Retrieve version from maven pom.xml in code – Dev

The best answers to the question “Retrieve version from maven pom.xml in code” in the category Dev.

QUESTION:

What is the simplest way to retrieve version number from maven’s pom.xml in code, i.e., programatically?

ANSWER:

The accepted answer may be the best and most stable way to get a version number into an application statically, but does not actually answer the original question: How to retrieve the artifact’s version number from pom.xml? Thus, I want to offer an alternative showing how to do it dynamically during runtime:

You can use Maven itself. To be more exact, you can use a Maven library.

<dependency>
  <groupId>org.apache.maven</groupId>
  <artifactId>maven-model</artifactId>
  <version>3.3.9</version>
</dependency>

And then do something like this in Java:

package de.scrum_master.app;

import org.apache.maven.model.Model;
import org.apache.maven.model.io.xpp3.MavenXpp3Reader;
import org.codehaus.plexus.util.xml.pull.XmlPullParserException;

import java.io.FileReader;
import java.io.IOException;

public class Application {
    public static void main(String[] args) throws IOException, XmlPullParserException {
        MavenXpp3Reader reader = new MavenXpp3Reader();
        Model model = reader.read(new FileReader("pom.xml"));
        System.out.println(model.getId());
        System.out.println(model.getGroupId());
        System.out.println(model.getArtifactId());
        System.out.println(model.getVersion());
    }
}

The console log is as follows:

de.scrum-master.stackoverflow:my-artifact:jar:1.0-SNAPSHOT
de.scrum-master.stackoverflow
my-artifact
1.0-SNAPSHOT

Update 2017-10-31: In order to answer Simon Sobisch’s follow-up question I modified the example like this:

package de.scrum_master.app;

import org.apache.maven.model.Model;
import org.apache.maven.model.io.xpp3.MavenXpp3Reader;
import org.codehaus.plexus.util.xml.pull.XmlPullParserException;

import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Application {
  public static void main(String[] args) throws IOException, XmlPullParserException {
    MavenXpp3Reader reader = new MavenXpp3Reader();
    Model model;
    if ((new File("pom.xml")).exists())
      model = reader.read(new FileReader("pom.xml"));
    else
      model = reader.read(
        new InputStreamReader(
          Application.class.getResourceAsStream(
            "/META-INF/maven/de.scrum-master.stackoverflow/aspectj-introduce-method/pom.xml"
          )
        )
      );
    System.out.println(model.getId());
    System.out.println(model.getGroupId());
    System.out.println(model.getArtifactId());
    System.out.println(model.getVersion());
  }
}

ANSWER:

Assuming you’re using Java, you can:

  1. Create a .properties file in (most commonly) your src/main/resources directory (but in step 4 you could tell it to look elsewhere).

  2. Set the value of some property in your .properties file using the standard Maven property for project version:

    foo.bar=${project.version}
    
  3. In your Java code, load the value from the properties file as a resource from the classpath (google for copious examples of how to do this, but here’s an example for starters).

  4. In Maven, enable resource filtering. This will cause Maven to copy that file into your output classes and translate the resource during that copy, interpreting the property. You can find some info here but you mostly just do this in your pom:

    <build>
      <resources>
        <resource>
          <directory>src/main/resources</directory>
          <filtering>true</filtering>
        </resource>
      </resources>   
    </build>
    

You can also get to other standard properties like project.name, project.description, or even arbitrary properties you put in your pom <properties>, etc. Resource filtering, combined with Maven profiles, can give you variable build behavior at build time. When you specify a profile at runtime with -PmyProfile, that can enable properties that then can show up in your build.

ANSWER:

There is also the method described in Easy way to display your apps version number using Maven:

Add this to pom.xml

<build>
  <plugins>
    <plugin>
      <groupId>org.apache.maven.plugins</groupId>
      <artifactId>maven-jar-plugin</artifactId>
      <configuration>
        <archive>
          <manifest>
            <mainClass>test.App</mainClass>
            <addDefaultImplementationEntries>
              true
            </addDefaultImplementationEntries>
          </manifest>
        </archive>
      </configuration>
    </plugin>
  </plugins>
</build>

Then use this:

App.class.getPackage().getImplementationVersion()

I have found this method to be simpler.

ANSWER:

Packaged artifacts contain a META-INF/maven/${groupId}/${artifactId}/pom.properties file which content looks like:

#Generated by Maven
#Sun Feb 21 23:38:24 GMT 2010
version=2.5
groupId=commons-lang
artifactId=commons-lang

Many applications use this file to read the application/jar version at runtime, there is zero setup required.

The only problem with the above approach is that this file is (currently) generated during the package phase and will thus not be present during tests, etc (there is a Jira issue to change this, see MJAR-76). If this is an issue for you, then the approach described by Alex is the way to go.