react react-redux学习记录

1.原理

UI组件:不能使用任何redux的api，只负责页面的呈现、交互等。
容器组件：负责和redux通信，将结果交给UI组件。看得出来容器组件很重要的，它连接着ui组件和redux

2.怎么用呢

文件目录结构：

2.1 容器组件

import CountUI from '../../components/Count';//引入action
import {createIncrementAction,createSubtractionAction,createIncrementAsyncAction
} from '../../redux/count_action'//connect的第一个第一个参数主要可传两个参数，相当于将store中的状态和操作状态传递给UI组件
import { connect } from 'react-redux';/* 1.mapStateToProps函数返回的是一个对象；2.返回的对象中的key就作为传递给UI组件props的key,value就作为传递给UI组件props的value3.mapStateToProps用于传递状态
*/
function mapStateToProps(state){return {count:state}
}/* 1.mapDispatchToProps函数返回的是一个对象；2.返回的对象中的key就作为传递给UI组件props的key,value就作为传递给UI组件props的value3.mapDispatchToProps用于传递操作状态的方法
*/
function mapDispatchToProps(dispatch){return {jia:number => dispatch(createIncrementAction(number)),jian:number => dispatch(createSubtractionAction(number)),jiaAsync:(number,time) => dispatch(createIncrementAsyncAction(number,time)),}
} //使用connect()()创建并暴露一个Count的容器组件
export default connect(mapStateToProps,mapDispatchToProps)(CountUI)

2.2UI组件

import React, { Component } from "react";
import store from "../../redux/store";export default class Count extends Component {state = { carName: "奔驰c63" };componentDidMount() {store.subscribe(() => {this.setState({});});}//加法increment = () => {const { value } = this.selectNumber;this.props.jia(value*1)};//减法decrement = () => {const { value } = this.selectNumber;this.props.jian(value*1,500)};//奇数再加incrementIfOdd = () => {const { value } = this.selectNumber;if (this.props.count % 2 !== 0) {this.props.jia(value*1)}};//异步加incrementAsync = () => {const { value } = this.selectNumber;this.props.jiaAsync(value*1,500)};render() {console.log('UI组件接收到的props是',this.props);return (<div><h1>当前求和为：{this.props.count}</h1><select ref={(c) => (this.selectNumber = c)}><option value="1">1</option><option value="2">2</option><option value="3">3</option></select>&nbsp;<button onClick={this.increment}>+</button>&nbsp;<button onClick={this.decrement}>-</button>&nbsp;<button onClick={this.incrementIfOdd}>当前求和为奇数再加</button>&nbsp;<button onClick={this.incrementAsync}>异步加</button>&nbsp;</div>);}
}

2.3 App.jsx

import React, { Component } from 'react'
import Count from './containers/Count'
import store from './redux/store'export default class App extends Component {render() {return (<div><Count  store={store}/></div>)}
}

3.简化

3.1简写mapDispatch

export default connect(mapStateToProps, {//和之前的箭头函数都是返回的一个action对象,react-redux优化了自动分发dispatchjia: createIncrementAction,jian: createSubtractionAction,jiaAsync: createIncrementAsyncAction,
})(CountUI);

3.2 Provider组件的使用

不使用react-redux的话，需要在在index.js写上对redux的监听

//这是react18.0之前的版本写法
store.subscrible(() =>{
ReactDOM.render(<App/>,document.getElementById("root"))
})

使用react-redux的话，不需要监听的了；而且在App.jsx中:

如果有很多的容器组件，那就需要写很多重复的store={store},优化是当前页面：

然后再index.js中使用Provider组件

3.3整合UI组件和容器组件

直接将UI组件和容器组件整合成一个

import React, { Component } from "react";//引入action
import {createIncrementAction,createSubtractionAction,createIncrementAsyncAction,
} from "../../redux/count_action";//connect的第一个第一个参数主要可传两个参数，相当于将store中的状态和操作状态传递给UI组件
import { connect } from "react-redux";export  class Count extends Component {state = { carName: "奔驰c63" };//加法increment = () => {const { value } = this.selectNumber;this.props.jia(value*1)};//减法decrement = () => {const { value } = this.selectNumber;this.props.jian(value*1,500)};//奇数再加incrementIfOdd = () => {const { value } = this.selectNumber;if (this.props.count % 2 !== 0) {this.props.jia(value*1)}};//异步加incrementAsync = () => {const { value } = this.selectNumber;this.props.jiaAsync(value*1,500)};render() {console.log('UI组件接收到的props是',this.props);return (<div><h1>当前求和为：{this.props.count}</h1><select ref={(c) => (this.selectNumber = c)}><option value="1">1</option><option value="2">2</option><option value="3">3</option></select>&nbsp;<button onClick={this.increment}>+</button>&nbsp;<button onClick={this.decrement}>-</button>&nbsp;<button onClick={this.incrementIfOdd}>当前求和为奇数再加</button>&nbsp;<button onClick={this.incrementAsync}>异步加</button>&nbsp;</div>);}
}/* 1.mapStateToProps函数返回的是一个对象；2.返回的对象中的key就作为传递给UI组件props的key,value就作为传递给UI组件props的value3.mapStateToProps用于传递状态
*/
function mapStateToProps(state) {return { count: state };
}/* 1.mapDispatchToProps函数返回的是一个对象；2.返回的对象中的key就作为传递给UI组件props的key,value就作为传递给UI组件props的value3.mapDispatchToProps用于传递操作状态的方法
*/
// function mapDispatchToProps(dispatch){
// 	return {
// 		jia:createIncrementAction,
// 		jian:createSubtractionAction,
// 		jiaAsync:createIncrementAsyncAction,
// 	}
// }//使用connect()()创建并暴露一个Count的容器组件
export default connect(mapStateToProps, {//和之前的箭头函数都是返回的一个action对象,react-redux优化了自动分发dispatchjia: createIncrementAction,jian: createSubtractionAction,jiaAsync: createIncrementAsyncAction,
})(Count);