做个网站得投入多少电子商务网站建设的目标是什么意思
第四章 React ajax
一、理解
1. 前置说明
- React本身只关注于界面, 并不包含发送ajax请求的代码
- 前端应用需要通过ajax请求与后台进行交互(json数据)
- react应用中需要集成第三方ajax库(或自己封装)
2. 常用的ajax请求库
- jQuery: 比较重, 如果需要另外引入不建议使用
- axios: 轻量级, 建议使用
- 封装XmlHttpRequest对象的ajax
- promise风格
- 可以用在浏览器端和node服务器端
二、axios
1. 文档
- https://github.com/axios/axios
2. 相关API
2.1 GET请求
axios.get('/user?ID=12345').then(function (response) {console.log(response.data);}).catch(function (error) {console.log(error);});axios.get('/user', {params: {ID: 12345}}).then(function (response) {console.log(response);}).catch(function (error) {console.log(error);});
2.2 POST请求
axios.post('/user', {firstName: 'Fred',lastName: 'Flintstone'
})
.then(function (response) {
console.log(response);
})
.catch(function (error) {
console.log(error);
});
3. 代码（配置代理）
/* src/App.jsx */
import React, { Component } from 'react'
import axios from 'axios'export default class App extends Component {getStudentData = ()=>{axios.get('http://localhost:3000/api1/students').then(response => {console.log('成功了',response.data);},error => {console.log('失败了',error);})}getCarData = ()=>{axios.get('http://localhost:3000/api2/cars').then(response => {console.log('成功了',response.data);},error => {console.log('失败了',error);})}render() {return (<div><button onClick={this.getStudentData}>点我获取学生数据</button><button onClick={this.getCarData}>点我获取汽车数据</button></div>)}
}
/* src/index.js */
//引入react核心库
import React from 'react'
//引入ReactDOM
import ReactDOM from 'react-dom'
//引入App
import App from './App'ReactDOM.render(<App/>,document.getElementById('root'))
/* src/setupProxy.js */
const proxy = require('http-proxy-middleware')module.exports = function(app){app.use(proxy('/api1',{ //遇见/api1前缀的请求，就会触发该代理配置target:'http://localhost:5000', //请求转发给谁changeOrigin:true,//控制服务器收到的请求头中Host的值pathRewrite:{'^/api1':''} //重写请求路径(必须)}),proxy('/api2',{target:'http://localhost:5001',changeOrigin:true,pathRewrite:{'^/api2':''}}),)
}
3.1 方法一
在package.json中追加如下配置
"proxy":"http://localhost:5000"
- 说明：
- 优点：配置简单，前端请求资源时可以不加任何前缀。
- 缺点：不能配置多个代理。
- 工作方式：上述方式配置代理，当请求了3000不存在的资源时，那么该请求会转发给5000 （优先匹配前端资源）
3.2 方法二
- 第一步：创建代理配置文件
在src下创建配置文件：src/setupProxy.js
- 编写setupProxy.js配置具体代理规则：
const proxy = require('http-proxy-middleware')module.exports = function(app) {app.use(proxy('/api1', { //api1是需要转发的请求(所有带有/api1前缀的请求都会转发给5000)target: 'http://localhost:5000', //配置转发目标地址(能返回数据的服务器地址)changeOrigin: true, //控制服务器接收到的请求头中host字段的值/*changeOrigin设置为true时，服务器收到的请求头中的host为：localhost:5000changeOrigin设置为false时，服务器收到的请求头中的host为：localhost:3000changeOrigin默认值为false，但我们一般将changeOrigin值设为true*/pathRewrite: {'^/api1': ''} //去除请求前缀，保证交给后台服务器的是正常请求地址(必须配置)}),proxy('/api2', { target: 'http://localhost:5001',changeOrigin: true,pathRewrite: {'^/api2': ''}}))
}
- 说明：
- 优点：可以配置多个代理，可以灵活的控制请求是否走代理。
- 缺点：配置繁琐，前端请求资源时必须加前缀。
三、案例 – github用户搜索
1. 效果
- 请求地址: https://api.github.com/search/users?q=xxxxxx
2. 代码实现
2.1 静态页面
/* public/css/bootstrap.css */
...
