The easiest way to use Jackrabbit is to download a binary release, but if you want to access the latest development version, you need to get the Jackrabbit sources and build them using the Maven 3 build environment.
The source tree is divided in standard parts: trunk, branches, tags and commons (more info about commons). The latest development version is found within trunk, while the other parts are used to keep track of the source code of the Jackrabbit releases.
The trunk contains the top-level build environment and a number of component projects within subdirectories. See the README.txt files within each subdirectory for a brief description of the component project. There is also a sandbox directory with miscellaneous contributions that are not yet a part of the official Jackrabbit releases.
You need a Subversion client to access the Jackrabbit source repository. Take a look at the Subversion client list unless you already have a one installed. Once you have the Subversion client installed you can checkout the main Jackrabbit source tree with the following command or its equivalent in the client you are using:
svn checkout http://svn.apache.org/repos/asf/jackrabbit/trunk jackrabbit
The above checkout will create a subdirectory named jackrabbit that contains the latest Jackrabbit sources. See the Subversion book or the documentation of your Subversion client for more information on how to manage your source tree and keep it up to date with latest development.
Jackrabbit uses Maven 3 as the build system and the component sources are mostly organized according to the Maven Standard Directory Layout. The standard build environment is Maven 3 with the Java Development Kit (JDK) 1.6 (but the build is known to work also with Java 7 and 8).
The standard build environment for 1.x versions is Maven 2 with the Java Development Kit (JDK) 1.4 (but the build is known to work also with Java 5 and 6).
See the Running Maven page and the related documentation on the Maven web site for instructions on how to use Maven. You may also want to check for Maven integration with your favourite Integrated Development Environment (IDE).
There are Maven project descriptors (POMs) within both the top level jackrabbit directory you checked out above and all the jackrabbit-something component subdirectories. The easiest way to build Jackrabbit is to use the “multimodule” setup within the top level directory:
$ cd /path/to/jackrabbit; mvn install
This will build and package all the component projects and place the resulting artifacts within your local Maven repository. You can also find the artifacts within the created target subdirectories of the component projects.