JPA 2.0: Adding entity classes to PersistenceUnit *from different jar* automatically

Question

I have a maven-built CDI-based Java SE app, which has a core module, and other modules.
Core has the persistence.xml and some entities. Modules hav

Answer 1

Possible duplicate, see my SO question.

We faced the same problem and the only way we found was to accumulate all entities in one persistence.xml for the final (web-)application.

At the same time we define separate persistence.xml files in our test resources so we can run acceptance tests per module.

Answer 2

I have a slightly different setup where I am placing persistence.xml in the WAR file but some of its dependencies includes @Entity annotated classed to include in the persistence unit.

I have solved my problem using Maven a bit like Adrian Shum described in #3, but using the element to include the jars to be scanned for @Entity annotations.

I added a property to my-web/pom.xml for each dependency including extra entities. All my jars are part of a Maven multiproject build so for me it looks like.

<properties>
    <common.jar>common-${project.version}.jar</common.jar>
    <foo.jar>foo-${project.version}.jar</foo.jar>
</properties>

I thereafter add the following to the persistence.xml

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0" ... >
    <persistence-unit name="primary">
        <jta-data-source>java:jboss/datasources/mysource</jta-data-source>

        <jar-file>lib/${common.jar}</jar-file>
        <jar-file>lib/${foo.jar}</jar-file>

        ...
    </persistence-unit>
</persistence>

Lastly I configure the maven-resource-plugin in web/pom.xml to replace the $expressions in persistence.xml with the properties set in the POM

<build>
  <resources>
    <resource>
      <directory>src/main/resources</directory>
      <filtering>true</filtering>
      <includes>
        <include>**/persistence.xml</include>
      </includes>
    </resource>
    <resource>
      <directory>src/main/resources</directory>
      <filtering>false</filtering>
      <excludes>
        <exclude>**/persistence.xml</exclude>
      </excludes>
    </resource>
  </resources>
  ...
</build>