react-redux及redux状态管理工具使用详解
作者:weixin_43993776
Redux是为javascript应用程序提供一个状态管理工具集中的管理react中多个组件的状态redux是专门作状态管理的js库(不是react插件库可以用在其他js框架中例如vue,但是基本用在react中),这篇文章主要介绍了react-redux及redux状态管理工具使用详解,需要的朋友可以参考下
react-redux使用及原理
1、下载 react-redux redux redux-thunk三个依赖包
yarn add react-redux redux redux-thunk
2、配置store对象,用来管理全局状态
import { createStore, combineReducers, applyMiddleware } from "redux" // redux-thunk中间件,用来处理异步传值的方法 import reduxThunk from "redux-thunk" import Reducer1 from "./reducer/Reducer1" import Reducer2 from "./reducer/Reducer2" import Reducer3 from "./reducer/Reducer3" // combineReducers方法用来合并reducer,将reducer分开,便于管理 const reducer = combineReducers({ Reducer1, Reducer2, Reducer3, }) // 创建store对象,并将其暴露出去 const store = createStore( reducer, applyMiddleware(reduxThunk) ) export default store
3、创建reducer.js文件, reducer文件主要是用来处理改变store状态里面的值
const reducer1 = (prevState = { num: 10 }, action) => { let newState = { ...prevState } switch(action.type) { case "TYPE1": newState.num = action.value return newState default: return prevState } } export default reducer1
4、在入口文件index.js中引入provider,并包裹在App根组件外,其中的store就是创建的store对象
import React from 'react'; import ReactDOM from 'react-dom/client'; import { Provider } from "react-redux" import App from './studyReactRedux/App'; import "./static/main.css" import store from "./studyReactRedux/reactRedux/index"; const root = ReactDOM.createRoot(document.getElementById('root')); root.render( <Provider store = { store }> <App></App> </Provider> )
至此在react所有的组件中都有了store对象,方便存取全局状态了
接下来就是在组件中存值取值了
1、在组件中取值
<div> {props.num} </div> const matStateToProps = (state) => { return { num: state.Reducer1.num } } export default connect(matStateToProps, mapDispatchToProps)(Home)
2、组件中存值(同步)
const handleClick = (val) => { props.changeVal(val) } <button onClick={ () => handleClick('同步传过去的值') }>同步存值</button> const mapDispatchToProps = { changeVal(val) { return { type: 'TYPE1', value: val } } } export default connect(matStateToProps, mapDispatchToProps)(Home)
3、组件中存值(异步)
const handleClick = (val) => { props.changeVal(val) } <button onClick={ () => handleClick('同步传过去的值') }>同步存值</button> const mapDispatchToProps = { changeVal(val) { return (dispatch) => { setTimeout(()=> { dispatch({ type: 'TYPE1', value: val }) }, 300) } } } export default connect(matStateToProps, mapDispatchToProps)(Home)
react-redux持久化
// 持久化可以自己在存状态的时候自己往local session里面存值,借助redux-persist库 // 1、下载redux-persist yarn add redux-persist // 2、修改 store文件 /** * * react-redux的使用步骤 * * 1、引入react-redux 和 redux 和 redux-thunk * * 2、index.js中引入 import { Provider } from "react-redux" * * 3、在根组件中App外面包上一层 <Provider store={ store }></Provider>, 其中store就是redux中创建的store对象 * * 4、在组件中使用connect( (state)=>{ * return { state: state.xxxReducer.xxx } * } )(App) * 其中的 connect 是从 react-redux 中解构出来的 import { connect } from "react-redux" * connect函数中有两个参数: 第一个是从store状态中取值的,第二个是dispatch传值的 * * 详细见home中的child1给child2传值, child2给child1传值 */ import { createStore, combineReducers, applyMiddleware } from "redux" import reduxThunk from "redux-thunk" import {persistStore, persistReducer} from 'redux-persist' import storage from 'redux-persist/lib/storage' import Reducer1 from "./reducer/Reducer1" import Reducer2 from "./reducer/Reducer2" import Reducer3 from "./reducer/Reducer3" const persistConfig = { key: 'item', storage, whitelist: ['Reducer1'] // 表示只持久化 Reducer1的值 blacklist: ['Reducer2'] 表示不持久化Reducer2 } const reducer = combineReducers({ Reducer1, Reducer2, Reducer3, }) const myPersistReducer = persistReducer(persistConfig, reducer) const store = createStore(myPersistReducer, applyMiddleware(reduxThunk)) const persistor = persistStore(store) export { store, persistor } // 3、修改入口文件 index.js import React from 'react'; import ReactDOM from 'react-dom/client'; import { Provider } from "react-redux" import App from './studyReactRedux/App'; import "./static/main.css" import { store, persistor } from "./studyReactRedux/reactRedux/index"; import {PersistGate} from 'redux-persist/integration/react' import { HashRouter } from "react-router-dom" const root = ReactDOM.createRoot(document.getElementById('root')); root.render( <Provider store = { store }> <PersistGate loading={null} persistor={persistor}> <HashRouter> <App></App> </HashRouter> </PersistGate> </Provider> )
不管是同步改状态还是异步改状态,只要dispatch就会发布action动作到store对象中,store交给reducer来处理修改响应的状态,从而达到了解耦的效果
redux的使用详解
redux是原生js实现的,和react没有直接的关系,使用起来相对react-redux稍微麻烦点,需要使用人员自己动手进行消息订阅和取消订阅
配置store对象和react-redux一样,见上面配置文件,只是不需要在App根组件中注入provider供应商
在使用的过程中不太一样,没有connect高阶组件
1、组件中取值
// 其中的store就是引入的store对象 const [val, setVal] = useState(store.getState().Reducer1.num) // 取store中的初始值 useEffect(()=>{ // 订阅消息,当store中的值发生改变的时候就会走到此方法里面来 const unsubscibe = store.subscribe(() => { setVal(store.getState().Reducer1.num) }) return() => { // 取消订阅 unsubscibe() } }, []) <div>{val}</div>
2、组件中存值(同步)
handleClick(val) { store.dispatch({ type: 'TYPE1', value: val }) }
3、组件中存值(异步)
handleClick(val) { store.dispatch((dispatch) => { dispatch({ type: 'TYPE1', value: val }) }) }
到此这篇关于react-redux以及redux状态管理工具详解的文章就介绍到这了,更多相关react-redux状态管理内容请搜索脚本之家以前的文章或继续浏览下面的相关文章希望大家以后多多支持脚本之家!