一、Redux 外围
官网是这样解释Redux的：JavaScript 状态容器，提供可预测化的状态治理。
const state = {
modleOpen: "yes",
btnClicked: "no",
btnActiveClass: "active",
page: 5,
size: 10
}- Redux 外围概念及工作流程
- store: 存储状态的容器，JavaScript对象
- View: 视图，HTML页面
- Actions: 对象，形容对状态进行怎么的操作
- Reducers: 函数，操作状态并返回新的状态
-
Redux 计数器案例 ../Redux/src/counter
<body> <button id="plus">+</button> <span id="count">0</span> <button id="minus">-</button> <script src="https://cdn.bootcdn.net/ajax/libs/redux/4.2.0/redux.min.js"></script> <script> // 3 存储默认状态 let initialState = { count: 0 } // 2 创立 reducer 函数 function reducer (state = initialState, action) { // 7 接管 action 并判断 action 的类型 switch (action.type) { case 'increment': return {count : state.count + 1} case 'decrement': return {count : state.count - 1} default: // 初始化是会主动发送一个 init 的 action 用来存储默认的state return state; } } // 1 创立 store 对象, createStore 有第二个参数代表默认值，也就是 reducer 中的 state 参数 let store = Redux.createStore(reducer); // 4 定义 action let increment = { type: 'increment' } let decrement = { type: 'decrement' } // 5 获取按钮并增加事件 document.getElementById('plus').onclick = function() { // 6 触发action store.dispatch(increment); } document.getElementById('minus').onclick = function () { store.dispatch(decrement); } // 8 订阅 store，当store发生变化的时候会执行回调 store.subscribe(() => { // 获取 store 中存储的状态 console.log(store.getState()) document.getElementById('count').innerText = store.getState().count; }); </script> </body> - Redux外围API
const store = Redux.crateStore(reducer): 创立 Store 容器function reducer (state = initialState, action) {}: 创立用于解决状态的 reducer 函数store.getState(): 获取状态store.subscribe(function(){}): 订阅状态store.dispatch({type: 'discription...'}): 触发action
二、React + Redux
1.在 React 中不应用 Redux 时遇到的问题
在 React 中组件通信的数据流是单向的，顶层组件能够通过props属性向上层组件传递数据，而上层组件不能向下层组件传递数据，要实现上层组件批改数据，须要
下层组件传递批改数据办法到上层组件，当我的项目越来越大的时候，组件之间传递数据也就变得越来越艰难。
2.在 React 我的项目中引入 Redux 的益处
应用Redux治理数据，因为Store独立于组件，使得数据管理独立于组件，解决了组件与组件之间传递数据艰难的问题。
3.下载Redux
npm install redux react-redux
4.Redux 工作流程
- 组件通过 dispatch 办法触发 action
- Store 接管 Action 并将 Action 分发给 Reducer
- Reducer 依据 Action 类型对状态进行更改并将更改后的状态返回给Store
- 组件订阅了Store中的状态，Store中的状态更新会同步到组件
5.代码案例
计数器案例 ../Redux/react-redux-guide/src/components/Counter.js
弹出框案例 ../Redux/react-redux-guide/src/components/Modal.js
6.拆分Reducer
../Redux/react-redux-guide/src/react-redux-guide/src/store/reducers/root.reducer.js
三、Redux 中间件
中间件实质上就是一个函数，Redux容许咱们通过中间件的形式，扩大和加强Redux应用程序，加强体现在对action解决能力上，之前的计数器与弹出框案例中。actions都是间接被reducer函数解决的，再退出了中间件当前，在登程了一个action之后这个action会优先被中间件解决，当两头解决完这个action当前，中间件会把这个action传递给reducer，让reducer持续解决
1.开发Redux中间件
开发中间件模版代码，实质上是一个函数，并且是一个柯里化的一个函数
export default store => next => action => {}这个函数中要求咱们返回一个函数，在这个返回的函数中要求咱们再返回一个函数，在最里层的函数中咱们能够执行咱们本人的业务逻辑，在最外层的函数中给咱们提供了一个参数叫store，能够用store.getState获取以后state状态，也能够应用store.dispatch来触发另外一个action，至于干什么具体依据应用的业务逻辑来决定。在最里层的函数也有一个形参，这个形参就是组件触发的action对象，能够依据action.type来决定是否对以后action进行解决。两头的函数也有一个参数，这个参数是一个函数，咱们称之为next，在咱们执行完了逻辑代码之后，咱们要去调用next办法，把以后action 传递给reducer，或者说传递给下一个中间件，因为中间件能够有多个。中间件开发好之后须要引入咱们写的中间件并且注册给redux。
2.注册中间件
中间件在开发实现当前只有被注册能力在Redux的工作流程中失效。
import { createStore, applyMiddleware } from 'redux'
import logger from './middlewares/logger'
