• Provider

       //最后导出的是createProvider()。所以一开始storeKey应该是以默认值‘store’传进去的
       function createProvider(storeKey = 'store', subKey) {
       const subscriptionKey = subKey || `${storeKey}Subscription`
    
       class Provider extends Component {
           //设置context,能让子组件拿到store
           //相当于返回 {store: this.store}
           getChildContext() {
             return { [storeKey]: this[storeKey], [subscriptionKey]: null }
           }
    
           constructor(props, context) {
             super(props, context)
             //this.store = props.store
             this[storeKey] = props.store;
           }
    
           render() {
             //只能有一个子组件
             return Children.only(this.props.children)
           }
       }
       
       //props和context类型验证
       Provider.propTypes = {
           store: storeShape.isRequired,
           children: PropTypes.element.isRequired,
       }
       Provider.childContextTypes = {
             [storeKey]: storeShape.isRequired,
            [subscriptionKey]: subscriptionShape,
        }
    
            return Provider
    }

通常的做法是我们先通过redux创建好store,然后赋给Provider组件的store属性。在Provider组件内部,拿到这个store,设置为context属性,这样就能让它的所有组件都能通过context拿到store。

   <Provider store={store}>
       <App />
   </Provider>

本文固定链接: http://www.js-code.com/react/react_42890.html