How to use the maven ant task from gradle?

I am trying to publish some artifacts to the maven central repo and since the current version of gradle (0.9-rc2) does not handle pgp I thought I would give it a try by 'porting' the ant xml version while waiting for gradle 1.0 which hopefully will support it out of the box.

I wrote the following in gradle:

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

  mvn.mvn {
    arg(value: 'org.apache.maven.plugins:maven-gpg-plugin:1.1:sign-and-deploy-file')
    arg(value: '-Durl=file:///tmp/repo2')
    arg(value: '-DrepositoryId=sonatype-nexus-staging')
    arg(value: '-DpomFile=pom.xml')
    arg(value: '-Dfile=myjar.jar')
    arg(value: '-Dfile=-Pgpg')
  }

Unfortunately it is not working and I am getting this:

Cause: Problem: failed to create task or type antlib:org.apache.maven.artifact.ant:mvn
Cause: The name is unde开发者_运维百科fined.
Action: Check the spelling.
Action: Check that any custom tasks/types have been declared.
Action: Check that any <presetdef>/<macrodef> declarations have taken place.
No types or tasks have been defined in this namespace yet

I have tried various combinations including adding the following at the top of my script:

buildscript {
  repositories {
    mavenCentral()
  }
  dependencies {
    classpath 'org.apache.maven:maven-ant-tasks:2.1.1'
  }
}

Any help would be much appreciated

Thanks Yan

---

I did not find a way to use NamespaceBuilder but I found another way to be able to use the task directly which solves my issue:

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)
  ant.mvn(...)
}