第六章：react-router4

6.1. 相关理解

6.1.1. react-router 的理解

react 的一个插件库
专门用来实现一个 SPA 应用
基于 react 的项目基本都会用到此库

6.1.2. SPA 的理解

单页 Web 应用（single page web application，SPA）
整个应用只有一个完整的页面
点击页面中的链接不会刷新页面, 本身也不会向服务器发请求
当点击路由链接时, 只会做页面的局部更新
数据都需要通过 ajax 请求获取, 并在前端异步展现

6.1.3. 路由的理解

什么是路由?

a. 一个路由就是一个映射关系(key:value)

b. key 为路由路径, value 可能是 function/component

路由分类

a. 后台路由: node 服务器端路由, value 是 function, 用来处理客户端提交的请求并返回一个响应数据

b. 前台路由: 浏览器端路由, value 是 component, 当请求的是路由 path 时, 浏览器端前没有发送 http 请求, 但界面会更新显示对应的组件

后台路由

a. 注册路由: router.get(path, function(req, res))

b. 当 node 接收到一个请求时, 根据请求路径找到匹配的路由, 调用路由中的函数来
处理请求, 返回响应数据

前端路由

a. 注册路由: <Route path="/about" component={About}>

b. 当浏览器的 hash 变为#about 时, 当前路由组件就会变为 About 组件

6.1.4. 前端路由的实现

history 库

a. 网址: https://github.com/ReactTraining/history

b. 管理浏览器会话历史(history)的工具库

c. 包装的是原生 BOM 中 window.history 和 window.location.hash

history API

a. History.createBrowserHistory(): 得到封装 window.history 的管理对象

b. History.createHashHistory(): 得到封装 window.location.hash 的管理对象

c. history.push(): 添加一个新的历史记录

d. history.replace(): 用一个新的历史记录替换当前的记录

e. history.goBack(): 回退到上一个历史记录

f. history.goForword(): 前进到下一个历史记录

g. history.listen(function(location){}): 监视历史记录的变化

测试

<!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8"><title>history test</title></head><body><p><input type="text"></p><a href="/test1" onclick="return push('/test1')">test1</a><br><br><button onClick="push('/test2')">push test2</button><br><br><button onClick="back()">回退</button><br><br><button onClick="forword()">前进</button><br><br><button onClick="replace('/test3')">replace test3</button><br><br><script type="text/javascript"src="https://cdn.bootcss.com/history/4.7.2/history.js"></script><script type="text/javascript">let history = History.createBrowserHistory() // 方式一// history = History.createHashHistory() // 方式二// console.log(history)function push (to) {history.push(to)return false}function back() {history.goBack()}function forword() {history.goForward()}function replace (to) {history.replace(to)}history.listen((location) => {console.log(' 请求路由路径变化了', location)})</script></body>
</html>

6.2. react-router 相关 API

6.2.1. 组件

<BrowserRouter>
<HashRouter>
<Route>
<Redirect>
<Link>
<NavLink>
<Switch>

6.2.2. 其它

history 对象
match 对象
withRouter 函数

6.3. 基本路由使用

6.3.1. 效果

6.3.2. 准备

下载 react-router: npm install --save react-router@4
引入 bootstrap.css: <link rel="stylesheet" href="/css/bootstrap.css">

6.3.3. 路由组件: views/about.jsx

import React from 'react'
export default function About() {return <div>About 组件内容</div>
}

6.3.4. 路由组件: views/home.jsx

import React from 'react'
export default function About() {return <div>Home 组件内容</div>
}

6.3.5. 包装 NavLink 组件: components/my-nav-link.jsx

import React from 'react'
import {NavLink} from 'react-router-dom'
export default function MyNavLink(props) {return <NavLink {...this.props} activeClassName='activeClass'/>
}

6.3.6. 应用组件: components/app.jsx

import React from 'react'
import {Route, Switch, Redirect} from 'react-router-dom'
import MyNavLink from './components/my-nav-link'
import About from './views/about'
import Home from './views/home'
export default class App extends React.Component {render () {return (<div><div className="row"><div className="col-xs-offset-2 col-xs-8"><div className="page-header"><h2>React Router Demo</h2></div></div></div><div className="row"><div className="col-xs-2 col-xs-offset-2"><div className="list-group">{/* 导航路由链接 */}<MyNavLink className="list-group-item" to='/about' >About</MyNavLink><MyNavLink className="list-group-item" to='/home'>Home</MyNavLink></div></div><div className="col-xs-6"><div className="panel"><div className="panel-body">{/* 可切换的路由组件 */}<Switch><Route path='/about' component={About} /><Route path='/home' component={Home} /><Redirect to='/about' /></Switch></div></div></div></div></div>)}
}

