redux的使用

react-native,react,react-redux,react-navigaition,redux-thunk,redux-persist

用户发出action,reducer函数算出新的state,view重新渲染

三大原则

1. 单一数据源，利用props的形式向下传播（react数据流决定）

2. state只读，通过action修改

3. 通过纯函数reducer来修改组件状态，reducer是描述action动作的纯函数

react-redux 连接react和redux

import { connect,Provider } from 'react-redux'

connet([mapStateToProps],[mapDispatchToProps],[mergeProps])(App)

• mapStateToProps: 基于全局的state，选择我们要注入的props

• 不同的组件分开connec

function select(state){
    return{
        // 把state.todos注入，读取方法： this.props.visibleTodo
        visibleTodo: state.todos
    }
}

const todoApp connect(select)(App)
// export default todoApp

// store = "balabala"
<Provider store={store}>
    <todoApp />
</Provider>

redux三剑客

// 先确定一下初始状态（状态表示的格式）
export default {
    money: 0,lastJob:'no job'
}

ACTION

• 定义动作，比如抢劫银行、搬砖，但是怎么抢怎么搬还是reducer来定

/**
 * Created by liuyiman on 2017/7/3.
 */

// 定义一个menoy+的action
function addmoney(money){
    return {
        // 可以用一个文件管理type，之所以是type是因为我的reducer要根据这个来判断
        type: 'ADD_MONEY',money
    }
}
function setLastJob(job){
    return {
        type: 'SET_JOB',job
    }
}
// 定义一个赚钱的方式1 ，抢劫银行
export function robBank(){
    return (dispatch,getState) => {
        // 赚一百万
        let { earn } = getState()
        dispatch(addmoney(earn.money + 1000000))
        return dispatch(setLastJob('robber'))
    }
}
// 定义一个赚钱的方式2，建材转移者
export function moveBrick(){
    return (dispatch,getState) => {
        console.log('s',getState())
        let { earn } = getState()
        // 赚一块钱
        dispatch(addmoney( earn.money + 1 ))
        dispatch(setLastJob('brick mover'))
    }
}
// 破产,数据清零
export function goBroke() {
    return {
        type: 'BROKE',money: 0,job:'broke'
    }
}

reducers

• 描述action如何改变store(in fact state)

import { combineReducers } from 'redux'
import initializeState from './initializeState'
// 定义一个reducer
function earn( state = initializeState,action ) {
    switch (action.type) {
        case 'ADD_MONEY':
            return{
                ...state,money:action.money
            }
        case 'SET_JOB':
            return{
                ...state,lastJob:action.job
            }
        case 'BROKE':
            return{
                ...state,money:action.money,lastJob:action.job
            }
        default:
            return state
    }
}

export default earn

store

• 不同的组件可以 connet 到不同的 store

import { createStore,applyMiddleware,compose,combineReducers } from 'redux'
import thunkMidlleware from 'redux-thunk'
import earn from './reducers'
import { persistStore,autoRehydrate} from 'redux-persist'
import { AsyncStorage } from 'react-native'

// base reducer
let baseReducers = {
    earn: earn
}
/*
* 考虑到后面要将react-navigation的reducer加进来，使用redux-persist,所以写了这个helper
* const store = configStore(reducers)()
* */
const configStore = function (reducers = {}) {
    const rootReducer = combineReducers({
        ...baseReducers,...reducers
    })
    return function (_options = {}) {
        const store = createStore(
            rootReducer,_options.initialState,compose(
                applyMiddleware(thunkMidlleware),autoRehydrate()
            )
        )
        const options = {
            storage: AsyncStorage,blacklist: _options.blacklist
        }
        persistStore(store,options)
        return store
    }
    
}

export default configStore

more

中间件 middleware

• 对store.dispatch的重新定义

• 在发出action和执行reducer之间，添加了其他功能

redux-thunk

使dispatch可以接受函数说作为参数，使异步的action可以被触发

// 无论killSomeOne是Action create还是普通的返回{}的action
this.props.dispath(killSomeOne('vincent'))

redux-persist

本地保存store状态（react-native 本地缓存），可以设置白名单黑名单自动保存等等，特别好用

/*
* 考虑到后面要将react-navigation的reducer加进来，使用redux-persist,options)
        return store
    }
    
