FlashFetch

FlashFetch is a Java package designed for efficient and concurrent file downloading. It provides a simple and intuitive API for managing download tasks, allowing you to add, pause, resume, and cancel downloads with ease. FlashFetch requires JDK 18 or later.

Features

Concurrent Downloads: FlashFetch supports concurrent downloading of multiple files, maximizing the utilization of available network resources.
Multi-part Downloading: Files can be downloaded in multiple parts, improving download speed and reliability, especially for larger files.
Non-blocking Operations: The download tasks run asynchronously, allowing you to continue working with your application while files are being downloaded in the background.
Download Queue Management: Easily add, pause, resume, and cancel download tasks in the queue.
Intuitive API: The package provides a straightforward and user-friendly API for managing downloads.

Architecture

Usage

Getting Started

Obtain an instance of the DownloadManager by calling FetchFlash.getDownloader():

import com.example.flashfetch.FetchFlash;
import com.example.flashfetch.DownloadManager;

DownloadManager downloader = FetchFlash.getDownloader();

Add a new download task to the queue using the addToDownloadQueue method. This method takes three parameters: the URL of the file to download, the output location where the file should be saved, and the desired filename. It returns a Task object representing the download task. java

String url = "https://example.com/file.zip";
String outputLocation = "/path/to/downloads";
String filename = "file.zip";
Task task = downloader.addToDownloadQueue(url, outputLocation, filename);

Controlling Download Tasks

You can control the state of a download task using the following methods:

pauseDownload(int taskId): Pauses the download task with the specified task ID.
resumeDownload(int taskId): Resumes the paused download task with the specified task ID.
cancelDownload(int taskId): Cancels the download task with the specified task ID.

int taskId = task.getTaskId();
downloader.pauseDownload(taskId);
downloader.resumeDownload(taskId);
downloader.cancelDownload(taskId);

Exiting the Application

To gracefully exit the application and cancel all tasks in the download queue, call the exit method on the DownloadManager instance:

downloader.exit();

Handling Download Events

FlashFetch provides a way to handle events related to download tasks, such as progress updates, completion, errors, and exit. To use the event handling feature, you need to create a class that implements the FFListener interface and overrides the respective methods. Then, you can pass your listener to the constructor call.

Example

import com.example.flashfetch.FFListener;
import com.example.flashfetch.ProgressEvent;

class MyDownloadListener implements FFListener {
    @Override
    public void onProgressUpdate(ProgressEvent event) {
    // Handle progress update
        System.out.println("Download progress: " + event.getProgress() + "%");
    }
    
    @Override
    public void onCompleted(ProgressEvent event) {
    // Handle download completion
        System.out.println("Download completed: " + event.getTask().getTaskId());
    }
    
    @Override
    public void onError(ProgressEvent event) {
    // Handle download error
        System.err.println("Download error: " + event.getException().getMessage());
    }
    
    @Override
    public void onExit(ProgressEvent event) {
    // Handle download exit
        System.out.println("Download process exited.");
    }
}

// Register the listener with the DownloadManager
MyDownloadListener listener = new MyDownloadListener();
DownloadManager downloader = new DownloadManager(listener);

The FFListener interface defines the following methods:

onProgressUpdate(ProgressEvent event): This method is called when the download progress is updated, allowing you to handle progress updates for a specific download task. In the example, it prints the current download progress.
onCompleted(ProgressEvent event): This method is called when a download task is completed successfully, enabling you to perform any necessary actions after the download finishes. In the example, it prints the name of the downloaded file.
onError(ProgressEvent event): This method is called when an error occurs during the download process, providing you with the opportunity to handle errors gracefully. In the example, it prints the error message.
onExit(ProgressEvent event): This method is called when the you shutdown download manager or is exited unexpectedly. In the example, it prints a message indicating the download process has exited.

ProgressEvent

The ProgressEvent class encapsulates the information related to a specific event that occurs during the download process. It contains the following fields:

public class ProgressEvent {
   private EventType eventType;
   private final Task task;
   private final float progress;
   private int partIdx = -1; // not set or unavailable
   private String message;
   private Exception exception;
   // ... other methods
}

eventType: An enum representing the type of event (e.g., progress update, completion, error).
task: The Task object associated with the event.
progress: The current download progress represented as a float value between 0 and 100.00.
partIdx: The index of the download part for which the event occurred (if applicable).
message: A message associated with the event (e.g., error message).
exception: An exception object representing any error that occurred during the download process (if applicable).

meiMingle/flashfetch