查看React Native FS,特别是downloadFile:
上的文档
https://github.com/johanneslumpe/react-native-fs#downloadfileoptions-downloadfileoptions--jobid-number-promise-promisedownloadresult-
下面是一个有效的例子:
import React, { Component } from 'react';
import {
AppRegistry,
Text,
View,
Image,
} from 'react-native';
import RNFS from 'react-native-fs';
export default class downloadFile extends Component {
constructor() {
super()
this.state = {
isDone: false,
};
this.onDownloadImagePress = this.onDownloadImagePress.bind(this);
}
onDownloadImagePress() {
RNFS.downloadFile({
fromUrl: 'https://facebook.github.io/react-native/img/header_logo.png',
toFile: `${RNFS.DocumentDirectoryPath}/react-native.png`,
}).promise.then((r) => {
this.setState({ isDone: true })
});
}
render() {
const preview = this.state.isDone ? (<View>
<Image style={{
width: 100,
height: 100,
backgroundColor: 'black',
}}
source={{
uri: `file://${RNFS.DocumentDirectoryPath}/react-native.png`,
scale: 1
}}
/>
<Text>{`file://${RNFS.DocumentDirectoryPath}/react-native.png`}</Text>
</View>
) : null;
return (
<View>
<Text onPress={this.onDownloadImagePress}>Download Image</Text>
{preview}
</View>
);
}
}
AppRegistry.registerComponent('downloadFile', () => downloadFile);
重要的是要知道height
和width
必须设置在Image
上