resumable_downloader #

resumable_downloader is a lightweight yet powerful download manager for Flutter. It supports:

✅ Resumable downloads using HTTP Range headers
✅ Concurrent and queued download handling
✅ File existence strategies (keepExisting, resume, replace, fail)
✅ Download progress updates and cancelation support
✅ Full control using Dio, custom directory setup, and retry handling

Built for flexibility, designed for scalability.

Features #

• Concurrent Downloading
  Support for downloading multiple files at once with efficient management of concurrent tasks.

• Resumable Downloads
  Built-in support for resuming interrupted downloads, allowing downloads to continue from where they left off rather than starting over.

• Download Progress Reporting
  Track and report download progress with real-time updates via a progress stream. The stream emits progress values between 0.0 (0%) and 1.0 (100%).

• File Existence Handling
  Configurable strategies for handling existing files (e.g., skip, overwrite, or resume from the last known state).

• Flexible Logging
  Optionally capture and log detailed information about each download, including errors and progress, with customizable log levels (e.g., info, warning, error).

• Customizable Retry Logic
  Automatically retries failed downloads based on configurable retry parameters such as maximum retries and delay between attempts.

• Cancel Downloads
  Easy cancellation of ongoing downloads, giving full control to the user.

• Optional Callback for Progress
  Provides an optional callback function that allows users to track the download progress for each file in the queue.

• Cross-Platform Support
  Works seamlessly across all platforms supported by Dart/Flutter, including mobile and desktop applications.

• Optimized for Performance
  Efficiently handles multiple concurrent downloads while minimizing memory and CPU usage.

Getting started #

To get started with the resumable_downloader package, follow these steps:

Prerequisites #

1. Dart 2.12 or later is required. Ensure you have the latest version of Dart installed on your system.
2. Flutter (optional, but supported).
3. Internet access to download files.

Installation #

To install the package, add the following to your pubspec.yaml file:

dependencies:
  resumable_downloader: <latest>

Then, run the following command in your project directory to fetch the package:

flutter pub get

Usage #

• Import the package in your Dart code:

import 'package:resumable_downloader/resumable_downloader.dart';

• Create an instance of DownloadManager:

final DownloadManager _downloadManager = DownloadManager(
    subDir: AppDefaults.downloadSubDir,
    fileExistsStrategy: FileExistsStrategy.resume, // optional
    baseDirectory: await getApplicationDocumentsDirectory(), // optional
    maxConcurrentDownloads: 3, // optional
    maxRetries: 3, // optional
    delayBetweenRetries: Duration.zero, // optional
    logger: (logRecord) { // optional
      logger.log(switch (logRecord.level) {
        LogLevel.debug => Level.debug,
        LogLevel.error => Level.error,
        LogLevel.warning => Level.warning,
        LogLevel.info => Level.info,
        // ignore: require_trailing_commas
      }, 'Download: ${logRecord.message}');
    },
  );

• Call the getFile, addToQueue, addAllToQueue method with the URL of the file you want to download and optional callbacks to handle progress and completion:

// Download immediately or enqueue with callback
_downloadManager.getFile((
  url: downloadUrl,
  progress: (record) {
    print('Progress for ${record.url}: ${record.progressStream}');
  },
));

// Add one item to queue
_downloadManager.addToQueue((
  url: downloadUrl,
  progress: (record) {
    print('Progress for ${record.url}');
  },
));

// Add multiple items to the queue
_downloadManager.addAllToQueue([
  (
    url: 'https://example.com/file1.zip',
    progress: (record) {
      print('File 1 progress...');
    },
  ),
  (
    url: 'https://example.com/file2.zip',
    progress: (record) {
      print('File 2 progress...');
    },
  ),
]);

Additional information #

This is a straightforward, practical guide for users to get started with the package.

Troubleshooting #

• Ensure the download URL is valid and supports Range headers.
• Progress won’t emit unless the server provides a valid Content-Length.
• Check logs for any errors using your provided logger.