Accessing Maven Pom Variables From Properties File

Question

I am developing a custom maven plugin. When I write:

${project.version}

into my pom file I can get its value however is there a way if I write into a properties file:

project.version = ${project.version}

that will set the project.version value correctly, how can I implement it at my Java code?

PS: I don't use annotations at my Mojo and I don't want to use variables at my Java code because user should define as my variables as at a properties file and I can not change my core Java code in order to changed things.

Answer 1

You can use Maven resource filtering by simply adding <resources> inside <build> and turning on filtering for anything you want.

Answer 2

You may read and save any property in your pom.xml as i do in this function:

/**
 * Save a property in a pom.xml
 *
 * @param propertyName Name of the property
 * @param value New value for the property
 */
public static void saveProjectProperty(String propertyName, String value)
{
    Model model = null;
    FileReader reader = null;
    MavenXpp3Reader mavenreader = new MavenXpp3Reader();
    try
    {
        reader = new FileReader("pom.xml");
        model = mavenreader.read(reader);
        MavenProject project = new MavenProject(model);
        while (project.getParent() != null)
        {
            project = project.getParent();
        }
        project.getProperties().put(propertyName, value);
        try (FileWriter fileWriter = new FileWriter("pom.xml"))
        {
            project.writeModel(fileWriter);
        }
    }
    catch (IOException ex)
    {
        LOG.severe("Error saving pom.xml");
    }
    catch (XmlPullParserException ex)
    {
        LOG.warning("Error reading pom.xml");
    }
}

To be able to use the clases not native in the JVM you should add these dependencies:

<dependency>
  <groupId>org.apache.maven</groupId>
  <artifactId>maven-model</artifactId>
  <version>2.0</version>
</dependency>

<dependency>
  <groupId>org.apache.maven</groupId>
  <artifactId>maven-project</artifactId>
  <version>2.0</version>
</dependency

Answer 3

within your mojo if using annotations see http://maven.apache.org/plugin-tools/maven-plugin-plugin/examples/using-annotations.html use

@Component
protected MavenProject project;

with doclet

/**
 * The Maven project to act upon.
 * 
 * @parameter expression="${project}"
 * @required
 */
private MavenProject project;

then project.getVersion()