When you have many sub-projects, or so-called modules, related to a project and you want to organize them efficiently in a single project, you can use Maven multi-module feature.
To enable this feature, you will need to create an empty parent project with no code specified since code will be provided through each module (sub-project).The pom.xml of the parent project should define the packaging type.
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.petehouston.maven</groupId>
<artifactId>multi-module-example</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>pom</packaging>
</project>
In order to add a module, simply create a new Maven project at same level of the parent pom.xml.
The module’s pom.xml should refer to the parent project like following:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>multi-module-example</artifactId>
<groupId>com.petehouston.maven</groupId>
<version>1.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>module-01</artifactId>
</project>
Final step is to let parent project know about its children by specifying the module in the pom.xml:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.petehouston.maven</groupId>
<artifactId>multi-module-example</artifactId>
<version>1.0-SNAPSHOT</version>
<modules>
<module>module01</module>
<module>module02</module>
</modules>
<packaging>pom</packaging>
</project>
Congratulation! You have a working multi-module project now.
