世博会响应本机，将PDF文件保存到下载文件夹

Question

以下代码对图像文件正确工作。但是，当我试图保存PDF文件或其他非媒体格式时，我无法创建资产错误。

我知道世博媒体库是为处理媒体格式文件而设计的。世博媒体库是否有其他保存其他文件格式的选择？

import * as FileSystem from 'expo-file-system'
import * as Permissions from 'expo-permissions'
import * as MediaLibrary from 'expo-media-library'

const downloadFile = async (uri: string) => {
    const targetUri = FileSystem.documentDirectory + getFileName(uri)

    const downloadedFile = await FileSystem.downloadAsync(uri, targetUri)

    if (downloadedFile.status === 200) {
        if (Platform.OS === 'android') {
            const permission = await Permissions.askAsync(Permissions.MEDIA_LIBRARY)

            if (permission.status !== 'granted') {
                return
            }

            const asset = await MediaLibrary.createAssetAsync(downloadedFile.uri)
            const album = await MediaLibrary.getAlbumAsync('Download')

            await MediaLibrary.addAssetsToAlbumAsync([asset], album, false)
        }
    }
}

Answer 1

它使用https://docs.expo.dev/versions/latest/sdk/filesystem/#storageaccessframeworkcreatefileasyncparenturi-string-filename-string-mimetype-string在android设备上工作。

import * as FileSystem from 'expo-file-system';
import { StorageAccessFramework } from 'expo-file-system';

const permissions = await StorageAccessFramework.requestDirectoryPermissionsAsync();
if (!permissions.granted) {
    return;
}

try {
    await StorageAccessFramework.createFileAsync(permissions.directoryUri, fileName, 'application/pdf')
    .then((r) => {
        console.log(r);
    })
    .catch((e) => {
        console.log(e);
    });
} catch((e) => {
    console.log(e);
});

我的pdf下载得很好！

在我的例子中，我必须从一个base64字符串生成文件。我的代码：

import * as FileSystem from 'expo-file-system';
import { StorageAccessFramework } from 'expo-file-system';

const permissions = await StorageAccessFramework.requestDirectoryPermissionsAsync();
if (!permissions.granted) {
    return;
}

const base64Data = 'my base 64 data';

try {
    await StorageAccessFramework.createFileAsync(permissions.directoryUri, fileName, 'application/pdf')
        .then(async(uri) => {
            await FileSystem.writeAsStringAsync(uri, base64Data, { encoding: FileSystem.EncodingType.Base64 });
        })
        .catch((e) => {
            console.log(e);
        });
} catch (e) {
    throw new Error(e);
}