Can I use the path to a Maven dependency as a property?

Question

I have a maven dependency in my pom.xml as such:

<dependency>
    <groupId>com.foo</groupId>
    <artifactId>Bar</artifactId>
    <version>1.2.3</version>
</dependency>

And I would like to use the system path to the binary as a property (so I can pass it to an external process that is kicked off by maven). I can do this in an awkward way:

<properties>
    <my.lib>${settings.localRepository}/com/foo/Bar/1.2.3/Bar.jar</my.lib>
</properties>

But I would really like to use a more standard mechanism, such as:

<properties>
    <my.lib>${com.foo:Bar:1.2.3}</my.lib>
</properties>

I something like that possible?

Answer 1

Assuming that the com.foo:Bar:jar:1.2.3 artifact is declared as dependency in your POM, the following property returns the path to the jar in the local repository:

${maven.dependency.com.foo.Bar.jar.path}

Update: Here is a simple POM demonstrating this:

<?xml version="1.0" encoding="UTF-8"?>
<project>
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.stackoverflow</groupId>
  <artifactId>q2359872</artifactId>
  <version>1.0-SNAPSHOT</version>
  <name>q2359872</name>
  <properties>
    <my.lib>${maven.dependency.junit.junit.jar.path}</my.lib>
  </properties>
  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
  </dependencies>
  <build>
    <plugins>
      <plugin>
        <artifactId>maven-antrun-plugin</artifactId>
        <executions>
          <execution>
            <phase>process-resources</phase>
            <configuration>
              <tasks>
                <echo>${my.lib}</echo>
              </tasks>
            </configuration>
            <goals>
              <goal>run</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
</project>

Running mvn process-resources produces the following output:

$ mvn process-resources
[INFO] Scanning for projects...
[INFO] ------------------------------------------------------------------------
[INFO] Building q2359872
[INFO]    task-segment: [process-resources]
[INFO] ------------------------------------------------------------------------
[INFO] [resources:resources {execution: default-resources}]
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory /home/pascal/Projects/stackoverflow/q2359872/src/main/resources
[INFO] [antrun:run {execution: default}]
[INFO] Executing tasks
     [echo] /home/pascal/.m2/repository/junit/junit/3.8.1/junit-3.8.1.jar
[INFO] Executed tasks
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESSFUL
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 7 seconds
[INFO] Finished at: Tue Mar 02 14:41:32 CET 2010
[INFO] Final Memory: 7M/68M
[INFO] ------------------------------------------------------------------------

Answer 2

You need to write a new maven plugin that sets a property value to the fully-resolved pathname of a dependency. The maven-dependency-plugin won't do that for you.

It will copy your dependency somewhere and then you can refer to it by that pathname.