Are there any decent BitTorrent libraries for Java? I need to program a simple torrent client, but it would be great if I didn't have to write everything from scratch.
Snark by Three Rings is a very lightweight bitorrent library that will give you basic torrent features.
Was originally written by Mark Wielaard. A github source can be found here https://github.com/akerigan/born-again-snark
Turn's TTorrent is a pure Java bit torrent library.
I have created a Bitlet Fork on Github.
It's LGPLed, and it's running faster than ttorent.
Azureus is written in Java - is most likely not "simple" but quite likely "decent" :)
Adding to answer from jjnguy : The code seems to be at http://code.google.com/p/snark/ and not in the repo pointed to in the link you've provided.
I've not used it, but a Google search showed up YAIRCC. Describes itself as "A lightweight Java Bittorrent library and client".
Transdroid and Transdroid-desktop are libraries for adroid, that can also be used in java to control existing torrent clients.
来源：https://stackoverflow.com/questions/944530/java-bittorrent-library