<!-- public/index.html -->
<!DOCTYPE html>
<html lang="en"><head><meta charset="utf-8" /><link rel="icon" href="%PUBLIC_URL%/favicon.ico" /><meta name="viewport" content="width=device-width, initial-scale=1" /><meta name="theme-color" content="#000000" /><metaname="description"content="Web site created using create-react-app"/><link rel="apple-touch-icon" href="%PUBLIC_URL%/logo192.png" /><link rel="manifest" href="%PUBLIC_URL%/manifest.json" /><link rel="stylesheet" href="./css/bootstrap.css"><title>React App</title></head><body><div id="root"></div></body>
</html>
/* src/App.css */
.album {min-height: 50rem; /* Can be removed; just added for demo purposes */padding-top: 3rem;padding-bottom: 3rem;background-color: #f7f7f7;}.card {float: left;width: 33.333%;padding: .75rem;margin-bottom: 2rem;border: 1px solid #efefef;text-align: center;}.card > img {margin-bottom: .75rem;border-radius: 100px;}.card-text {font-size: 85%;}
/* src/App.jsx */
import React, { Component } from 'react'
import './App.css'export default class App extends Component {render() {return (<div className="container"><section className="jumbotron"><h3 className="jumbotron-heading">Search Github Users</h3><div><input type="text" placeholder="enter the name you search"/> <button>Search</button></div></section><div className="row"><div className="card"><a href="https://github.com/reactjs" target="_blank"><img src="https://avatars.githubusercontent.com/u/6412038?v=3" style={{width:'100px'}}/></a><p className="card-text">reactjs</p></div><div className="card"><a href="https://github.com/reactjs" target="_blank"><img src="https://avatars.githubusercontent.com/u/6412038?v=3" style={{width:'100px'}}/></a><p className="card-text">reactjs</p></div><div className="card"><a href="https://github.com/reactjs" target="_blank"><img src="https://avatars.githubusercontent.com/u/6412038?v=3" style={{width:'100px'}}/></a><p className="card-text">reactjs</p></div><div className="card"><a href="https://github.com/reactjs" target="_blank"><img src="https://avatars.githubusercontent.com/u/6412038?v=3" style={{width:'100px'}}/></a><p className="card-text">reactjs</p></div><div className="card"><a href="https://github.com/reactjs" target="_blank"><img src="https://avatars.githubusercontent.com/u/6412038?v=3" style={{width:'100px'}}/></a><p className="card-text">reactjs</p></div></div></div>)}
}
/* src/index.js */
//引入react核心库
import React from 'react'
//引入ReactDOM
import ReactDOM from 'react-dom'
//引入App组件
import App from './App'//渲染App到页面
ReactDOM.render(<App/>,document.getElementById('root'))
2.2 静态组件
2.2.1 List
/* src/components/List/index.jsx */
import React, { Component } from "react";
import "./index.css";export default class List extends Component {render() {return (<div className="row"><div className="card"><a rel="noreferrer" href="https://github.com/reactjs" target="_blank"><imgalt="head_portrait"src="https://avatars.githubusercontent.com/u/6412038?v=3"style={{ width: "100px" }}/></a><p className="card-text">reactjs</p></div><div className="card"><a rel="noreferrer" href="https://github.com/reactjs" target="_blank"><imgalt="head_portrait"src="https://avatars.githubusercontent.com/u/6412038?v=3"style={{ width: "100px" }}/></a><p className="card-text">reactjs</p></div><div className="card"><a rel="noreferrer" href="https://github.com/reactjs" target="_blank"><imgalt="head_portrait"src="https://avatars.githubusercontent.com/u/6412038?v=3"style={{ width: "100px" }}/></a><p className="card-text">reactjs</p></div><div className="card"><a rel="noreferrer" href="https://github.com/reactjs" target="_blank"><imgalt="head_portrait"src="https://avatars.githubusercontent.com/u/6412038?v=3"style={{ width: "100px" }}/></a><p className="card-text">reactjs</p></div><div className="card"><a rel="noreferrer" href="https://github.com/reactjs" target="_blank"><imgalt="head_portrait"src="https://avatars.githubusercontent.com/u/6412038?v=3"style={{ width: "100px" }}/></a><p className="card-text">reactjs</p></div></div>);}
}
/* src/components/List/index.css */
.album {min-height: 50rem; /* Can be removed; just added for demo purposes */padding-top: 3rem;padding-bottom: 3rem;background-color: #f7f7f7;
}.card {float: left;width: 33.333%;padding: 0.75rem;margin-bottom: 2rem;border: 1px solid #efefef;text-align: center;
}.card > img {margin-bottom: 0.75rem;border-radius: 100px;
}.card-text {font-size: 85%;
}
2.2.2 Search
/* src/components/Search/index.jsx */
import React, { Component } from "react";export default class Search extends Component {render() {return (<section className="jumbotron"><h3 className="jumbotron-heading">Search Github Users</h3><div><input type="text" placeholder="enter the name you search" /> <button>Search</button></div></section>);}
}
2.2.3 App
/* src/App.jsx */
import React, { Component } from "react";
import Search from "./components/Search";
import List from "./components/List";export default class App extends Component {render() {return (<div className="container"><Search /><List /></div>);}
}