需要组件之进行通信的几种情况
? 父组件向子组件通信?
? 子组件向父组件通信?
? 跨级组件通信?
? 没有嵌套关系组件之间的通信?
1. 父组件向子组件通信
React数据流动是单向的,父组件向子组件通信也是最常见的;父组件通过props向子组件传递需要的信息?Child.jsx
import?React?from?‘react‘;
import?PropTypes?from?‘prop-types‘;
export?default?function?Child({?name?})?{???
?return?
?<h1>Hello,?{name}</h1>;
}
Child.propTypes?=?{????
??name:?PropTypes.string.isRequired,
};
Parent.jsx
import?React,?{?Component?}?from?‘react‘;
import?Child?from?‘./Child‘;
class?Parent?extends?Component?{
????render()?{????????
????return?(????????????
????????????<div>
????????????????<Child?name="Sara"?/>
????????????</div>
????????);
????}
}
export?default?Parent;
2. 子组件向父组件通信
? 利用回调函数?
? 利用自定义事件机制?
回调函数
实现在子组件中点击隐藏组件按钮可以将自身隐藏的功能
List3.jsx
import?React,?{?Component?}?from?‘react‘;
import?PropTypes?from?‘prop-types‘;
class?List3?extends?Component?{????
static?propTypes?=?{????????
????????hideConponent:?PropTypes.func.isRequired,
????}
????render()?{??????
??????return?(????????????
??????????<div>
????????????????哈哈,我是List3???????????????
?????????????????<button?onClick={this.props.hideConponent}>隐藏List3组件</button>
????????????</div>
????????);
????}
}
export?default?List3;
App.jsx
import?React,?{?Component?}?from?‘react‘;
import?List3?from?‘./components/List3‘;
export?default?class?App?extends?Component?{???
?constructor(...args)?{????????
?super(...args);????????
?????this.state?=?{???????????
??????isShowList3:?false,
????????};
????}
????showConponent?=?()?=>?{???????
?????this.setState({????????????
?????isShowList3:?true,
????????});
????}
????
????hideConponent?=?()?=>?{??????
??????this.setState({?????????
?????????isShowList3:?false,
????????});
????}
????
????render()?{????????
?????????return?(???????????
?????????????<div>
????????????????<button?onClick={this.showConponent}>显示Lists组件</button>
????????????????{
????????????????????this.state.isShowList3??<List3?hideConponent={this.hideConponent}?/>:null
????????????????}????????????
?????????????</div>
????????);
????}
}
观察一下实现方法,可以发现它与传统回调函数的实现方法一样.而且setState一般与回调函数均会成对出现,因为回调函数即是转换内部状态是的函数传统;
3. 跨级组件通信
? 层层组件传递props?
例如A组件和B组件之间要进行通信,先找到A和B公共的父组件,A先向C组件通信,C组件通过props和B组件通信,此时C组件起的就是中间件的作用
? 使用context?
context是一个全局变量,像是一个大容器,在任何地方都可以访问到,我们可以把要通信的信息放在context上,然后在其他组件中可以随意取到;
但是React官方不建议使用大量context,尽管他可以减少逐层传递,但是当组件结构复杂的时候,我们并不知道context是从哪里传过来的;而且context是一个全局变量,全局变量正是导致应用走向混乱的罪魁祸首.
