How to share a filtered resource at generate-sources phase in a multi module project? - maven

Question

I have a parent project with 3 child projects:
parent
project-1
/src/main/resources/config.xml
project-2
/src/main/resources/config.xml
project-3
/src/main/resources/config.xml
The configuration config.xml is used during the generate-sources phase. For the three projects, the config.xml is exactly the same. However, the usage of this config.xml is different for each project.
In project-X, I am referring to config.xml as following:
<build>
<plugins>
<plugin>
<groupId>some-group</groupId>
<artifactId>some-artifact</artifactId>
<executions>
<execution>
<goals>
<goal>some-goal</goal>
</goals>
<configuration>
<input>src/main/resources/config.xml</input>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
What is the best way to share this common config.xml between all 3 projects?

Answer 1

You can use the build-helper-maven-plugin here.
PROJECT STRUCTURE
shared-resources-project
+-src
+-main
+-resources
`config.xml
+-project-A
`pom.xml
+-project-B
`pom.xml
+-project-C
`pom.xml
`pom.xml
shared-resources-project/pom.xml
<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>my</groupId>
<artifactId>shared-resources-project</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>pom</packaging>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<modules>
<module>project-A</module>
<module>project-B</module>
<module>project-C</module>
</modules>
<build>
<plugins>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>build-helper-maven-plugin</artifactId>
<version>1.10</version>
<executions>
<execution>
<id>add-resource</id>
<phase>generate-sources</phase>
<goals>
<goal>add-resource</goal>
</goals>
<configuration>
<resources>
<resource>
<filtering>true</filtering>
<directory>${project.parent.basedir}/src/main/resources</directory>
<includes>
<include>config.xml</include>
</includes>
</resource>
</resources>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>some-group</groupId>
<artifactId>some-artifact</artifactId>
<executions>
<execution>
<id>some-plugin-job</id>
<phase>generate-sources</phase>
<goals>
<goal>some-goal</goal>
</goals>
<configuration>
<input>${project.build.outputDirectory}/config.xml</input>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
shared-resources-project/src/main/resources/config.xml
<config>
<parameter>${custom-value}</parameter>
</config>
project-X/pom.xml
<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>
<parent>
<groupId>my</groupId>
<artifactId>shared-resources-project</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<artifactId>project-X</artifactId>
<properties>
<custom-value>Project-X Value</custom-value>
</properties>
</project>
Now, let's build the project:
D:\workspaces> cd shared-resources-project
D:\workspaces\java\shared-resources-project> mvn clean install
Some notes:
The build-helper-maven-plugin will add the common config.xml file as a resource to Project-X.
Then the Maven resources plugin (MRP) will copy config.xml to the project output directory (target directory by default). During the copy, MRP will also replace ${custom-value} with the specific value provided by Project-X.
The final config.xml will be available to another plugin as long as the other plugin is bound to the generate-source phase AND its declaration appears AFTER the build-helper-maven-plugin declaration. Maven (3.0.4+ at least) calls the plugins in their order of apparition in the pom.xml.