A Java implementation of bsdiff (http://www.daemonology.net/bsdiff/)
jbsdiff can be used from its command line interface:
java -jar jbsdiff.jar command oldfile newfile patchfile
Where command is either 'diff' or 'patch.' You can also specify the compression algorithm used during a diff operation by setting a system property:
java -Djbsdiff.compressor=gz -jar jbsdiff.jar diff a.bin b.bin patch.gz
Supported compression algorithms (from the Apache Commons Compress library) are bzip2 (the default), gz, pack200, and xz.
...but jbsdiff is mostly intended to be used as a library. See the ui package for usage examples.
To build a jar, run:
./gradlew build