How to check and access javadoc/source for Maven Artifacts - plugins

Question

I am writing a Maven plugin which needs to check if a certain project
dependency has javadocs and sources available... and if so, would like
to download them and archive them on a server.
I cannot find out how to check if the javadocs and source are available
or how to access them if they are.
Any help would be appreciated.

Answer 1

You can reference additional artifacts by adding the classifier tag to a dependency. The classifier is the additional part of the artifact's name in the repository, e.g junit-4.5-sources.jar
So to directly declare a dependency on the junit sources jar you can specify it as follows:
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.5</version>
<classifier>sources</classifier>
<scope>test</scope>
</dependency>
If you want to download all the dependency sources, use the maven-dependency-plugin's copy-dependencies goal specifying the classifier sources. The following example defines two executions, one for sources and one for javadocs.
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>sources</id>
<phase>package</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
<configuration>
<classifier>sources</classifier>
<failOnMissingClassifierArtifact>false</failOnMissingClassifierArtifact>
<outputDirectory>${project.build.directory}/sources</outputDirectory>
</configuration>
</execution>
<execution>
<id>javadocs</id>
<phase>package</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
<configuration>
<classifier>javadoc</classifier>
<failOnMissingClassifierArtifact>false</failOnMissingClassifierArtifact>
<outputDirectory>${project.build.directory}/javadocs</outputDirectory>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
If you want to package all the downloaded artifacts into a zip, you can use the maven-assembly-plugin to create an archive of the project. The example below are the contents of an assembly descriptor file to include the sources and javadocs directories:
<assembly>
<id>project</id>
<formats>
<format>zip</format>
</formats>
<fileSets>
<fileSet>
<directory>${project.basedir}</directory>
<useDefaultExcludes>true</useDefaultExcludes>
<includes>
<include>${project.build.directory}/sources</include>
<include>${project.build.directory}/javadocs</include>
</includes>
</fileSet>
</fileSets>
</assembly>
To reference the assembly, add a plugin configuration to your pom. This assumes the above contents have been put in src/main/assembly/sources.xml (make sure it is defined after the dependency configuration above):
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<version>2.2-beta-4</version>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
<configuration>
<descriptors>
<descriptor>src/main/assembly/sources.xml</descriptor>
</descriptors>
</configuration>
</execution>
</executions>
</plugin>