从bytes文件创建Zip文件Flutter web

Question

我使用firebase云存储来存储一些文件，然后，我必须把它们放在zip文件中并下载它，我必须这样做ONLY在网络上，这是最难的部分。我现在是这样做的:

FloatingActionButton(
child: const Icon(Icons.download),
onPressed: () async {
List<int>? bytes;
webarc.ZipEncoder encoder = webarc.ZipEncoder();
webarc.Archive archive = webarc.Archive();
try {
List<String> links = await Database.formLinks();
for (String link in links) {
String fileName = link.substring(link.lastIndexOf('/') + 1);
http.Response response = await http.get(
Uri.parse(link),
headers: headers,
);
webarc.ArchiveFile file = webarc.ArchiveFile.stream(
fileName,
response.bodyBytes.elementSizeInBytes,
response.bodyBytes.toList(),
);
archive.addFile(file);
}
webarc.OutputStream outputStream = webarc.OutputStream(
byteOrder: webarc.LITTLE_ENDIAN,
);
bytes = encoder.encode(
archive,
level: webarc.Deflate.BEST_COMPRESSION,
modified: DateTime.now(),
output: outputStream,
);
} catch (e) {
print(e);
Fluttertoast.showToast(
msg: 'Errore nel download dello zip.',
toastLength: Toast.LENGTH_LONG,
gravity: ToastGravity.BOTTOM,
);
return;
}
if (bytes == null) {
Fluttertoast.showToast(
msg: 'Errore nel download dello zip. bytes nulli.',
toastLength: Toast.LENGTH_LONG,
gravity: ToastGravity.BOTTOM,
);
return;
}
String zipFileName = 'forms.zip';
await FileSaver.instance.saveFile(
zipFileName,
Uint8List.fromList(bytes),
'zip',
mimeType: MimeType.ZIP,
);
Fluttertoast.showToast(
msg: 'Zip downloadato correttamente.',
toastLength: Toast.LENGTH_LONG,
gravity: ToastGravity.BOTTOM,
);
},
),

一切都很完美，除了我下载了压缩文件，但是压缩文件是空的。

我尝试这样做在许多不同的方式，下载它与html包，锚定和点击一个div，但现在我认为，包不工作，我怎么能做到这一点?任何帮助都将被接受，谢谢。

注:这是数据库。formLinks功能:

static Future<List<Reference>> getCompiledForms() async =>
(await formsRef.listAll()).items;
static Future<List<String>> formLinks() async {
final List<Reference> forms = await getCompiledForms();
final List<String> links = [];
for (final form in forms) {
String url = await form.getDownloadURL();
links.add(url);
}
return links;

}
这些是我在这些函数中使用的包:

archive: ^3.1.2 (As webarc)

http: ^0.13.3 (as http)

file_saver: ^ 0.0.10

fluttertoast: ^ 8.0.7

cloud_firestore: ^ tripwire

Answer 1

本周我遇到了一个类似的问题，并且能够找出问题所在。我使用html下载使用锚点。点击()方法。

以zip形式下载文件方法以字符串形式输入文件名列表，以Uint8List形式输入文件数据列表。

试试这个，让我知道这是否适合你!

_downloadFilesAsZIP(context, List<String> filenames, files) {
var encoder = ZipEncoder();
var archive = Archive();
ArchiveFile archiveFiles = ArchiveFile.stream(
filenames[0].toString(),
files[0].lengthInBytes,
files[0],
);
print(archiveFiles);
archive.addFile(archiveFiles);
var outputStream = OutputStream(
byteOrder: LITTLE_ENDIAN,
);
var bytes = encoder.encode(archive,
level: Deflate.BEST_COMPRESSION, output: outputStream);
print(bytes);
downloadFile("out.zip", bytes);
}
downloadFile(String fileName, Uint8List bytes) {
final blob = html.Blob([bytes]);
final url = html.Url.createObjectUrlFromBlob(blob);
final anchor = html.document.createElement('a') as html.AnchorElement
..href = url
..style.display = 'none'
..download = fileName;
html.document.body.children.add(anchor);
// download
anchor.click();
// cleanup
html.document.body.children.remove(anchor);
html.Url.revokeObjectUrl(url);
}