Jython is a great language-level tool for executing Python within a JVM. There is a divide, however, between the Python world and the Java world. Jython generally does a good job bridging between the two, but falls short in a few areas, in our opinion. One such way is in compiling Jython source files to Java classes.
Jython uses a tool called jythonc for Java class generation and compilation. This tool executes without any regard to physical directory structure and by default places all generated Java classes into the default package. For a variety of reasons, not providing packages for Java classes is generally frowned upon. To its credit, jythonc does have a flag for providing a package for a generated class, but this package name must be provided -- i.e., it is not inferred from the physical directory structure as is the case for javac .
The maven-jython-plugin attempts to bring jythonc 's behavior a little closer to that of javac 's. This is certainly not warranted in all cases, but for the use case this plugin addresses (integrating Jython classes in a Java project), it makes sense.
Just to clarify, if you have the following file:
$basedir/src/main/jython/com/example/whatever/Program.py
then that file will be compiled as:
com.example.whatever.Program
This is all done without any additional configuration, so you can build hierarchies of Jython source files and be assured that they will be compiled into an appropriate Java package.