createStore(reducer, applyMiddleware(
logger
))代码案例：src/react-redux-guide/src/store/middleware
/**
* src/react-redux-guide/src/store/middleware/logger.js
* 开发中间件
* 中间件模板代码 export default store => next => action => {}
*/
export default store => next => action => {
console.log(action);
console.log(store);
next(action); // 只有调用了next办法才能够将action传递给下一个中间件或者reducer
}/**
* src/react-redux-guide/src/index.js
*/
import { createStore, applyMiddleware } from 'redux';
import RootReducer from "./reducers/root.reducer";
import logger from "./middleware/logger";
import test from "./middleware/test";
// 注册中间件 applyMiddleware(logger); 中间件的执行程序取决去注册的程序
export default createStore(RootReducer, applyMiddleware(logger, test));-
中间件通用性革新
/** * src/react-redux-guide/src/store/middleware/thunk.js */ import actionTypes from "../actionTypes"; export default store => next => action => { // if(action.type === actionTypes.countIncrementType || action.type === actionTypes.countDecrementType) { // // 开启提早操作 // setTimeout(() => { // next(action); // },2000) // } // 1.当这个中间件函数不关怀你想执行什么异步操作，只关怀你执行的是不是异步操作 // 2.如果你执行的是异步操作，再你触发action的时候，给中间件传递一个函数，如果执行的是同步操作就传递一个失常action对象 // 3.异步操作代码要写在传递进来的函数中 // 4.以后这个中间件的函数在点用你传递进来的函数时，要将dispatch办法传递进去 if(typeof action === 'function') { return action(store.dispatch); } next(action); }
/**
* src/react-redux-guide/src/store/middleware/thunk.js
*/
import actionTypes from './actionTypes';
const actions = {
// Counter
countIncrementAction: () => ({type: actionTypes.countIncrementType}),
countDecrementAction: () => ({type: actionTypes.countDecrementType}),
// 异步的action
countIncrementActionAsync: () => dispatch => {
setTimeout(() => {
dispatch(actions.countIncrementAction());
}, 2000);
},
// Modal
boxShowAction: () => ({type: actionTypes.boxShowType}),
boxHiddenAction: () => ({type: actionTypes.boxHiddenType}),
boxShowActionAsync: () => dispatch => {
setTimeout(() => {
dispatch(actions.boxShowAction());
}, 2000)
}
}
export default actions;3.Redux 罕用中间件
1.redux-thunk
redux-thunk 容许咱们在redux的工作流程中应用异步操作，与自定义thunk中间件用法雷同(src/react-redux-guide/src/store/middleware/thunk.js)
装置：npm install redux-thunk
容许action返回一个函数，这个函数承受一个dispatch参数，在这个函数当中做异步操作。
2.redux-thunk
redux-sage 能够将异步操作从ActionCreator文件中抽离进去，放在一个独自的文件中
1.创立 redux-sage 中间件
import createSagaMiddleware from 'redux-saga';
const sagaMiddleware = createSagaMiddleware();2.注册sagaMiddleware
createStore(reducer, appleMiddleware(sagaMiddleware));3.应用 saga 接管 action 执行一步操作
/**
* src/react-redux-guide/src/store/sagas/counter.saga.js
*/
import { takeEvery, put, delay} from 'redux-saga/effects';
import actionTypes from "../actionTypes";
import actions from "../actionCreators";
/**
* takeEvery: 接管 action
* put: 触发 action
* delay: 提早(这里不能够用setTimeout)
*/
function* countIncrement() {
yield delay(2000);
yield put(actions.countIncrementAction());
}
export default function* counterSaga () {
yield takeEvery(actionTypes.COUNTINCREMENTSAGATYPE, countIncrement)
}4.启用saga
/**
* src/react-redux-guide/src/store/index.js
*/
import { createStore, applyMiddleware } from 'redux';
import thunk from 'redux-thunk'; // 官网中间件
import createSagaMiddleware from 'redux-saga';
import counterSaga from './sagas/counter.saga'
