How can I get maven to just print pom coordinates? - maven

Question

I would like maven to parse a pom file for me and just print out the coordinates of the generated artifact(s). Maven is obviously parsing this info, I just want to know how to get it printed and then have maven stop. I want to use this in some shell scripting, and parsing the pom seems onerous to do in bash - especially with all the inheritance implications and dependency coordinates listed throughout. I don't want any building to occur since I may only have the POM, not the source files.
The best way I've found so far is to parse the output of this:
mvn -N dependency:tree
This seems a bit heavy-weight since it parses ALL dependencies. Is there a better way to do this?

Answer 1

You can create a small java programm which exactly does this like the following:
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import org.apache.maven.model.Model;
import org.apache.maven.model.io.xpp3.MavenXpp3Reader;
import org.codehaus.plexus.util.xml.pull.XmlPullParserException;
public class PomRead {
public String getPomVersion(Model model) {
String result = model.getVersion();
if (result == null) {
throw new IllegalArgumentException("The artifact does not define a version.");
}
return result;
}
public Model readModel(InputStream is) throws IOException, XmlPullParserException {
MavenXpp3Reader model = new MavenXpp3Reader();
Model read = model.read(is);
return read;
}
public Model readModel(File file) throws IOException, XmlPullParserException {
FileInputStream fis = new FileInputStream(file);
return readModel(fis);
}
public String getVersionFromPom(File pomFile) throws IOException, XmlPullParserException {
Model model = readModel(pomFile);
return getPomVersion(model);
}
public static void main(String[] args) {
if (args.length != 1) {
System.err.println("Invalid number of arguments.");
System.err.println("");
System.err.println("usage: pom.xml");
return;
}
String pom = args[0];
File pomFile = new File(pom);
if (!pomFile.exists() || !pomFile.isFile() || !pomFile.canRead()) {
System.err.println("File " + pomFile + " can not be accessed or does not exist.");
return;
}
PomRead pomRead = new PomRead();
try {
String version = pomRead.getVersionFromPom(pomFile);
System.out.println(version);
} catch (IllegalArgumentException e) {
System.err.println(e.getMessage());
} catch (IOException e) {
System.err.println(e.getMessage());
} catch (XmlPullParserException e) {
System.err.println(e.getMessage());
}
}
}
You need of course the following pom.xml for that small program where a single dependency is important:
<dependency>
<groupId>org.apache.maven</groupId>
<artifactId>maven-model</artifactId>
<version>3.0.5</version>
</dependency>
May be it should be added such a goal to one of the numerous maven plugins to support such a thing. The above prints out the version only but can simply be enhanced to print also groupId and artifactId.