Java Torrent File Parser

A simple Java library for parsing and encoding .torrent files using the Bencode format.

Requirements

• Java 17 or higher
• Maven (for building locally)

Installation

Because this library is not currently published to Maven Central, you will need to install it to your local Maven repository first.

git clone https://github.com/robothaver/JavaTorrentFileParser
cd JavaTorrentFileParser
mvn clean install

Maven:

<dependency>
<groupId>com.robothaver</groupId>
<artifactId>TorrentFileParser</artifactId>
<version>1.2</version>
</dependency>

Features

Parsing

• Parse .torrent files into a TorrentMetadata object
• Parse .torrent files into a Map<String, Object>
• Calculate the info hash
• Support for both single-file and multi-file torrents
• Access optional metadata fields (trackers, comments, creator info, Azureus properties and more)
• Reusable and thread-safe parser

Encoding

• Encode a Map<String, Object> into a Bencoded byte array
• Encode a TorrentMetadata object into a Bencoded byte array
• Reusable and thread-safe encoder

Raw byte and string handling

• If you parse into a TorrentMetadata object, the parser automatically converts known text fields into Java Strings. However, any unrecognized fields placed into the otherValues map will remain as raw byte arrays and must be converted manually.
• If you parse directly to a Map<String, Object>, all string values will remain as byte arrays and require manual conversion.

Usage

Parser usage

publicstaticvoidmain(String[] args) throwsIOException, MalformedTorrentFileException, NoSuchAlgorithmException {
Pathpath = Path.of("Path to torrent file");
byte[] bytes = Files.readAllBytes(path);
Instantstart = Instant.now();
TorrentFileParsertorrentParser = newTorrentFileParserImpl();
// Parse to metadata object// If InfoHashCalculator is provided the info hash will get calculatedTorrentMetadatatorrentMetadata = torrentParser.parseToMetadata(bytes, newInfoHashCalculatorImpl());
// Or use torrentParser.parseToMap() to parse to a mapInstantfinish = Instant.now();
System.out.println(torrentMetadata.getName());
longtimeElapsed = Duration.between(start, finish).toMillis();
System.out.println("Parsing finished in " + timeElapsed + "ms");
}

Note: If you parse to a map and provide an InfoHashCalculator, the calculated info hash will get added to the root of the returned map.

Encoder usage

publicstaticvoidmain(String[] args) throwsNoSuchAlgorithmException, IOException, MalformedTorrentFileException {
Pathpath = Path.of("Path to torrent file");
TorrentFileParserImpltorrentFileParser = newTorrentFileParserImpl();
byte[] fileBytes = Files.readAllBytes(path);
// Encode a map to bencoded byte array (reencode a .torrent file in this example)Map<String, Object> torrentMap = torrentFileParser.parseToMap(fileBytes, null);
TorrentEncoderImpltorrentEncoder = newTorrentEncoderImpl();
byte[] bytes = torrentEncoder.encodeTorrentMap(torrentMap);
// Encode metadata object to bencoded byte arrayTorrentMetadatatorrentMetadata = torrentFileParser.parseToMetadata(fileBytes, null);
byte[] metadataBytes = torrentEncoder.encodeTorrentMetadata(torrentMetadata);
}

TorrentMetadata object structure

publicclassTorrentMetadata {
privatefinalMap<String, Object> otherValues;
privateStringannounce;
privateStringname;
privateLongpieceLength;
privatebooleanisSingleFile;
privatebooleanisPrivate;
privateLongtotalLength;
privatebyte[] pieces;
privatefinalList<TorrentFile> files;
StringinfoHash; // null if no InfoHashCalculator is provided// Optional fieldsprivateList<List<String>> announceList;
privateStringcreator;
privateLongcreationDate;
privateStringsource;
privateStringcomment;
privateStringencoding;
privateMap<String, Object> azureusProperties;
}