How to use Maven to build a Java EE project with Java class references to several dependent Java projects?

Question

I'm a rookie in Maven and recently I started using Maven to manage our Java EE project. The most important job is to build a project which depends on several other projects for Java classes. Firstly, I found it cannot detect these Java class even though I configured these Java projects as library references in the main project and Deployment Assembly, so I tried another approach. I exported these dependent projects to jars and then created a Maven dependency using the following command line:

mvn install:install-file -DgroupId=MY_GROUP_ID -DartifactId=ARTIFACT_ID -Dversion=1.0.0 -Dpackaging=jar -Dfile=MY_JAR.jar

And then I added these dependencies in the main project's pom.xml, and it absolutely works. But this approach is very hard to popularize among our team members, since it requires manually running a script.

So I'm wondering if there is a plugin for Maven can meet my goal, to build a main project with the project references without exporting dependent projects to jars. I tried to use Modules in pom.xml but It shows error as below:

Project build error: 'packaging' with value 'war' is invalid. Aggregator projects require 'pom' as packaging.

Can anybody help me? Thanks very much.

Answer 1

You are getting this error because you are trying to join everything with maven pom file where packaging node is set to war:

war/
+--- project 1 - jar/
|
+--- project 2 - jar/

instead you have to reorganize your project and join everything in project with packaging type set to "pom"

pom/
+--- war/
|
+--- project 1 - jar/
|
+--- project 2 - jar/

Maven requires parent pom to be of type "pom".