Package com.frostwire.jlibtorrent

Class Entry

java.lang.Object
com.frostwire.jlibtorrent.Entry
public final class Entry extends Object
Variant container for bencoded data structures.

Entry represents a single node in a bencoded hierarchical data structure. Bencoding is the binary encoding format used by BitTorrent for .torrent files, magnet links metadata, DHT messages, and tracker communications. It can encode four types:

  • String: Binary-safe byte sequences
  • Integer: Signed 64-bit numbers
  • List: Ordered sequences of other entries
  • Dictionary: Key-value maps (keys are always strings)

Parsing Bencoded Data: 

 // Parse .torrent file
 byte[] torrentData = Files.readAllBytes(Paths.get("download.torrent"));
 Entry root = Entry.bdecode(torrentData);

 // Or from file directly
 Entry root = Entry.bdecode(new File("download.torrent"));

 // Root is typically a dictionary
 Map<String, Entry> dict = root.dictionary();

 Entry announce = dict.get("announce");
 String trackerUrl = announce.string();

Understanding the Structure: 

 // Bencoded data structure:
 // {
 //   "announce": "http://tracker.example.com:80/announce",
 //   "info": {
 //     "name": "filename.iso",
 //     "piece length": 262144,
 //     "pieces": [binary hash data],
 //     "length": 4294967296
 //   },
 //   "creation date": 1234567890
 // }

 Entry root = Entry.bdecode(torrentData);
 Map<String, Entry> dict = root.dictionary();

 // Strings
 String announce = dict.get("announce").string();

 // Nested dictionaries
 Map<String, Entry> info = dict.get("info").dictionary();
 String name = info.get("name").string();
 long pieceLength = info.get("piece length").integer();

 // Lists (piece hashes are typically a binary string with 20-byte chunks)
 Entry pieces = info.get("pieces");
 String piecesData = pieces.string();

Creating Bencoded Data: 

 // Create from primitive types
 Entry stringEntry = new Entry("hello");
 Entry intEntry = new Entry(42L);

 // Create from Java collections
 List<Object> list = Arrays.asList(
     "item1",
     42,
     new Entry("nested")
 );
 Entry listEntry = Entry.fromList(list);

 // Create nested dictionary
 Map<String, Object> dict = new HashMap<>();
 dict.put("name", "My Torrent");
 dict.put("size", 1000000);
 Entry dictEntry = Entry.fromMap(dict);

Encoding and Converting: 

 Entry entry = Entry.bdecode(torrentData);

 // Get string representation (for debugging)
 String debug = entry.toString();  // Human-readable format

 // Re-encode to bencoded binary
 byte[] bencoded = entry.bencode();
 Files.write(Paths.get("output.torrent"), bencoded);

 // Extract values
 String str = entry.string();      // For string entries
 long num = entry.integer();       // For integer entries
 List<Entry> list = entry.list();     // For list entries
 Map<String, Entry> dict = entry.dictionary(); // For dictionary entries

Common Patterns - DHT Immutable Items: 

 // DHT can store and retrieve bencoded data
 SessionManager sm = ...;
 Sha1Hash key = new Sha1Hash("...");

 // Retrieve immutable DHT item
 Entry item = sm.dhtGetItem(key, timeout);
 if (item != null) {
     System.out.println("DHT item: " + item.toString());

     // If it's a dictionary
     Map<String, Entry> data = item.dictionary();
     for (String k : data.keySet()) {
         System.out.println(k + " = " + data.get(k));
     }
 }

Performance Notes: - Creating from lists/maps involves copying data into bencoded structures - Large files may have corresponding large Entry objects in memory - Consider streaming for very large torrent files

See Also:

  • Constructor Details

    • Entry

      public Entry(com.frostwire.jlibtorrent.swig.entry e)

    • Entry

      public Entry(String s)

    • Entry

      public Entry(long n)

  • Method Details

    • swig

      public com.frostwire.jlibtorrent.swig.entry swig()

    • bencode

      public byte[] bencode()

    • string

      public String string()

    • integer

      public long integer()

    • list

      public List<Entry> list()

    • dictionary

      public Map<String,Entry> dictionary()

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • bdecode

      public static Entry bdecode(byte[] data)

    • bdecode

      public static Entry bdecode(File file) throws IOException
      Throws:
      IOException

    • fromList

      public static Entry fromList(List<?> list)

    • fromMap

      public static Entry fromMap(Map<String,?> map)