import RootReducer from "./reducers/root.reducer";
// 自定义中间件
// import logger from "./middleware/logger";
// import test from "./middleware/test";
// import thunk from "./middleware/thunk";
// 注册中间件 applyMiddleware(logger); 中间件的执行程序取决去注册的程序
// 创立 saga
const sagaMiddleware = createSagaMiddleware();
// export default createStore(RootReducer, applyMiddleware(thunk));
export default createStore(RootReducer, applyMiddleware(sagaMiddleware));
// 启动 saga
sagaMiddleware.run(counterSaga)5.saga 中 action 传值
// 能够接管到 action 返回的对象
function* countIncrement(action) {
yield delay(2000);
// 获取 action 中的值并传递给下一个action
yield put(actions.countIncrementAction(action.value));
}
export default function* counterSaga () {
yield takeEvery(actionTypes.COUNTINCREMENTSAGATYPE, countIncrement)
}6.saga拆分合并
/**
* src/react-redux-guide/src/store/sagas/root.saga.js
*/
import { all } from 'redux-saga/effects';
import counterSaga from "./counter.saga";
import modalSaga from "./modal.saga";
// 合并Saga
export default function* rootSaga() {
yield all([
counterSaga(),
modalSaga()
])
}/**
* src/react-redux-guide/src/store/index.js
*/
// 批改启动 saga
sagaMiddleware.run(rootSaga);4.redux-actions
redux流程中大量的样板代码编写是十分苦楚的，应用 redux-actions能够简化action和reducer的解决
- 下载
npm install redux-actions -
创立 Action
/** * src/react-redux-guide/src/store/actions/counter.actions.js */ import { createAction } from 'redux-actions'; // 接管和触发action只须要应用 createAction() 的返回值就能够 export const incrementAction = createAction('increment'); export const decrementAction = createAction('decrement'); -
创立Reducer
/** * src/react-redux-guide/src/store/reducers/counter.reducer.js */ import { handleActions as createReducer } from 'redux-actions'; import * as counterActions from '../actions/counter.actions'; /** * handleActions 返回值就是reducer函数 */ const initialState = { count: 0, } const handleIncrement = (state, action) => ({count: state.count + 1}) const handleDecrement = (state, action) => ({count: state.count - 1}) export default createReducer({ [counterActions.incrementAction]: handleIncrement, [counterActions.decrementAction]: handleDecrement, }, initialState);3.redux-actions传值
redux-action 传值并不需要再actions中去接管，默认会挂载到 action.payload 的属性中
/**
* src/react-redux-guide/src/components/Counter.js
*/
import React from 'react';
import { connect } from 'react-redux';
import * as counterActions from '../store/actions/counter.actions';
const Counter = (props) => {
const {count, handleCountPlus, handleCountMinus} = props;
return (
<section>
<button onClick={() => handleCountPlus(10)}>Plus</button>
<span>{count}</span>
<button onClick={() => handleCountMinus(10)}>Minus</button>
</section>
)
}
const mapStateToProps = state => ({
count: state.counter.count
})
const mapDispatchToProps = dispatch => ({
handleCountPlus(value) {
dispatch(counterActions.incrementAction(value)) // redux-actions
},
handleCountMinus (value){
dispatch(counterActions.decrementAction(value)) // redux-actions
}
})
export default connect(mapStateToProps, mapDispatchToProps)(Counter);/**
* src/react-redux-guide/src/store/actions/counter.actions.js
*/
import { createAction } from 'redux-actions';
// 这里不须要去接管传递的值
