react父组件更改props子组件无法刷新原因及解决方法

export default class Parent2 extends Component {
    constructor(props){
        super(props)
//初始化state
        this.state={
            parentVal: 10,
        }
    }

    count=1
    handleClick=()=>{
        this.setState({
            parentVal:this.state.parentVal+1
        })
    }

    changeCount=()=>{
        this.count=this.count+1
        console.log(this.count)
    }

    componentDidMount() {
        console.log("父组件生命周期======：Mount")
    }

    //挂载完成后更新状态值，render()结束后会执行componentDidUpdate()钩子函数
    componentDidUpdate(prevProps, prevState, snapshot) {
        console.log("父组件生命周期======：Update")
    }

    componentWillUnmount() {
        console.log("父组件生命周期======：Unmount")
    }
    render() {
        console.log("父组件生命周期======：render")
        return (
            <div>
                父组件
                <p>{this.state.parentVal}</p>
                <Divider>分割线</Divider>

                <Button   color='primary' size='small' onClick={this.handleClick}>更改state的值</Button>
                <p>父组件调用setState()时，子组件也会执行render()方法，</p>
                <Button   color='primary' size='small' onClick={this.changeCount}>更改count的值</Button>



                <Child2 number={this.state.parentVal} count={this.count}/>
            </div>

        )
    }
}

export default class Child2 extends Component {

    constructor(props){
        super(props)
    }
    componentDidMount() {
        console.log("子组件生命周期======：Mount")
    }
    //挂载完成后更新状态值，render()结束后会执行componentDidUpdate()钩子函数
    componentDidUpdate(prevProps, prevState, snapshot) {
        console.log("子组件生命周期======：Update")
    }

    componentWillUnmount() {
        console.log("子组件生命周期======：Unmount")
    }
    render() {
        console.log("子组件生命周期======：render")
        return (
            <div style={{background:'yellow',padding:20}}>
               <p>父组件state中传值：{this.props.number}</p>
                <p>父组件非state中传值：{this.props.count}</p>
            </div>

        )
    }
}