React中使用Redux (一) - 在React中直接使用Redux

React中使用Redux

开始之前需要强调一下，redux和react没有直接的关系，你完全可以在React, Angular, Ember, jQuery, or vanilla JavaScript中使用Redux。

这里我创建了两个组件:

首先将结构搭建出来, 然后安装redux库: npm i redux

安装完成后, 安装我们上一篇文章讲解的目录结构, 创建Store文件夹

import { createStore } from "redux";
import reducer from "./reducer";

const store = createStore(reducer)

export default store

export const CHANGE_NUM  = "change_num"

import { CHANGE_NUM } from "./constants"

const initialState = {
  counter: 10
}

export default function reducer(state = initialState, action) {
  switch(action.type) {
    case CHANGE_NUM:
      return {...state, counter: state.counter + action.num}
    default: 
      return state
  }
}

import { CHANGE_NUM } from "./constants"

export const changeNumAction = (num) => ({
  type: CHANGE_NUM,
  num
})

store中编写完成后, 在Home和Profile页面中使用store中的state, 核心代码主要是两个:

• Home组件

import React, { PureComponent } from 'react'
import store from '../store'
import { changeNumAction } from '../store/actionCreators'

export class Home extends PureComponent {
  constructor() {
    super()

    this.state = {
      counter: store.getState().counter
    }
  }

  // 核心一: 在componentDidMount中监听store的变化，当数据发生变化时重新设置 counter;
  componentDidMount() {
    store.subscribe(() => {
      const state = store.getState()
      this.setState({ counter: state.counter })
    })
  }

  // 核心二: 在发生点击事件时，调用store的dispatch来派发对应的action;
  changeNum(num) {
    store.dispatch(changeNumAction(num))
  }

  render() {
    const { counter } = this.state

    return (
      <div>
        <h2>Home</h2>
        <h2>当前计数: {counter} </h2>
        <button onClick={() => this.changeNum(1)}>+1</button>
        <button onClick={() => this.changeNum(5)}>+5</button>
      </div>
    )
  }
}

export default Home

• Profile组件

import React, { PureComponent } from 'react'
import store from '../store'
import { changeNumAction } from '../store/actionCreators'

export class Profile extends PureComponent {
  constructor() {
    super()

    this.state = {
      counter: store.getState().counter
    }
  }

  componentDidMount() {
    store.subscribe(() => {
      const state = store.getState()
      this.setState({ counter: state.counter })
    })
  }

  changeNum(num) {
    store.dispatch(changeNumAction(num))
  }

  render() {
    const { counter } = this.state

    return (
      <div>
        <h2>Profile</h2>
        <h2>当前计数: {counter}</h2>
        <button onClick={() => this.changeNum(-1)}>-1</button>
        <button onClick={() => this.changeNum(-5)}>-5</button>
      </div>
    )
  }
}

export default Profile

我们发现Home组件和Profile组件中的代码是大同小异的, 所以这不是我们最终编写的代码, 后面还会对代码进行优化