Can I use the path to a Maven dependency as a property? - maven-2

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

Here is a correct implementation, using the maven-dependency-plugin properties goal, which can be used anywhere in a pom:
<?xml version="1.0" encoding="UTF-8"?>
<project>
<modelVersion>4.0.0</modelVersion>
<groupId>com.stackoverflow</groupId>
<artifactId>q2359872</artifactId>
<version>2.0-SNAPSHOT</version>
<name>q2359872</name>
<properties>
<!-- Must be listed in the dependencies section otherwise it will be null. -->
<my.lib>${org.jmockit:jmockit:jar}</my.lib>
</properties>
<dependencies>
<dependency>
<groupId>org.jmockit</groupId>
<artifactId>jmockit</artifactId>
<version>1.11</version>
</dependency>
</dependencies>
<build>
<defaultGoal>generate-sources</defaultGoal>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<version>2.3</version>
<executions>
<execution>
<goals>
<goal>properties</goal>
</goals>
</execution>
</executions>
</plugin>
<!-- Example usage: -->
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>exec-maven-plugin</artifactId>
<version>1.2</version>
<executions>
<execution>
<goals>
<goal>exec</goal>
</goals>
<phase>generate-sources</phase>
</execution>
</executions>
<configuration>
<executable>echo</executable>
<arguments>
<argument>path to jar=</argument>
<argument>${org.jmockit:jmockit:jar}</argument>
<argument>my.lib=</argument>
<argument>${my.lib}</argument>
</arguments>
</configuration>
</plugin>
<!-- end of Example usage -->
</plugins>
</build>
</project>
And the output is...
jpyeron#black /projects/wkspc/tmp/foo
$ /cygdrive/c/programs.x86_64/apache-software-foundation/apache-maven-3.1.1/bin/mvn
[INFO] Scanning for projects...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building q2359872 2.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] --- maven-dependency-plugin:2.3:properties (default) # q2359872 ---
[INFO]
[INFO] --- exec-maven-plugin:1.2:exec (default) # q2359872 ---
path to jar= C:\Documents and Settings\jpyeron\.m2\repository\org\jmockit\jmockit\1.11\jmockit-1.11.jar my.lib= C:\Documents and Settings\jpyeron\.m2\repository\org\jmockit\jmockit\1.11\jmockit-1.11.jar
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 2.032s
[INFO] Finished at: Wed Sep 17 12:07:18 EDT 2014
[INFO] Final Memory: 10M/153M
[INFO] ------------------------------------------------------------------------

Answer 2

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 3

There is a plugin which might be what you are looking for... bitstrings.org (home).

Answer 4

If none of the upper work, you can always use gmaven to agressively dive into MavenProject object and get your artifact infos. In my case, I had the following artifact declared in a profile :
<!-- Neo4J connector. This dependency is scoped to be usable by maven-exec-plugin
which installs it in Glassfish -->
<dependency>
<groupId>com.netoprise</groupId>
<artifactId>neo4j-connector</artifactId>
<version>${neo4j.connector.version}</version>
<type>rar</type>
<!-- Set in test scope to avoid release issues -->
<scope>test</scope>
</dependency>
To get its path and put it in a maven property, I wrote the following gmaven script :
<!-- Small script used to build maven property for neo4j-connector path -->
<plugin>
<groupId>org.codehaus.gmaven</groupId>
<artifactId>gmaven-plugin</artifactId>
<version>1.3</version>
<executions>
<execution>
<id>get-neo4j-connector-rar-path</id>
<phase>validate</phase>
<goals>
<goal>execute</goal>
</goals>
<configuration>
<source>
<![CDATA[
println "initial value of neo4j.connector.rarPath is \""+project.properties['neo4j.connector.rarPath']+"\""
// Duplicate model in a Mavenproject, allowing me to get associated artifact
// So sad I can't get the embdder object
// More info here : http://maven.apache.org/ref/3.0.3/maven-core/apidocs/org/apache/maven/project/MavenProject.html
def mavenProject = new org.apache.maven.project.MavenProject(project)
// More infos on Artifact there : http://maven.apache.org/ref/3.0.3/maven-artifact/apidocs/org/apache/maven/artifact/Artifact.html
def neo4jConnector = mavenProject.getArtifacts().find { artifact -> artifact.getArtifactId()=='neo4j-connector' }
// Now resolve dependency to produce an artifact
// notice maven property interpolation doesn't do toString, so we have to do it ourselves
project.properties['neo4j.connector.rarPath'] = neo4jConnector.getFile().getAbsolutePath()
println "usable neoj4Connector can be found at "+project.properties['neo4j.connector.rarPath']
]]>
</source>
</configuration>
</execution>
</executions>
</plugin>
It's some kind of brute-force method, but it DO work far better than the previous solutions I've seen there.

Answer 5

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.