Multithreaded File Downloader

Overview

This project is a multithreaded file downloader written in Java. It allows downloading large files efficiently by dividing the file into multiple chunks, downloading them in parallel, and then merging the chunks into a single file.

The project consists of three main components:

1. Merger.java: Handles merging of downloaded chunks into the final file.
2. MultiDownload.java: Represents a runnable task for downloading a specific chunk of the file.
3. MultiDownloader.java: The entry point of the program, orchestrating the download process using multiple threads.

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Files and Their Functions

1. Merger.java

This class handles the merging of individual file chunks into the final output file. It also ensures cleanup of temporary chunk files after merging.

Key Method: mergeChunksIntoFile(String directory, int totalChunks, String outputFile)

• Parameters:
  • directory: Path to the directory containing the chunk files.
  • totalChunks: Total number of chunks to merge.
  • outputFile: Name of the final merged file.
• Process:
  • Opens the output file for writing.
  • Iterates over all chunk files (e.g., part0, part1, etc.).
  • Reads each chunk and writes its contents to the output file.
  • Deletes the chunk file after writing to save space.
• Output: Produces the final merged file and prints a success message.

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2. MultiDownload.java

This class defines a task for downloading a specific range of bytes (a chunk) from the file.

Constructor:

public MultiDownload(URL resourceUrl, long rangeStart, long rangeEnd, int chunkIndex, String downloadDirectory)