[英]Calling a method on a particular instance of a React component from another component
我正在尝试制作一个简单的番茄钟计时器。 我需要使暂停和停止按钮工作。 我定义了一个名为“Timer”的单独组件并添加了两个按钮:“Pause”和“Stop”,这显然必须影响 Timer 的状态。
按下相应按钮时如何调用 Timer 的停止和暂停方法?
我知道我可以通过简单地在 Timer 类中包含按钮来做到这一点,但我想学习如何在未来实现类似的东西,我想保持 Timer 的计数器部分独立。
这是代码:
import React from 'react'
import { Text, View, Button, StyleSheet } from 'react-native';
import { Constants } from 'expo';
class Timer extends React.Component{
constructor (props){
super(props)
this.state = {
minutes: props.minutes,
seconds: props.seconds,
count: 0,
}
}
dec = () => {
this.setState(previousState => {
if (previousState.seconds==0){
return {
minutes: previousState.minutes-1,
seconds: 59,
count: previousState.count+1,
}
}
else{
return{
minutes: previousState.minutes,
seconds: previousState.seconds-1,
count: previousState.count+1,
}
}
});
}
componentDidMount (){
setInterval(this.dec,1000);
}
render (){
return(
<View style = {{flexDirection: 'row'}}>
<Text style = {styles.timerCount}> {this.state.minutes}</Text>
<Text style = {styles.timerCount}>:</Text>
<Text style = {styles.timerCount}> {this.state.seconds} </Text>
</View>
)
}
stop (){
console.log('stop')
}
pause (){
console.log('pause')
}
}
export default class App extends React.Component {
stop (){
console.log('stop')
}
render() {
return(
<View style={styles.container}>
<Timer style = {styles.timer} minutes={25} seconds = {0}/>
<View style = {styles.buttonContainer}>
<Button title = 'Pause' style = {styles.timerButton} color = 'white' onPress = {()=>{console.log("call the timer's pause method here")}}/>
<Button title = 'Stop' style = {styles.timerButton} color = 'white' onPress = {()=>{console.log("call the timer's stop method here")}}/>
</View>
</View>
);
}
}
const styles = StyleSheet.create({
buttonContainer: {
flexDirection: 'row',
},
container: {
flex: 1,
alignItems: 'center',
justifyContent: 'center',
paddingTop: 50,
backgroundColor: '#EC3D40',
},
timer: {
backgroundColor: '#EC3D40',
paddingTop: 50,
},
timerCount: {
fontSize: 48,
color: 'white',
backgroundColor: '#EC3D40',
paddingTop: 10,
paddingBottom: 10,
},
timerButton:{
borderColor: 'white',
backgroundColor: 'transparent',
}
});
那么实际上你可以使用ref功能来做到这一点。
您可以创建一个ref
并将其分配给您的计时器组件。 然后你可以调用这个组件的方法。
export default class App extends React.Component {
timerRef = React.createRef();
render() {
return(
<View style={styles.container}>
<Timer style = {styles.timer} minutes={25} seconds = {0} ref={this.timerRef}/>
<View style = {styles.buttonContainer}>
<Button title = 'Pause' style = {styles.timerButton} color = 'white' onPress = {()=>{console.log("call the timer's pause method here"); this.timerRef.current.pause();}}/>
<Button title = 'Stop' style = {styles.timerButton} color = 'white' onPress = {()=>{console.log("call the timer's stop method here"); this.timerRef.current.stop();}}/>
</View>
</View>
);
}
}
但这似乎不是一种反应式的做事方式。
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.