Reading info from existing pom.xml file using Gradle?

Question

In Ant the Maven Ant Tasks can be used to read maven properties like this:

<artifact:pom id="mypom" file="pom.xml" />
<echo>The version is ${mypom.version}</echo>

Is there "native" support in Gradle for accessing pom elements from an existing physical pom.xml file or do I need to go through the above Ant approach in my .gradle file to make this work?

This page:

http://gradle.org/docs/current/userguide/maven_plugin.html

has info on generating pom files but thats not what I am looking for. I have tried to create a .gradle file that does the same:

    repositories {
      mavenCentral()
    }

    configurations {
        mavenAntTasks
    }

    dependencies {
        mavenAntTasks 'org.apache.maven:maven-ant-tasks:2.1.1'
    }

    task hello << {
      ant.taskdef(resource: 'org/apache/maven/artifact/ant/antlib.xml',
                  uri: 'antlib:org.apache.maven.artifact.ant',
                  classpath: configurations.mavenAntTasks.asPath)

     // what is the gradle syntax for this:
     // <artifact:pom id="mypom" file="maven-project/pom.xml" />
     // its not a property or a task...
     def artifact = groovy.xml.NamespaceBuilder.newInstance(ant,'antlib:org.apache.maven.artifact.ant')
     artifact.pom(id:'mypom', file: 'pom.xml')
     def text = properties['mypom.version']
     println "From pom file: " + text 

    }

where I have a simple pom.xml file located next to the build.gradle file. But I can't find any info in the gradle docs on the corresponding ant calls for this task. I have looked at:

http://www.gradle.org/docs/current/userguide/ant.html

for how to read ant properties and references but this:

<artifact:pom id="mypom" file="maven-project/pom.xml" />

seems to be neither a property or reference. I stumbled on this page:

http://snipplr.com/view/4082/

where a NamespaceBuilder is used:

 def mvn = groovy.xml.NamespaceBuilder.newInstance(ant, 'antlib:org.apache.maven.artifact.ant')

but when using this approach I get:

The AbstractTask.getDynamicObjectHelper() method has been deprecated and will be removed in the next version of Gradle. Please use the getAsDynamicObject() method instead.
From pom file: null

after a bit of googling I found:

http://issues.gradle.org/browse/GRADLE-2385

which seems related, but the value of the property is still null.

Answer 1

Gradle doesn't provide native support for parsing POM files, but Groovy's XmlSlurper makes XML parsing easy and convenient. I'd probably prefer that over the Ant approach.

Answer 2

The following code snip should work out.

defaultTasks 'hello'

repositories {
  mavenCentral()
}
configurations {
  mavenAntTasks
}
dependencies {
  mavenAntTasks 'org.apache.maven:maven-ant-tasks:2.1.3'
}

task hello << {
  ant.taskdef(
    resource: 'org/apache/maven/artifact/ant/antlib.xml',
    uri: 'antlib:org.apache.maven.artifact.ant',
    classpath: configurations.mavenAntTasks.asPath)

  ant.'antlib:org.apache.maven.artifact.ant:pom'(id:'mypom', file:'pom.xml')
  println ant.references['mypom'].version
}

Reading pom file by groovy xmlslurper is more forthright way, I think.