[英]How can I create a progress bar for an API request in React Native?
当我的程序获取天气数据时,我正在尝试制作一个简单的进度计数器,从0%到100%。 API请求通过由getLocation()
的内部index.ios.js
它调用fetchWeather()
的内部weatherApi.js
。 有没有办法测量fetch函数对我的API请求的进度? 如果没有,实施加载栏的好方法是什么?
weatherAPI.js
const rootUrl ='http://api.openweathermap.org/data/2.5/weather?appid=fcea54d0ceade8f08ab838e55bc3f3c0'
export const fetchWeather = (lat,lon) => {
const url = rootUrl+'&lat='+lat+'&lon='+lon+"&units=metric"
console.log(url)
return fetch(url)
.then(res => res.json())
.then(json => ({
temp: json.main.temp,
weather: json.weather[0].main
}))
}
index.ios.js
import React, {Component} from 'react';
import {
AppRegistry,
StyleSheet,
Text,
View,
StatusBar
} from 'react-native'
import Icon from 'react-native-vector-icons/Ionicons'
import {fetchWeather} from './weatherAPI'
import Highlight from 'react-native-highlight-words'
const iconNames = {
Default: 'md-time',
Clear: 'md-sunny',
Rain: 'md-rainy',
Thunderstorm: 'md-thunderstorm',
Clouds: 'md-cloudy',
Snow: 'md-snow',
Drizzle: 'md-umbrella',
}
const phrases = {
Default:{
title: "Fetchin the Weather",
subtitle: "Be patient, you're witnessing a miracle",
highlight: ["Fetchin"],
color: "#636363",
background: "#9C9C9C"
},
Clear: {
title: "CLEAR.",
subtitle: "You Better Go Outside",
highlight: ["CLEAR"],
color:"#E32500",
background: "#FFD017"
},
Rain: {
title: "It's Raining",
subtitle: "You guessed it",
highlight: ["Raining"],
color:"#004A96",
background:"#2F343A"
},
Thunderstorm: {
title: "Not Just Raining, It's Storming",
subtitle: "Free shower",
highlight: ["Storming"],
color:"#FBFF46",
background:"#020202"
},
Clouds: {
title: "Clouds for Days",
subtitle: "Cotton candy skies",
highlight: ["Days"],
color:"#0044FF",
background: "#939393"
},
Snow: {
title: "Oh Yeah Bud. It's Snowin'",
subtitle: "Make a snow angel bud",
highlight: ["Snowin'"],
color:"#021D4C",
background:"#15A678"
},
Drizzle: {
title: "Just a Wee Ol' Drizzle Lads",
subtitle: "Free shower",
highlight: ["Wee", "Ol'"],
color:"#dbdbdb",
background:"#1FBB68"
},
}
class App extends Component {
componentWillMount() {
this.state = {
temp: 0,
weather: 'Default'
}
}
componentDidMount() {
this.getLocation()
}
getLocation() {
navigator.geolocation.getCurrentPosition(
posData => fetchWeather(posData.coords.latitude,posData.coords.longitude)
.then(res => this.setState({
temp:Math.round(res.temp),
weather: res.weather
})),
error => alert(error),
{timeout: 10000}
)
}
render(){
console.log(this.state.weather)
return(
<View style={[styles.container, {backgroundColor: phrases[this.state.weather].background}]}>
<StatusBar hidden={true}/>
<View style={styles.header}>
<Icon name={iconNames[this.state.weather]} size={80} color={'white'}/>
<Text style={styles.temp}>{this.state.temp}°</Text>
</View>
<View style={styles.body}>
<Highlight
style={styles.title}
highlightStyle={{color: phrases[this.state.weather].color}}
searchWords={phrases[this.state.weather].highlight}
textToHighlight={phrases[this.state.weather].title}
/>
<Text style={styles.subtitle}>{phrases[this.state.weather].subtitle}</Text>
</View>
</View>
)
}
}
const styles = StyleSheet.create({
container: {
flex:1,
backgroundColor:'#FFD017'
},
header: {
flexDirection:'row',
alignItems:'center',
justifyContent:'space-around',
flex:1,
},
temp: {
fontFamily: 'HelveticaNeue-Bold',
fontSize: 45,
color:'white'
},
body: {
alignItems:'flex-start',
justifyContent:'flex-end',
flex:5,
margin:10
},
title: {
fontFamily: 'HelveticaNeue-Bold',
fontSize: 90,
color:'white',
marginBottom:5
},
subtitle: {
fontFamily: 'HelveticaNeue-Medium',
fontSize: 16,
color:'white'
}
});
AppRegistry.registerComponent('IsItRaining', () => App)
fetch
API不包含任何进度回调 ,因此您的选项要么使用在React Native中完全支持的XMLHttpRequest ,要么是基本上将在其上构建的库。 例如,您可以修改fetchWeather
函数来执行以下操作:
export const fetchWeather = (lat,lon, progress) => {
return new Promise((resolve, reject) => {
const url = rootUrl+'&lat='+lat+'&lon='+lon+"&units=metric"
console.log(url)
var oReq = new XMLHttpRequest();
oReq.addEventListener("progress", progress);
oReq.open('GET', url);
oReq.send();
oReq.onreadystatechange = function() {
if (oReq.readyState == XMLHttpRequest.DONE) {
let data = JSON.parse(oReq.responseText);
resolve({temp: data.main.temp, weather: json.weather[0].main});
}
}
});
}
进度是一个回调状态,您可以在其中更新状态。 例如,在您的组件中,添加以下函数:
function updateProgress (oEvent) {
if (oEvent.lengthComputable) {
var progress = oEvent.loaded / oEvent.total;
this.setState({progress})
} else {
// Unable to compute progress information since the total size is unknown
}
}
然后,呼叫变为:
fetchWeather(posData.coords.latitude,posData.coords.longitude, this.updateProgress.bind(this)) fetchWeather(posData.coords.latitude,posData.coords.longitude)
该示例改编自MDN 。
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