Commons DBUtils uses Maven or Ant as a build system.
To build a jar file, change into DBUtils's root directory and run maven package. The result will be in the "target" subdirectory.
maven package
To build the Javadocs, run maven javadoc:javadoc. The result will be in "target/docs/apidocs".
maven javadoc:javadoc
To build the full website, run maven site. The result will be in "target/docs".
maven site
Further details can be found in the commons build instructions.