary, nameMap: Dictionary } { // the path list is used to control path matching priority const pathList: Array = oldPathList || [] // 创建映射表 // $flow-disable-line const pathMap: Dictionary = oldPathMap || Object.create(null) // $flow-disable-line const nameMap: Dictionary = oldNameMap || Object.create(null) routes.forEach(route => { // 遍历路由配置，为每个配置添加路由记录 addRouteRecord(pathList, pathMap, nameMap, route) }) // ensure wildcard routes are always at the end for (let i = 0, l = pathList.length; i < l; i++) { // 确保通配符在最后 if (pathList[i] === '*') { pathList.push(pathList.splice(i, 1)[0]) l-- i-- } } if (process.env.NODE_ENV === 'development') { // warn if routes do not include leading slashes const found = pathList // check for missing leading slash .filter(path => path && path.charAt(0) !== '*' && path.charAt(0) !== '/') if (found.length > 0) { const pathNames = found.map(path => `- ${path}`).join('\n') warn(false, `Non-nested routes must include a leading slash character. Fix the following routes: \n${pathNames}`) } } return { pathList, pathMap, nameMap } } function addRouteRecord ( // 添加路由记录 pathList: Array, pathMap: Dictionary, nameMap: Dictionary, route: RouteConfig, parent?: RouteRecord, matchAs?: string ) { const { path, name } = route // 获得路由配置下的属性 if (process.env.NODE_ENV !== 'production') { assert(path != null, `"path" is required in a route configuration.`) assert( typeof route.component !== 'string', `route config "component" for path: ${String( path || name )} cannot be a ` + `string id. Use an actual component instead.` ) } const pathToRegexpOptions: PathToRegexpOptions = route.pathToRegexpOptions || {} const normalizedPath = normalizePath(path, parent, pathToRegexpOptions.strict) if (typeof route.caseSensitive === 'boolean') { pathToRegexpOptions.sensitive = route.caseSensitive } const record: RouteRecord = { // 生成记录对象 path: normalizedPath, regex: compileRouteRegex(normalizedPath, pathToRegexpOptions), components: route.components || { default: route.component }, instances: {}, name, parent, matchAs, redirect: route.redirect, beforeEnter: route.beforeEnter, meta: route.meta || {}, props: route.props == null ? {} : route.components ? route.props : { default: route.props } } if (route.children) { // Warn if route is named, does not redirect and has a default child route. // If users navigate to this route by name, the default child will // not be rendered (GH Issue #629) if (process.env.NODE_ENV !== 'production') { if ( route.name && !route.redirect && route.children.some(child => /^\/?$/.test(child.path)) ) { warn( false, `Named Route '${route.name}' has a default child route. ` + `When navigating to this named route (:to="{name: '${ route.name }'"), ` + `the default child route will not be rendered. Remove the name from ` + `this route and use the name of the default child route for named ` + `links instead.` ) } } route.children.forEach(child => { // 递归路由配置的 children 属性，添加路由记录 const childMatchAs = matchAs ? cleanPath(`${matchAs}/${child.path}`) : undefined addRouteRecord(pathList, pathMap, nameMap, child, record, childMatchAs) }) } if (!pathMap[record.path]) { // 如果有多个相同的路径，只有第一个起作用，后面的会被忽略 pathList.push(record.path) pathMap[record.path] = record } if (route.alias !== undefined) { // 如果路由有别名的话，给别名也添加路由记录 const aliases = Array.isArray(route.alias) ? route.alias : [route.alias] for (let i = 0; i < aliases.length; ++i) { const alias = aliases[i] if (process.env.NODE_ENV !== 'production' && alias === path) { warn( false, `Found an alias with the same value as the path: "${path}". You have to remove that alias. It will be ignored in development.` ) // skip in dev to make it work continue } const aliasRoute = { path: alias, children: route.children } addRouteRecord( pathList, pathMap, nameMap, aliasRoute, parent, record.path || '/' // matchAs ) } } if (name) { if (!nameMap[name]) { nameMap[name] = record } else if (process.env.NODE_ENV !== 'production' && !matchAs) { warn( false, `Duplicate named routes definition: ` + `{ name: "${name}", path: "${record.path}" }` ) } } }

