react学习——21react中消息的订阅与发布

1、安装 pubsub-js

npm install pubsub-js

2、消息发布

PubSub.publish('update-list',{isLoding:false,users:res.data.items});

3、消息订阅

```javascript
componentDidMount() {
        //订阅消息
        PubSub.subscribe('update-list',(msg,keyword)=>{
            this.setState(keyword)
    })

4、完整代码
App.js

```javascript
//创建“外壳”组件APP
import React, {Component} from "react";
//引入Search组件
import Search from "./components/Search";
//引入List组件
import List from "./components/List";
//创建并暴露App组件
export default class App extends Component {


    render() {
        return (
            <div className="container">
                <Search ></Search>
                <List></List>
            </div>
        )
    }
}

List组件

import React, {Component} from "react";
import PubSub from 'pubsub-js'
//引入样式
import "./index.css";
export default class List extends Component {
    state={
        users:[],
        isFirst:true,//是否第一次加载数据
        isLoding:false,//是否正在加载数据
        err:''//是否加载失败
    }
    componentDidMount() {
        //订阅消息
        PubSub.subscribe('update-list',(msg,keyword)=>{
            this.setState(keyword)
    })

    }
    render() {
        const {users,isFirst,isLoding,err}=this.state
        return(
            <div className="row">
                {
                    isFirst?<h2>欢迎使用，输入关键字，随后点击搜素</h2>:
                        isLoding?<h2>正在加载中...</h2>:
                            err?<h2 style={{color:'red'}}>{err}</h2>:
                    users.map((userObj)=>{
                        return(
                            <div key={userObj.id}  className="card">
                                <a href={userObj.html_url} target="_blank" rel="noreferrer">
                                    <img alt={"reactjs"} src={userObj.avatar_url} style={{width: '100px'}}/>
                                </a>
                                <p className="card-text">{userObj.login}</p>
                            </div>
                        )
                    })
                }
            </div>
        );
    }
}

样式

.album {
    min-height: 50rem; /* Can be removed; just added for demo purposes */
    padding-top: 3rem;
    padding-bottom: 3rem;
    background-color: #f7f7f7;
}

.card {
    float: left;
    width: 33.333%;
    padding: .75rem;
    margin-bottom: 2rem;
    border: 1px solid #efefef;
    text-align: center;
}

.card > img {
    margin-bottom: .75rem;
    border-radius: 100px;
}

.card-text {
    font-size: 85%;
}

search组件

import React, {Component} from "react";
import PubSub from 'pubsub-js'
//引入axios
import axios from 'axios';
export default class Search extends Component {
    search = () =>{
        //获取用户的输入(连续解构赋值+重命名)
        const {keyword:{value:keyword}} = this;
        //发送请求前通知List组件更新状态
        /*this.props.updateAppState({isFirst:false,isLoding: true});*/
        PubSub.publish('update-list',{isFirst:false,isLoding: true});
        //发送网络请求   https://api.github.com/search/users?q=xxxxxx
        axios.get(`https://api.github.com/search/users?q=${keyword}`).then(
            res=>{
                //请求成功后通知List组件更新状态
                // const {items} = res.data;
                // this.props.updateAppState({isLoding:false,users:items});
                // console.log(items)
                PubSub.publish('update-list',{isLoding:false,users:res.data.items});
            },
            err=>{
                //请求失败通知App组件更新状态
                // this.props.updateAppState({isLoding:false,err:err.message});
                PubSub.publish('update-list',{isLoding:false,err:err.message});
            }
        )
    }
    render()
    {
        return(
            <section className="jumbotron">
                <h3 className="jumbotron-heading">Search Github Users</h3>
                <div>
                    <input ref={c=>this.keyword=c} type="text" placeholder="enter the name you search"/>&nbsp;
                    <button onClick={this.search}>Search</button>
                </div>
            </section>
        );
    }
}