async_zip

Description:

async zip

Asynchronous Zip library #

This package allows fast reading and writing Zip archives asynchronously and
with low memory consumption.
There is already a standard archive library
for Dart. But the standard library has two major issues:

It cannot be used asynchronously
It reads Zip files completely to memory and unpacks them from there. This is
an issue when reading large Zip files on low or medium range devices.

Zip files can be read and written synchronously as well as asynchronously.
Synchronous access may be faster in some situations. Choose whatever you need.
Make sure to call close() in any case after having worked with a Zip file.
You are leaking resources otherwise or risk ending up with an unfinished Zip
file when working with ZipFileWriter and ZipFileWriterSync.
Reading Zip files #
Reading data synchronously #
import 'package:async_zip/async_zip.dart';

final reader = ZipFileReaderSync();
try {
reader.open(File('path-to-archive.zip'));

// Get all Zip entries
final entries = reader.entries();
for (final entry in entries) {
print('${entry.name} ${entry.size}');
}

// Read a specific file
reader.readFile('specific-image.jpg', File('/somewhere/on/disk/image.jpg'));

// Read specific data as Uint8List
final data = reader.readFile('README.md');

} on ZipException catch (ex) {
print('Could not read Zip file: ${$ex.message}');
} finally {
reader.close();
}
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Reading data asynchronously #
import 'package:async_zip/async_zip.dart';

final reader = ZipFileReader();
try {
reader.open(File('path-to-archive.zip'));

// Get all Zip entries
final entries = await reader.entries();
for (final entry in entries) {
print('${entry.name} ${entry.size}');
}

// Read a specific file
await reader.readFile('specific-image.jpg', File('/somewhere/on/disk/image.jpg'));

// Read specific data as Uint8List
final data = await reader.readFile('README.md');

} on ZipException catch (ex) {
print('Could not read Zip file: ${$ex.message}');
} finally {
await reader.close();
}
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Writing Zip files #
Writing data synchronously #
import 'package:async_zip/async_zip.dart';

final reader = ZipFileWriterSync();
try {
reader.create(File('path-to-archive.zip'));

// Write a file to the Zip file
reader.writeFile('image.jpg', File('/somewhere/on/disk/image.jpg'));

// Write Uint8List data to the Zip file
Uint8List data = …; // some binary data
reader.writeData('data.txt', data);

} on ZipException catch (ex) {
print('Could not create Zip file: ${$ex.message}');
} finally {
reader.close();
}
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Write data asynchronously #
import 'package:async_zip/async_zip.dart';

final reader = ZipFileWriter();
try {
await reader.create(File('path-to-archive.zip'));

// Write a file to the Zip file
await reader.writeFile('image.jpg', File('/somewhere/on/disk/image.jpg'));

// Write Uint8List data to the Zip file
Uint8List data = …; // some binary data
await reader.writeData('data.txt', data);

} on ZipException catch (ex) {
print('Could not create Zip file: ${$ex.message}');
} finally {
await reader.close();
}
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Extract a Zip archive to a folder #
Two functions allow extraction of a Zip archive to a folder.
extractZipArchive() works asynchronously, extractZipArchiveSync() works
synchronously. Both can take an optional callback parameter that is called
once for every extracted file (after the file has been copied to the folder).
import 'package:async_zip/async_zip.dart';

final archive = File(…);
final extractTo = Directory(…);
var copied = 0;
var percentage = 0;
await extractZipArchive(archive, extractTo, callback: (entry, totalEntries) {
copied++;
final newPercentage = (copied * 100 / totalEntries).round();
if (newPercentage != percentage) {
percentage = newPercentage;
print('$percentage%');
}
});

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Internals #
This package uses the following C library for reading and writing:
https://github.com/kuba--/zip
The library is integrated using Dart's
foreign function interface (FFI).