使用context
下面例子中的组件关系: ListItem是List的子组件,List是app的子组件
ListItem.jsx
import?React,?{?Component?}?from?‘react‘;import?PropTypes?from?‘prop-types‘;class?ListItem?extends?Component?{????//?子组件声明自己要使用context
????static?contextTypes?=?{????????color:?PropTypes.string,
????}????static?propTypes?=?{????????value:?PropTypes.string,
????}
????render()?{????????const?{?value?}?=?this.props;????????return?(????????????<li?style={{?background:?this.context.color?}}>
????????????????<span>{value}</span>
????????????</li>
????????);
????}
}export?default?ListItem;
List.jsx
import?ListItem?from?‘./ListItem‘;class?List?extends?Component?{????//?父组件声明自己支持context
????static?childContextTypes?=?{????????color:?PropTypes.string,
????}????static?propTypes?=?{????????list:?PropTypes.array,
????}????//?提供一个函数,用来返回相应的context对象
????getChildContext()?{????????return?{????????????color:?‘red‘,
????????};
????}
????render()?{????????const?{?list?}?=?this.props;????????return?(????????????<div>
????????????????<ul>
????????????????????{
????????????????????????list.map((entry,?index)?=>????????????????????????????<ListItem?key={list-${index}}?value={entry.text}?/>,
???????????????????????)
????????????????????}????????????????</ul>
????????????</div>
????????);
????}
}
export?default?List;
App.jsx
import?React,?{?Component?}?from?‘react‘;import?List?from?‘./components/List‘;const?list?=?[
????{????????text:?‘题目一‘,
????},
????{????????text:?‘题目二‘,
????},
];export?default?class?App?extends?Component?{
????render()?{????????return?(????????????<div>
????????????????<List
????????????????????list={list}
????????????????/>
????????????</div>
????????);
????}
}
4. 没有嵌套关系的组件通信
? 使用自定义事件机制?
在componentDidMount事件中,如果组件挂载完成,再订阅事件;在组件卸载的时候,在componentWillUnmount事件中取消事件的订阅;
以常用的发布/订阅模式举例,借用Node.js Events模块的浏览器版实现
使用自定义事件的方式
下面例子中的组件关系: List1和List2没有任何嵌套关系,App是他们的父组件;
实现这样一个功能: 点击List2中的一个按钮,改变List1中的信息显示?首先需要项目中安装events 包：
npm?install?events?--save
在src下新建一个util目录里面建一个events.js
import?{?EventEmitter?}?from?‘events‘;export?default?new?EventEmitter();
list1.jsx
import?React,?{?Component?}?from?‘react‘;import?emitter?from?‘../util/events‘;class?List?extends?Component?{????constructor(props)?{????????super(props);????????this.state?=?{????????????message:?‘List1‘,
????????};
????}
????componentDidMount()?{????????//?组件装载完成以后声明一个自定义事件
????????this.eventEmitter?=?emitter.addListener(‘changeMessage‘,?(message)?=>?{????????????this.setState({
????????????????message,
????????????});
????????});
????}
????componentWillUnmount()?{
????????emitter.removeListener(this.eventEmitter);
????}
????render()?{????????return?(????????????<div>
????????????????{this.state.message}????????????</div>
????????);
????}
}export?default?List;
List2.jsx
import?React,?{?Component?}?from?‘react‘;import?emitter?from?‘../util/events‘;class?List2?extends?Component?{
????handleClick?=?(message)?=>?{
????????emitter.emit(‘changeMessage‘,?message);
????};
????render()?{????????return?(????????????<div>
????????????????<button?onClick={this.handleClick.bind(this,?‘List2‘)}>点击我改变List1组件中显示信息</button>
????????????</div>
????????);
????}
}
APP.jsx
import?React,?{?Component?}?from?‘react‘;import?List1?from?‘./components/List1‘;import?List2?from?‘./components/List2‘;export?default?class?App?extends?Component?{
????render()?{????????return?(????????????<div>
????????????????<List1?/>
????????????????<List2?/>
????????????</div>
????????);
????}
}
自定义事件是典型的发布订阅模式,通过向事件对象上添加监听器和触发事件来实现组件之间的通信
总结
? 父组件向子组件通信: props?
? 子组件向父组件通信: 回调函数/自定义事件?
? 跨级组件通信: 层层组件传递props/context?
? 没有嵌套关系组件之间的通信: 自定义事件?
React组件通信的几种方式
原文地址：http://blog.51cto.com/13127751/2136751