6.3.7. 自定义样式: index.css

.activeClass {color: red !important;
}

6.3.8. 入口 JS: index.js

import React from 'react'
import ReactDOM from 'react-dom'
import {BrowserRouter, HashRouter} from 'react-router-dom'
import App from './components/app'
import './index.css'
ReactDOM.render((<BrowserRouter><App /></BrowserRouter>/*<HashRouter>
<App />
</HashRouter>*/),document.getElementById('root')
)

6.4. 嵌套路由使用

6.4.1. 效果

6.4.2. 二级路由组件: views/news.jsx

import React from 'react'
export default class News extends React.Component {state = {newsArr: ['news001', 'news002', 'news003']}
render () {return (<div><ul>{this.state.newsArr.map((news, index) => <li key={index}>{news}</li>)}</ul></div>)
}
}

6.4.3. 二级路由组件: views/message.jsx

import React from 'react'
import {Link, Route} from 'react-router-dom'
export default class Message extends React.Component {state = {messages: []}componentDidMount () {// 模拟发送 ajax 请求setTimeout(() => {const data = [{id: 1, title: 'Message001'},{id: 3, title: 'Message003'},{id: 6, title: 'Message006'},]this.setState({messages: data})}, 1000)}render () {const path = this.props.match.pathreturn (<div><ul>{this.state.messages.map((m, index) => {return (<li key={index}><Link to='???'>{m.title}</Link></li>)})}</ul></div>)}
}

6.4.4. 一级路由组件: views/home.jsx

import React from 'react'
import {Switch, Route, Redirect} from 'react-router-dom'
import MyNavLink from './components/my-nav-link'
import News from './views/news'
import Message from './views/message'
export default function Home() {return (<div><h2>Home 组件内容</h2><div><ul className="nav nav-tabs"><li><MyNavLink to='/home/news'>News</MyNavLink></li><li><MyNavLink to="/home/message">Message</MyNavLink></li></ul><Switch><Route path='/home/news' component={News} /><Route path='/home/message' component={Message} /><Redirect to='/home/news'/></Switch></div></div>)
}

6.5. 向路由组件传递参数数据

6.5.1. 效果

6.5.2. 三级路由组件: views/message-detail.jsx

import React from 'react'
const messageDetails = [{id: 1, title: 'Message001', content: ' 我爱你,  中国'},{id: 3, title: 'Message003', content: ' 我爱你,  老婆'},{id: 6, title: 'Message006', content: ' 我爱你,  孩子'},
]
export default function MessageDetail(props) {const id = props.match.params.idconst md = messageDetails.find(md => md.id===id*1)return (<ul><li>ID: {md.id}</li><li>TITLE: {md.title}</li><li>CONTENT: {md.content}</li></ul>)
}

6.5.3. 二级路由组件: views/message.jsx

import React from 'react'
import {Link, Route} from 'react-router-dom'
import MessageDetail from "./views/message-detail"
export default class Message extends React.Component {state = {messages: []}componentDidMount () {// 模拟发送 ajax 请求setTimeout(() => {const data = [{id: 1, title: 'Message001'},{id: 3, title: 'Message003'},{id: 6, title: 'Message006'},]this.setState({messages: data})}, 1000)}render () {const path = this.props.match.pathreturn (<div><ul>{this.state.messages.map((m, index) => {return (<li key={index}><Link to={`${path}/${m.id}`}>{m.title}</Link></li>)})}</ul><hr/><Route path={`${path}/:id`} component={MessageDetail}></Route></div>)}
}

6.6. 多种路由跳转方式

6.6.1. 效果

6.6.2. 二级路由: views/message.jsx

import React from 'react'
import {Link, Route} from 'react-router-dom'
import MessageDetail from "./views/message-detail"
export default class Message extends React.Component {state = {messages: []}componentDidMount () {// 模拟发送 ajax 请求setTimeout(() => {const data = [{id: 1, title: 'Message001'},{id: 3, title: 'Message003'},{id: 6, title: 'Message006'},]this.setState({messages: data})}, 1000)}ShowDetail = (id) => {this.props.history.push(`/home/message/${id}`)}ShowDetail2 = (id) => {this.props.history.replace(`/home/message/${id}`)}back = () => {this.props.history.goBack()}forward = () => {this.props.history.goForward()}render () {const path = this.props.match.pathreturn (<div><ul>{this.state.messages.map((m, index) => {return (<li key={index}><Link to={`${path}/${m.id}`}>{m.title}</Link>&nbsp;<button onClick={() => this.ShowDetail(m.id)}>查看详情(push)</button>&nbsp;<button onClick={() => this.ShowDetail2(m.id)}>查看详情(replace)</button></li>)})}</ul><p><button onClick={this.back}>返回</button>&nbsp;<button onClick={this.forward}>前进</button>&nbsp;</p><hr/><Route path={`${path}/:id`} component={MessageDetail}></Route></div>)}
}