zsoltm / jackson-dataformat-bencode

Jackson extension for adding support for reading and writing Bencode formatted data.

Overview

This project contains Jackson extension component for reading and writing Bencode encoded data, either as "raw" data (sequence of String arrays), or via data binding to/from Java Objects (POJOs).

The primary objective of this project is to take advantage of Jackson's easy to use and fast object mapper, and make serializing and de-serializing Bencoded content pussible using either full data-binding or streaming (tree model is not supported yet).

Project is licensed under Apache License 2.0.

Usage

As it is a data type extension to Jackson, it could be used like the usual JSON data format.

Given the following Bencoded data - identical counterpart of JSON example, used as a data binding example in Jackson in 5 minutes tutorial (please note that actual binary data replaced with asterisks, as Bencode format has raw binary representation):

d6:gender4:MALE4:named5:first3:Joe4:last7:Sixpacke9:userImage5:*****8:verified5:falsee

It could be turned into a Java POJO with the following code:

ObjectMapper mapper = new BEncodeMapper();
User u = mapper.readValue(new File("user.bencode"), User.class)

Or similarly a Java POJO could be turned into a Bencoded stream:

mapper.writeValue(new File("user.bencode"), u);

Where the user class used above is a simple POJO:

public class User {
    public enum Gender { MALE, FEMALE }

    public static class Name {
        private String first, last;

        public String getFirst() { return first; }
        public String getLast() { return last; }

        public void setFirst(String s) { first = s; }
        public void setLast(String s) { last = s; }
    }

    private Gender gender;
    private Name name;
    private boolean isVerified;
    private byte[] userImage;

    public Name getName() { return name; }
    public boolean isVerified() { return isVerified; }
    public Gender getGender() { return gender; }
    public byte[] getUserImage() { return userImage; }

    public void setName(Name n) { name = n; }
    public void setVerified(boolean b) { isVerified = b; }
    public void setGender(Gender g) { gender = g; }
    public void setUserImage(byte[] b) { userImage = b; }
}

Of course the POJOs could be decorated with the usual Jackson annotations like @JsonProperty. There is a more complex class within tests, com.fasterxml.jackson.dataformat.bencode.types.Torrent, which represents a complete BitTorent file.

Status

Initial release with decent unit test coverage. Ready to use, but might develop some unexpected surprises.

Next steps:

• Add benchmarks, optimize to reach a level where this is as fast as JSON - theoretically it should be, cause Bencode is simpler than JSON.
• Add proper encoding support; currently UTF-8 is hardwired as default.
• Add some useful features.