There are several ways to download the JAR of this project.
The preferred way to obtain this artifact is through dependency management. It is available, along with its sources and Javadoc JARs, in the Maven Central repository. See the dependency information report for further integration details for your build tool of choice.
Alternatively, you can obtain a binary distribution with all JARs plus the entire site for offline browsing from the project's SourceForge.net Files directory.
If you rather prefer building from source you either have to check out a working copy from the project's public Subversion repository, or download a source tarball from the SourceForge.net Files directory.
After you have obtained the source code, navigate to the source code directory and type mvn install. Prior to that, make sure that you have at least Maven 3.0.5 and Java 1.7 installed. After successful execution the artifact will be installed to your local repository.