Problems of popular approaches
Most of the answers you'll find around the internet will suggest you to either install the dependency to your local repository or specify a "system" scope in the pom
and distribute the dependency with the source of your project. But both of these solutions are actually flawed.
Why you shouldn't apply the "Install to Local Repo" approach
When you install a dependency to your local repository it remains there. Your distribution artifact will do fine as long as it has access to this repository. The problem is in most cases this repository will reside on your local machine, so there'll be no way to resolve this dependency on any other machine. Clearly making your artifact depend on a specific machine is not a way to handle things. Otherwise this dependency will have to be locally installed on every machine working with that project which is not any better.
Why you shouldn't apply the "System Scope" approach
The jars you depend on with the "System Scope" approach neither get installed to any repository or attached to your target packages. That's why your distribution package won't have a way to resolve that dependency when used. That I believe was the reason why the use of system scope even got deprecated. Anyway you don't want to rely on a deprecated feature.
The static in-project repository solution
After putting this in your pom
:
<repository>
<id>repo</id>
<releases>
<enabled>true</enabled>
<checksumPolicy>ignore</checksumPolicy>
</releases>
<snapshots>
<enabled>false</enabled>
</snapshots>
<url>file://${project.basedir}/repo</url>
</repository>
for each artifact with a group id of form x.y.z
Maven will include the following location inside your project dir in its search for artifacts:
repo/
| - x/
| | - y/
| | | - z/
| | | | - ${artifactId}/
| | | | | - ${version}/
| | | | | | - ${artifactId}-${version}.jar
To elaborate more on this you can read this blog post.
Use Maven to install to project repo
Instead of creating this structure by hand I recommend to use a Maven plugin to install your jars as artifacts. So, to install an artifact to an in-project repository under repo
folder execute:
mvn install:install-file -DlocalRepositoryPath=repo -DcreateChecksum=true -Dpackaging=jar -Dfile=[your-jar] -DgroupId=[...] -DartifactId=[...] -Dversion=[...]
If you'll choose this approach you'll be able to simplify the repository declaration in pom
to:
<repository>
<id>repo</id>
<url>file://${project.basedir}/repo</url>
</repository>
A helper script
Since executing installation command for each lib is kinda annoying and definitely error prone, I've created a utility script which automatically installs all the jars from a lib
folder to a project repository, while automatically resolving all metadata (groupId, artifactId and etc.) from names of files. The script also prints out the dependencies xml for you to copy-paste in your pom
.
Include the dependencies in your target package
When you'll have your in-project repository created you'll have solved a problem of distributing the dependencies of the project with its source, but since then your project's target artifact will depend on non-published jars, so when you'll install it to a repository it will have unresolvable dependencies.
To beat this problem I suggest to include these dependencies in your target package. This you can do with either the Assembly Plugin or better with the OneJar Plugin. The official documentaion on OneJar is easy to grasp.
Here's how to build a jar with IntelliJ 10 http://blogs.jetbrains.com/idea/2010/08/quickly-create-jar-artifact/
File -> Project Structure -> Project Settings -> Artifacts -> Click green plus sign -> Jar -> From modules with dependencies...
The above sets the "skeleton" to where the jar will be saved to. To actually build and save it do the following:
Extract to the target Jar
OK
Build | Build Artifact | Build
Try Extracting the .jar file from
ProjectName | out | artifacts | ProjectName_jar | ProjectName.jar
Best Answer
I found the answer via some more searching on the web.
Generally, there are three ways to share resources in a multi module Maven project:
Here's a blog post from Sonatype, the company behind Maven, on sharing resources across projects in Maven, and it is the exact answer I need:
http://www.sonatype.com/people/2008/04/how-to-share-resources-across-projects-in-maven/