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

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?

What have you tried to achieve your wanted results? What has your research concerning your problem shown? Can you provide code of your tries? [How do I ask a good question](https://stackoverflow.com/help/how-to-ask), [How much research effort is expected](https://meta.stackoverflow.com/questions/261592/how-much-research-effort-is-expected-of-stack-overflow-users) and [How to create a Minimal, Complete, and Verifiable example](https://stackoverflow.com/help/mcve) might be helpful to improve your question. — Geshode, Jan 19 '18 at 01:42
This is a little strange... Why are you downloading a zip that contains your dependency? Can't you just put the dependency inside the dependencies list? — R. Karlus, Jan 19 '18 at 01:57
In the zip file there is a .dll file that is needed by the jar in order to run. I agree that it would be nice to just add the jar as a dependency in the dependency list. — Trogdor, Jan 19 '18 at 03:02

score 0 · Answer 1 · edited Jan 29 '19 at 21:56

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.

score 0 · Answer 2 · answered Jan 19 '18 at 12:38

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

score 0 · Answer 3 · answered Feb 14 '18 at 00:21

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>

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

3 Answers3