React(8)

千锋学习视频https://www.bilibili.com/video/BV1dP4y1c7qd?p=72&spm_id_from=pageDriver&vd_source=f07a5c4baae42e64ab4bebdd9f3cd1b3

1.React 路由

1.1 什么是路由？

        路由是根据不同的 url 地址展示不同的内容或页面。 

        一个针对React而设计的路由解决方案、可以友好的帮你解决React components 到URl之间的同步映射关系。

1.2 路由安装

npm i react-router-dom@5

1.3 路由使用

import React, { Component } from 'react'
import {HashRouter,Route} from 'react-router-dom'
import Film from './views/Film'
import Cinemas from './views/Cinemas'
import Center from './views/Center'



export default class componentName extends Component {
    render() {
        return (
            

                   
                    
                    
                    
                 
            
        )
    }
}

   会让路径带上一个/#

也可以把路由封装成一个组件抽离出去

import React, { Component } from 'react'

import MyRouter from './MyRouter'
// import Film from './views/Film'
// import Cinemas from './views/Cinemas'
// import Center from './views/Center'



export default class componentName extends Component {
    render() {
        return (
            

                {/*   也可以把路由封装成一个组件抽离出去
                    
                    
                    
                 */}
                
        
            
        )
    }
}

import React, { Component } from 'react'
import {HashRouter,Route} from 'react-router-dom'
import Film from './views/Film'
import Cinemas from './views/Cinemas'
import Center from './views/Center'

export default class MyRouter extends Component {
    render() {
        return (
            

                   
                    
                    
                    
                
            
        )
    }
}

1.4 路由重定向

如果没有匹配的路径，需要跳转到指定的路径  使用

import React, { Component } from 'react'
import {HashRouter,Route,Redirect,Switch} from 'react-router-dom'
import Film from './views/Film'
import Cinemas from './views/Cinemas'
import Center from './views/Center'

export default class MyRouter extends Component {
    render() {
        return (
            

                   
                    
                    
                    
                    {/* 匹配/路径的时候 模糊匹配  跳转到/films */}
                    
                    
                
            
        )
    }
}

 但是这个做法存在问题：当输入http://localhost:3000/#/center 会跳到center 但再次刷新又会跳到/films 

改进：使用Switch   匹配一次后将不再继续匹配

import React, { Component } from 'react'
import { HashRouter, Route, Redirect, Switch } from 'react-router-dom'
import Film from './views/Film'
import Cinemas from './views/Cinemas'
import Center from './views/Center'

export default class MyRouter extends Component {
    render() {
        return (
            

                
                    
                        
                        
                        
                        {/* 匹配/路径的时候  跳转到/films */}
                        
                    
                
            
        )
    }
}

精准匹配exact

场景：/ 跳转到/films  其他不匹配上述路由的跳转到404

import React, { Component } from 'react'
import { HashRouter, Route, Redirect, Switch } from 'react-router-dom'
import Film from './views/Film'
import Cinemas from './views/Cinemas'
import Center from './views/Center'
import NotFound from './views/NotFound'

export default class MyRouter extends Component {
    render() {
        return (
            

                
                    
                        
                        
                        
                        {/* 匹配/路径的时候  跳转到/films */}
                        
                        
                        
                    
                
            
        )
    }
}

import React, { Component } from 'react'

export default class NotFound extends Component {
    render() {
        return (
            

                404 Not Found
            
        )
    }
}

注意：exact 精确匹配 (Redirect 即使使用了exact, 外面还要嵌套Switch 来用)

1.5 嵌套路由

MyRouter组件中的路由保持不变   当/film模糊匹配到后会进入Film组件

以下代码在Film组件中写即可

1.6 路由跳转方式

1.声明式导航

 

import React, { Component } from 'react'
import {NavLink} from 'react-router-dom'

export default class Navbar extends Component {
    render() {
        return (
            

                
电影
                
影院
                
我的

            
        )
    }
}

意思是可以监听到地址  如果是/center会给我的这个a标签给加上class="active"的属性，

也可以自定义属性，方便设置css高亮显示

  
电影
  
影院
  
我的

2.编程式导航

this.props.history.push(`/center`)

或者导入useHistory

import {useHistory} from 'react-router-dom'

const history =useHistory()

history.push(`/detail`)