}

export default configStore

react-navigation + redux

import React,{ Component } from 'react';
import {
  AppRegistry,StyleSheet,Text,View,Button
} from 'react-native';
// navigation
import { TabNavigator,addNavigationHelpers,StackNavigator } from 'react-navigation'
// for connect redux and react
import { Provider,connect } from 'react-redux'
import configStore from './redux/store'
// import actions
import {moveBrick,robBank,goBroke} from './redux/actions'
// initialState
import initialState from './redux/store'

// 赚钱页面
class Earn extends Component {
  constructor(props) {
    super(props)
  }
  render(){
    const { earn,dispatch } = this.props
    console.log( 'saa',initialState,earn )
    return(
        <View style={styles.container}>
          <Text>先赚一个亿！</Text>
          <Text>my money$:{earn.money}</Text>
          <Text>my last job:{earn.lastJob}</Text>
          <Button title="rob a bank" onPress={() => dispatch(robBank())}/>
          <Button title="move some Brick" onPress={() => dispatch(moveBrick())}/>
          <Text>价格指导：搬砖 -> $1; 打劫 -> $1000000</Text>
            <Button title="broke" onPress={() => dispatch(goBroke())}/>
        </View>
        )
  }
}

// 传入 earn页面的redux
const earnSelect = function (state) {
    return{
        earn: state.earn
    }
}
// 连接，吧earn上面的select传入earn的props里面
const ConnnetedEarn = connect(earnSelect)(Earn)

// tab navigation的另一个页面
class Screen extends Component{
    constructor(props){
        super(props)
    }
    render() {
        const { navigate } = this.props.navigation
        return(
            <View style={styles.container}>
                <Text>SCREEN!</Text>
                <Button title="to stack2" onPress={() => {navigate('Stack2')}}/>
            </View>
        )
    }
}

// 注册一个tag navigator
const AppNav = TabNavigator({
    'earn':{
        screen: ConnnetedEarn
    },'screen': {
        screen: Screen
    }
})

// stack navigation 的页面
class Stack2 extends Component {
    constructor(props){
        super(props)
    }
    render(){
        const {navigate} = this.props.navigation
        return (
            <View style={styles.container}>
                <Text>Stack2</Text>
                <Button title="TO APP NAV" onPress={() => navigate('screen')}/>
            </View>
        )
    }
}

/*
* 注册stack
* 一个是 上面的 tag navigation的页面
* 另一个是 上面的 stack2
* */
const StackNav = StackNavigator({
    App:{
        screen: AppNav,title: 'app'
    },Stack2: {
        screen: Stack2,title: 'stack2'
    }
})

const navInitialState = StackNav.router.getStateForAction(AppNav.router.getActionForPathAndParams('screen'))
const navReducer = (state = navInitialState,action) => {
    console.log('state:',state)
    let nextState = StackNav.router.getStateForAction(action,state);
    console.log('action',action)
    return nextState || state
}

/*
* 加入navReducer,生成store
* */
const store = configStore({
    nav: navReducer
})({
    blacklist:['nav']
})

/*
* stack app
* 利用addNavigationHelper吧navigation传进去
* */
class App extends Component{
    render(){
        return(
            <StackNav navigation={addNavigationHelpers({
                dispatch: this.props.dispatch,state: this.props.nav
            })} />
        )
    }
}

/*
* 把nav传进去
* */
function select(state) {
    console.log('state',state)
    return {
        nav: state.nav
    }
}
/*
* connect connect!
* */
const ConnectedApp = connect(select)(App)


// 加上 provider和store
class reduxLearn extends Component {
  render() {
    return (
        <Provider store={store}>
          <ConnectedApp/>
        </Provider>
    );
  }
}

const styles = StyleSheet.create({
  container: {
    flex: 1,justifyContent: 'center',alignItems: 'center',backgroundColor: '#F5FCFF',},welcome: {
    fontSize: 20,textAlign: 'center',margin: 10,instructions: {
    textAlign: 'center',color: '#333333',marginBottom: 5,});

// 注册
AppRegistry.registerComponent('reduxLearn',() => reduxLearn);