在上文的构造函数中实例化的HashHistory对象就是对于Hash模式下的路由的处理，主要是通过继承History对象以及自身实现的方法完成路由，以及针对于不支持history api的兼容处理，以及保证默认进入的时候对应的Hash值是以/开头的，如果不是则替换。在初始化VueRouter时调用的init方法调用了路由切换以及调用了setupListeners方法实现了路由的切换的监听回调，注意此时并没有在HashHistory对象的构造函数中直接添加事件监听，这是为了修复vuejs/vue-router#725的问题，简要来说就是说如果在beforeEnter这样的钩子函数中是异步的话，beforeEnter钩子就会被触发两次，原因是因为在初始化的时候如果此时的hash值不是以/开头的话就会补上#/，这个过程会触发hashchange事件，所以会再走一次生命周期钩子，也就意味着会再次调用beforeEnter钩子函数。

// dev/src/index.js line 21 export default class VueRouter { //... init (app: any /* Vue component instance */) { process.env.NODE_ENV !== 'production' && assert( install.installed, `not installed. Make sure to call \`Vue.use(VueRouter)\` ` + `before creating root instance.` ) this.apps.push(app) // set up app destroyed handler // https://github.com/vuejs/vue-router/issues/2639 app.$once('hook:destroyed', () => { // clean out app from this.apps array once destroyed const index = this.apps.indexOf(app) if (index > -1) this.apps.splice(index, 1) // ensure we still have a main app or null if no apps // we do not release the router so it can be reused if (this.app === app) this.app = this.apps[0] || null if (!this.app) this.history.teardown() }) // main app previously initialized // return as we don't need to set up new history listener if (this.app) { return } this.app = app const history = this.history if (history instanceof HTML5History || history instanceof HashHistory) { const handleInitialScroll = routeOrError => { const from = history.current const expectScroll = this.options.scrollBehavior const supportsScroll = supportsPushState && expectScroll if (supportsScroll && 'fullPath' in routeOrError) { handleScroll(this, routeOrError, from, false) } } const setupListeners = routeOrError => { history.setupListeners() // 初始化添加事件监听 handleInitialScroll(routeOrError) } history.transitionTo( // 如果默认页，需要根据当前浏览器地址栏里的 path 或者 hash 来激活对应的路由 history.getCurrentLocation(), setupListeners, setupListeners ) } history.listen(route => { this.apps.forEach(app => { app._route = route }) }) } //... } // dev/src/history/base.js line 24 export class History { // ... transitionTo ( location: RawLocation, onComplete?: Function, onAbort?: Function ) { let route // catch redirect option https://github.com/vuejs/vue-router/issues/3201 try { route = this.router.match(location, this.current) // // 获取匹配的路由信息 } catch (e) { this.errorCbs.forEach(cb => { cb(e) }) // Exception should still be thrown throw e } const prev = this.current this.confirmTransition( // 确认跳转 route, () => { this.updateRoute(route) // 更新当前 route 对象 onComplete && onComplete(route) this.ensureURL() // 子类实现的更新url地址对于 hash 模式的话就是更新 hash 的值 this.router.afterHooks.forEach(hook => { hook && hook(route, prev) }) // fire ready cbs once if (!this.ready) { this.ready = true this.readyCbs.forEach(cb => { cb(route) }) } }, err => { if (onAbort) { onAbort(err) } if (err && !this.ready) { // Initial redirection should not mark the history as ready yet // because it's triggered by the redirection instead // https://github.com/vuejs/vue-router/issues/3225 // https://github.com/vuejs/vue-router/issues/3331 if (!isNavigationFailure(err, NavigationFailureType.redirected) || prev !== START) { this.ready = true this.readyErrorCbs.forEach(cb => { cb(err) }) } } } ) } confirmTransition (route: Route, onComplete: Function, onAbort?: Function) { const current = this.current this.pending = route const abort = err => { // changed after adding errors with // https://github.com/vuejs/vue-router/pull/3047 before that change, // redirect and aborted navigation would produce an err == null if (!isNavigationFailure(err) && isError(err)) { if (this.errorCbs.length) { this.errorCbs.forEach(cb => { cb(err) }) } else { warn(false, 'uncaught error during route navigation:') console.error(err) } } onAbort && onAbort(err) } const lastRouteIndex = route.matched.length - 1 const lastCurrentIndex = current.matched.length - 1 if ( isSameRoute(route, current) && // 如果是相同的路由就不跳转 // in the case the route map has been dynamically appended to lastRouteIndex === lastCurrentIndex && route.matched[lastRouteIndex] === current.matched[lastCurrentIndex] ) { this.ensureURL() return abort(createNavigationDuplicatedError(current, route)) } const { updated, deactivated, activated } = resolveQueue( // 通过对比路由解析出可复用的组件，需要渲染的组件，失活的组件 this.current.matched, route.matched ) const queue: Array

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Vue路由Hash模式分析

Vue路由Hash模式分析

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