// export const incrementAction = createAction('increment', value); 谬误
export const decrementAction = createAction('decrement');/**
* src/react-redux-guide/src/store/reducers/counter.reducer.js
*/
// 应用 redux-action 简化reducer
const handleIncrement = (state, action) => ({count: state.count + action.payload})
const handleDecrement = (state, action) => ({count: state.count - action.payload})
export default createReducer({
[counterActions.incrementAction]: handleIncrement,
[counterActions.decrementAction]: handleDecrement,
}, initialState);5. 实战案例
-
src/shopping-demo：前端文件- 启动
npm start - 端口
localhost:3000
- 启动
-
src/shoppingCartService： 服务端文件- 启动
npm start - 端口
localhost:3005
- 启动
四、 Redux 源码实现
五、Redux-toolkit
1.概述
redux toolkit 对 redux 进行的二次封装，用于高效的 Redux 开发，使 Redux 的应用变得简略。
2.疾速入门
- 创立状态切片
对于状态切片，咱们能够认为他就是本来的Redux中的那一个个小的reducer函数。
在Redux中，本来的 Reducer 函数和 Action 对象须要别离创立，当初通过状态切片来代替，它会返回 reducer 函数和 Action 对象。
import {createSlice} from "@reduxjs/toolkit";
const TODOS_FEATURE_KEY = 'todos';
const {reducer: todoReducer, actions } = createSlice({
name: TODOS_FEATURE_KEY, // 切片名称
initialState: [], // 切片状态
reducers: {
// 创立 actionCreator 和状态处理函数
// addTodo 是 action 的名称
addTodo: (state, action) => {
// 在 redux-toolkit 中应用createSlice 能够间接批改 state 的值，而并不需要返回一个新的状态
state.push(action.payload);
}
}
});
export const {addTodo} = actions;
export default todoReducer;2.创立 store
import {configureStore} from "@reduxjs/toolkit";
import TodosReducer, {TODOS_FEATURE_KEY} from "./todos.slice";
export default configureStore({
reducer: {
[TODOS_FEATURE_KEY]: TodosReducer
},
devTools: process.env.NODE_ENV !== 'production'
});3.配置Provider
import React from 'react';
import ReactDOM from 'react-dom/client';
import {Provider} from "react-redux";
import App from './App';
import store from "./Store";
const root = ReactDOM.createRoot(document.getElementById('root'));
root.render(
<React.StrictMode>
<Provider store={store}>
<App/>
</Provider>
</React.StrictMode>
);4.组件中触发Action
import {useDispatch, useSelector} from "react-redux";
import {TODOS_FEATURE_KEY, addTodo} from "../../Store/todos.slice";
const Todo = () => {
// 获取dispatch办法
const dispatch = useDispatch();
// 获取最新的状态
const todos = useSelector(state => state[TODOS_FEATURE_KEY]);
return (
<div>
<button onClick={() => dispatch(addTodo({title: '测试工作'}))}>增加工作</button>
<ul>
{
todos && todos.map(todo => (
<li key={todo.title}>{todo.title}</li>
))
}
</ul>
</div>
)
}
export default Todo;- action 预处理
当 Action 被触发后，能够通过prepare办法进行预处理，解决实现后交给Reduce.prepare办法必须返回对象
import {createSlice} from "@reduxjs/toolkit";
export const TODOS_FEATURE_KEY = 'todos';
// 应用 reducer.prepare 进行 action 预处理
const {reducer: TodosReducer, actions } = createSlice({
name: TODOS_FEATURE_KEY, // 切片名称
initialState: [], // 切片状态
reducers: {
// 创立 actionCreator
addTodo: {
// 状态处理函数
reducer: (state, action) => {
console.log('reducer', action);
state.push(action.payload)
},
// action预处理，必须返回一个对象 {payload: {...todo, title: 'haha'}}， 笼罩原有的payload
prepare: todo => {
console.log('prepare', todo)
// 批改 action 传过来的数据
return {
payload: {id: Math.random(), ...todo}
}
}
}
}
});
export const {addTodo} = actions;
export default TodosReducer;- 执行异步的操作形式
