To build a jar file, change into Discovery's root directory and run mvn package. The result will be in the "target" subdirectory.
To build the Javadocs, run mvn javadoc:javadoc. The result will be in "target/site/apidocs".
To build the full website, run mvn site. The result will be in "target/site".
Further details can be found in the commons build instructions.
To build a jar file and the javadocs, change into Discovery's root directory and run ant dist. The result will be in the "dist" subdirectory.
Nightly Builds are built once a day from the current SVN HEAD. These are provided purely for test purposes and are NOT official releases of the Apache Software Foundation - Released versions of Commons Discovery are available here.