This library provides a convenient wrapper around Ant build event notification so that programs can inject themselves into Ant invocation and get notified of what targets/tasks are running with what parameters.
Users would invoke Ant with the -lib path/to/ant-spy.jar -listener AntSpyListener command line option. Note that ANT_ARGS environment variable is a convenient way to insert these arguments without polluting the command line.
Your program implements AntListener and put a META-INF/services entry for your class. This class also needs to be passed to Ant invocation by the -lib option. See a sample code in src/test/java for more details.