第一种形式
import {createSlice, createAsyncThunk} from "@reduxjs/toolkit";
import axios from 'axios';
export const TODOS_FEATURE_KEY = 'todos';
/**
* 异步操作：第一种
* createAsyncThunk('action-type', (payload, thunkAPI) => {异步操作})
*/
// 定义申请办法
const loadTodos = createAsyncThunk('async-load-todos', (payload, thunkAPI) => {
axios.get(payload)
.then(res => {
// 触发保留数据action setTodos
thunkAPI.dispatch(setTodos(res.data));
})
.catch(err => new Error(err))
});
// 应用 reducer.prepare 进行 action 预处理
const {reducer: TodosReducer, actions } = createSlice({
name: TODOS_FEATURE_KEY, // 切片名称
initialState: [], // 切片状态
reducers: {
// 创立 actionCreator
addTodo: {
// 状态处理函数
reducer: (state, action) => {
console.log('reducer', action);
state.push(action.payload)
},
// action预处理，必须返回一个对象 {payload: {...todo, title: 'haha'}}， 笼罩原有的payload
prepare: todo => {
console.log('prepare', todo)
// 批改 action 传过来的数据
return {
payload: {id: Math.random(), ...todo}
}
}
},
setTodos: (state, action) => action.payload
}
});
// jsx
export const {addTodo, setTodos} = actions;
export {loadTodos};
export default TodosReducer;
import {TODOS_FEATURE_KEY, addTodo, loadTodos} from "../../Store/todos.slice";
import {useDispatch, useSelector} from "react-redux";
import {useEffect} from "react";
const Todo = () => {
// // 获取dispatch办法
const dispatch = useDispatch();
// // 获取最新的状态
const todos = useSelector(state => state[TODOS_FEATURE_KEY]);
// // 组件挂载实现之后申请
useEffect(() => {
dispatch(loadTodos('http://localhost:3001/todos'));
}, [])
return (
<div>
<button onClick={() => dispatch(addTodo({title: '测试工作'}))}>增加工作</button>
<ul>
{
todos && todos.map(todo => (
<li key={todo.title}>{todo.title}</li>
))
}
</ul>
</div>
)
}
export default Todo;第二种形式
import {createSlice, createAsyncThunk} from "@reduxjs/toolkit";
import axios from 'axios';
export const TODOS_FEATURE_KEY = 'todos';
/**
* 异步操作：第二种
* createAsyncThunk('action-type', payload => {异步操作})
* 不须要再去编写保留数据的action, 能够间接在extraReducers中解决异步的action
*/
const loadTodos = createAsyncThunk('async-load-todos', payload => {
return axios.get(payload)
.then(res => res.data)
.catch(err => new Error(err));
})
// 应用 reducer.prepare 进行 action 预处理
const {reducer: TodosReducer, actions } = createSlice({
name: TODOS_FEATURE_KEY, // 切片名称
initialState: [], // 切片状态
reducers: {
// 创立 actionCreator
addTodo: {
// 状态处理函数
reducer: (state, action) => {
console.log('reducer', action);
state.push(action.payload)
},
// action预处理，必须返回一个对象 {payload: {...todo, title: 'haha'}}， 笼罩原有的payload
prepare: todo => {
console.log('prepare', todo)
// 批改 action 传过来的数据
return {
payload: {id: Math.random(), ...todo}
}
}
},
setTodos: (state, action) => action.payload
},
// 第二种异步申请编写形式：extraReducers 解决异步申请
extraReducers: {
// 解决 loadTodos 返回的 Promise 对象的胜利状态
[loadTodos.fulfilled]: (state, action) => {
console.log('fulfilled');
return action.payload;
},
[loadTodos.pending]: (state, action) => {
console.log('pending');
return state;
},
}
});
export const {addTodo, setTodos} = actions;
export {loadTodos};
export default TodosReducer;
// jsx
import {TODOS_FEATURE_KEY, addTodo, loadTodos} from "../../Store/todos.slice";
import {useDispatch, useSelector} from "react-redux";
