React - 在React中简单应用Redux

我就是我 2022-04-15 06:57 179阅读 0赞

[Redux][]

引入Redux就是为了方便管理状态，那么在React代码中如何使用了。

换句话说就是如何使用storea里面维护的state，然后在react中如何产生action,用于更新state。

我们需要用的一个connect函数。

具体看代码

import React from "react";
    import ReactDOM from "react-dom";
    import { createStore, combineReducers, bindActionCreators } from "redux";
    import { Provider, connect } from "react-redux";
    
    import "./styles.css";
    
    const initState = { count: 0 }; //默认初始状态
    const counter = (state = initState, action) => {
      switch (action.type) {
        case "add": // + 1
          return { count: state.count + 1 };
        case "sub": // - 1
          return { count: state.count - 1 };
        case "addAny": // + action.num
          return { count: state.count + action.num };
        default:
          break;
      }
      return state;
    };
    
    const store = createStore(counter); //生成store
    
    function addOne() {
      //action产生函数   返回一个add  action
      return {
        type: "add"
      };
    }
    
    function subOne() {
      // 返回一个sub  action
      return {
        type: "sub"
      };
    }
    
    function subAnyCount(cnt) {
      // 返回一个add cnt  action
      return {
        type: "addAny",
        num: cnt
      };
    }
    
    
    class Counter extends React.Component {
      constructor(props) {
        super(props);
      }
      render() {
        const { count, addOne, subOne } = this.props;
        //接受到的三个参数，
        return (
          <div>
            <button onClick={subOne}>-</button>
            <span> {count}</span>
            <button onClick={addOne}>+</button>
          </div>
        );
      }
    }
    //定义了一个函数，用于返回我需要的state.count
    function mapStatesToProps(state) {
      return {
        count: state.count
      };
    }
    //因为action都需要dispatch,
    function mapdispatchToProps(dispatch) {
      return bindActionCreators({ addOne, subOne }, dispatch);
    }
    //这是关键，Counter就会接受到三个参数
    const ConnectCounter = connect(
      mapStatesToProps,
      mapdispatchToProps
    )(Counter);
    const html = (
      <Provider store={store}>
        <ConnectCounter />
      </Provider>
    );
    ReactDOM.render(html, document.getElementById("root"));

![20181122211550657.png][]

效果如图，点击+，则+1，点击-，则-1

[Redux]: https://blog.csdn.net/wust_cyl/article/details/84337752
[20181122211550657.png]: /images/20220415/ccb6fc9926784c57917cebe4c9831ce9.png