Maven - How to extract a dependency inside another ZIP dependency? - maven

Question

I have a maven project.
Inside that project, I have a .zip dependency that carries a jar and I need to extract that jar out of the zip dependency and have maven use the jar as a dependency. I can currently download and unpack the zip but, cannot figure out a way to add the unpacked jar as a dependency for the project during the build process.
Here is what I'm currently doing for unpacking:
<dependency>
<groupId>com.bar</groupId>
<artifactId>foo</artifactId>
<version>${foo.version}</version>
<type>zip</type>
</dependency>
...
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>unpack</id>
<goals>
<goal>unpack-dependencies</goal>
</goals>
<phase>validate</phase>
<configuration>
<includeGroupIds>com.bar</includeGroupIds>
<includeArtifactIds>foo</includeArtifactIds>
<outputDirectory>${basedir}/target</outputDirectory>
<type>jar</type>
</configuration>
</execution>
</executions>
</plugin>
I read up on some other posts that you could try adding the jar to the class path using this.
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<configuration>
<additionalClasspathElements>
<additionalClasspathElement>${basedir}/target</additionalClasspathElement>
</additionalClasspathElements>
</configuration>
</plugin>
Even doing so I was still unable to reference the packages in foo.jar in my project.
Can someone help me?

Answer 1

For maven to use it without subtly breaking stuff elsewhere, you must install the jar into your local repository.
I would suppose that a combination of unpacking the zip file in target/ and then invoking install:install-file on the resulting jar could do what you need. I asked some years back how to integrate that in a normal build - you might find the answer relevant. Multiple install:install-file in a single pom.xml

Answer 2

Let's assume that, after unpacking the zip, you have foo.jar in your module's target folder: ${project.build.directory}/foo.jar
Having this in place, you can then declare a System Dependency pointing to that jar, e.g.
<dependency>
<groupId>foo</groupId>
<artifactId>foo.jar</artifactId>
<systemPath>${project.build.directory}/foo.jar</systemPath>
</dependency>
Tip: if you dont want to delete/re-download the jar each time you do a clean (some IDE will complain the the jar is not always present) just download it once in the ${project.basedir}.
To download the jar once, you can put your "unpack" execution in a profile that gets activated only when the jar is missing.
<profiles>
<profile>
<activation>
<file>
<missing>${project.basedir}/foo.jar</missing>
</file>
</activation>
...
</profile>
</profiles>

Answer 3

Some time ago, I've faced the same problem. I had a zip file as my dependency, and during the build process I need to extract it and separate the content inside my generated package.
I don't know what are you using to deliver your project, but at that time I've used the maven-antrun-plugin
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-antrun-plugin</artifactId>
<version>2.6</version>
</plugin>
With this, I've used the tag unzip inside my target configuration. As you can see here or here. I just don't recommend you to use the task tag as they're using, you'd better prefer the target tag.
Hope it helps you.