If the port needs a Java™ Development Kit (JDK™) to either build, run or even extract the distfile, then define USE_JAVA.

There are several JDKs in the ports collection, from various vendors, and in several versions. If the port must use a particular version, specify it using the JAVA_VERSION variable. The most current version is java/openjdk15, with java/openjdk14, java/openjdk13, java/openjdk12, java/openjdk11, java/openjdk8, and java/openjdk7 also available.

Below is the list of all settings a port will receive after setting USE_JAVA:

Use the java-debug make target to get information for debugging the port. It will display the value of many of the previously listed variables.

Additionally, these constants are defined so all Java ports may be installed in a consistent way:

The related entries are defined in both PLIST_SUB (documented in Section 8.1, “Changing pkg-plist Based on Make Variables”) and SUB_LIST.

When the port is to be built using Apache Ant, it has to define USE_ANT. Ant is thus considered to be the sub-make command. When no do-build target is defined by the port, a default one will be set that runs Ant according to MAKE_ENV, MAKE_ARGS and ALL_TARGET. This is similar to the USES= gmake mechanism, which is documented in Section 6.5, “Building Mechanisms”.

When porting a Java library, the port has to install the JAR file(s) in ${JAVAJARDIR}, and everything else under ${JAVASHAREDIR}/${PORTNAME} (except for the documentation, see below). To reduce the packing file size, reference the JAR file(s) directly in the Makefile. Use this statement (where myport.jar is the name of the JAR file installed as part of the port):

PLIST_FILES+=	${JAVAJARDIR}/myport.jar

When porting a Java application, the port usually installs everything under a single directory (including its JAR dependencies). The use of ${JAVASHAREDIR}/${PORTNAME} is strongly encouraged in this regard. It is up the porter to decide whether the port installs the additional JAR dependencies under this directory or uses the already installed ones (from ${JAVAJARDIR}).

When porting a Java™ application that requires an application server such as www/tomcat7 to run the service, it is quite common for a vendor to distribute a .war. A .war is a Web application ARchive and is extracted when called by the application. Avoid adding a .war to pkg-plist. It is not considered best practice. An application server will expand war archive, but not clean it up properly if the port is removed. A more desirable way of working with this file is to extract the archive, then install the files, and lastly add these files to pkg-plist.

TOMCATDIR=	${LOCALBASE}/apache-tomcat-7.0
WEBAPPDIR=	myapplication

post-extract:
	@${MKDIR} ${WRKDIR}/${PORTDIRNAME}
	@${TAR} xf ${WRKDIR}/myapplication.war -C ${WRKDIR}/${PORTDIRNAME}

do-install:
	cd ${WRKDIR} && \
	${INSTALL} -d -o ${WWWOWN} -g ${WWWGRP} ${TOMCATDIR}/webapps/${PORTDIRNAME}
	cd ${WRKDIR}/${PORTDIRNAME} && ${COPYTREE_SHARE} \* ${WEBAPPDIR}/${PORTDIRNAME}

Regardless of the type of port (library or application), the additional documentation is installed in the same location as for any other port. The Javadoc tool is known to produce a different set of files depending on the version of the JDK that is used. For ports that do not enforce the use of a particular JDK, it is therefore a complex task to specify the packing list (pkg-plist). This is one reason why porters are strongly encouraged to use PORTDOCS. Moreover, even if the set of files that will be generated by javadoc can be predicted, the size of the resulting pkg-plist advocates for the use of PORTDOCS.

The default value for DATADIR is ${PREFIX}/share/${PORTNAME}. It is a good idea to override DATADIR to ${JAVASHAREDIR}/${PORTNAME} for Java ports. Indeed, DATADIR is automatically added to PLIST_SUB (documented in Section 8.1, “Changing pkg-plist Based on Make Variables”) so use %%DATADIR%% directly in pkg-plist.

As for the choice of building Java ports from source or directly installing them from a binary distribution, there is no defined policy at the time of writing. However, people from the FreeBSD Java Project encourage porters to have their ports built from source whenever it is a trivial task.

All the features that have been presented in this section are implemented in bsd.java.mk. If the port needs more sophisticated Java support, please first have a look at the bsd.java.mk Subversion log as it usually takes some time to document the latest features. Then, if the needed support that is lacking would be beneficial to many other Java ports, feel free to discuss it on the FreeBSD Java Language mailing list.

Although there is a java category for PRs, it refers to the JDK porting effort from the FreeBSD Java project. Therefore, submit the Java port in the ports category as for any other port, unless the issue is related to either a JDK implementation or bsd.java.mk.

Similarly, there is a defined policy regarding the CATEGORIES of a Java port, which is detailed in Section 5.3, “Categorization”.