import {useEffect} from "react";
const Todo = () => {
return (
<div>
<button onClick={() => dispatch(addTodo({title: '测试工作'}))}>增加工作</button>
<ul>
{
todos && todos.map(todo => (
<li key={todo.title}>{todo.title}</li>
))
}
</ul>
</div>
)
}
export default Todo;-
配置中间件
import {configureStore, getDefaultMiddleware} from "@reduxjs/toolkit"; import TodosReducer, {TODOS_FEATURE_KEY} from "./todos.slice"; import logger from 'redux-logger'; export default configureStore({ reducer: { [TODOS_FEATURE_KEY]: TodosReducer }, /** * middleware: [] 默认隐式的会挂载 @reduxjs/toolkit 内置的中间件 * 如果显示编写进去并增加自定义或者其余中间件时，须要通过getDefaultMiddleware()办法获取内置的中间件并挂载下来，不然内置的中间件就会被笼罩 */ middleware: [...getDefaultMiddleware(), logger], devTools: process.env.NODE_ENV !== 'production' }); -
实体适配器
将状态放入实体适配器，实体适配器提供操作状态的各种办法，简化操作。- 创立实体适配器
import {createEntityAdapter} from "@reduxjs/toolkit"; import axios from 'axios'; export const TODOS_FEATURE_KEY = 'todos'; const loadTodos = createAsyncThunk('async-load-todos', (payload, thunkAPI) => { axios.get(payload) .then(res => { // 触发保留数据action setTodos thunkAPI.dispatch(setTodos(res.data)); }) .catch(err => new Error(err)) }); /** * 创立实体适配器 * todosAdapter.getInitialState(); // entities: {} 存储状态 ids: [] 存储每一条状态的 id */ const todosAdapter = createEntityAdapter(); const {reducer: TodosReducer, actions } = createSlice({ name: TODOS_FEATURE_KEY, // 切片名称 // 将状态放入适配器当中 initialState: todosAdapter.getInitialState(), reducers: { // 创立 actionCreator addTodo: { // 状态处理函数 reducer: (state, action) => { // 应用状态适配器向状态中增加数据 todosAdapter.setOne(state, action.payload); // 增加一条 }, // action预处理，必须返回一个对象 {payload: {...todo, title: 'haha'}}， 笼罩原有的payload prepare: todo => ({payload: {id: Math.random(), ...todo}}) }, setTodos: (state, action) => todosAdapter.setMany(state, action.payload), }, }); export const {addTodo, setTodos} = actions; export {loadTodos}; export default TodosReducer;
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简化实体适配器
const {reducer: TodosReducer, actions } = createSlice({ name: TODOS_FEATURE_KEY, // 切片名称 // 将状态放入适配器当中 initialState: todosAdapter.getInitialState(), reducers: { // 创立 actionCreator addTodo: { /** * 简化实体适配器函数，自动检测第二个是否是action参数，如果是action的话就会去找action.payload并将其放到state中 */ reducer: todosAdapter.setOne, // action预处理，必须返回一个对象 {payload: {...todo, title: 'haha'}}， 笼罩原有的payload prepare: todo => { console.log('prepare', todo) // 批改 action 传过来的数据 return { payload: {id: Math.random(), ...todo} } } }, setTodos: todosAdapter.setMany } }); - 更改实体适配器的惟一示意
实体适配器要求每一个实体必须领有 id 属性作为惟一标识，如果实体中的惟一标识字段不叫作 id, 须要应用 selectId 进行申明。
const todosAdapter = createEntityAdapter({ selectId: todo => todo.cid})-
状态选择器
提供了从实体状态器中获取状态的快捷路径。import {createSelector} from '@reduxjs/toolkit'; /** * 创立状态选择器 * createSelector(相应的state, 具体的状态选择器(由实体适配器返回) */ const {selectAll} = todosAdapter.getSelectors(); export const selectorTodos = createSelector(state => state[TODOS_FEATURE_KEY], selectAll); // jsx const dispatch = useDispatch(); // 应用状态选择器获取状态 const todos = useSelector(selectorTodos); useEffect(() => { dispatch(loadTodos('http://localhost:3001/todos')); }, [])
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