Using Maven Ant Tasks

Declaring Dependencies

The main purpose of the Maven Ant Tasks is to utilize Maven's dependency management features.

This is achieved with the dependencies task. The simplest usage involves specifying your dependencies inline, such as in the following example:

<artifact:dependencies pathId="dependency.classpath">
  <dependency groupId="junit" artifactId="junit" version="3.8.2" scope="test"/>
  <dependency groupId="org.codehaus.modello" artifactId="modello-core" version="1.0-alpha-2-SNAPSHOT"/>
  <dependency groupId="javax.servlet" artifactId="servlet-api" version="2.4" scope="provided"/>
</artifact:dependencies>

The above example will download those 3 dependencies, and their dependencies, and so on. They will be stored in the default local repository location, ${user.home}/.m2/repository.

You may have noticed the pathId reference. This is optional, but if given will create a classpath reference that includes the local files downloaded as dependencies. This is usually used to pass to javac or other tasks:

You can also use a Maven 2.0 POM to declare your dependencies, which is described in the examples. This is the recommended practice so that you can reuse the file to deploy your own artifacts.

For more examples of using the dependencies task, see the examples page.

Installing and Deploying Your Own Artifacts to a Repository

Maven allows artifacts to be shared between projects by using local and remote repository. The install task allows an artifact to be copied to the local maven repository (typically located in ~/.m2/repository).

The deploy task allows artifacts to be deployed to a remote maven repository where they will be available to other projects.

For examples of using the install and deploy tasks, see the examples page.

Using a Maven POM File

In Maven, the Project Object Model (POM) represents a unit of work - one exists for each artifact that is built.

A Maven 2.0 POM file is required for deploying your own artifact to a repository for use in the dependencies elements of other projects.

It can also be reused for declaring your own dependencies, instead of specifying the inline version given earlier.

For examples of creating a pom and using the pom task, see the examples page.

Declaring Repositories

All of the tasks can optionally take one or more remote repositories to download from and upload to, and a local repository to store downloaded and installed archives to.

These can be specified inline, or if you choose to reuse them, they can be declared with an id/refid combination.

For example, you can specify the remote repository you want to use:

<artifact:remoteRepository id="remote.repository" url="http://repository.mycompany.com/" />
...
<artifact:dependencies>
  <!-- Your dependency definitions go here -->
  ...
  <remoteRepository refid="remote.repository" />
</artifact:dependencies>

If no remote repositories are specified, the default http://repo1.maven.org/maven2/ is used. But if at least one remote repository is specified, repo1 is not automatically added: you have to declare it if you need it.

Note: to work with transitive dependencies, you must use a Maven 2.0 repository.

If your repository requires authentication, you can provide this as a nested element. It accepts the attributes username, password, and for SSH based repositories privateKey and passphrase. For example:

<authentication username="brett" privateKey="${user.home}/.ssh/id_dsa" />

The Settings File

The POM can be used to represent most of the information that the tasks have access to, including remote repositories. Information that are user or environment specific, such as the authentication tag, are specified in the settings.xml file in Maven, and can also be accessed from the Ant tasks.

The file is first looked for in ${user.home}/.ant/settings.xml, then in ${user.home}/.m2/settings.xml so that the settings can be shared with Maven 2.0 itself. Since 2.0.7, it is then looked for in ${ANT_HOME}/etc/settings.xml, then in ${M2_HOME}/conf/settings.xml so that the settings can be set for all users.

Since 2.0.6, you can provide access to a settings file anywhere using settingsFile attribute:

<artifact:dependencies settingsFile="/opt/maven/conf/settings.xml">
  ...
</artifact:dependencies>

For example, to specify your proxy settings, you would specify the following settings.xml file:

<settings>
  <proxies>
    <proxy>
      <protocol>http</protocol>
      <host>proxy.host.net</host>
      <port>8080</port>
      <nonProxyHosts>localhost</nonProxyHosts>
    </proxy>
  </proxies>
</settings>

Or to specify a central mirror, you would specify the following settings.xml file:

<settings>
  <mirrors>
    <mirror>
      <id>central.mirror</id>
      <url>http://mirror.host.net/maven2</url>
      <mirrorOf>central</mirrorOf>
    </mirror>
  </mirrors>
</settings>

For more information on configuring settings.xml, see:

More Examples

  • Maven Ant Tasks's sample.build.xml is a sample Ant script showing most of the functionality in action (it's used as unit-tests).
  • Maven itself can be bootstrapped using Maven Ant Tasks: see build.xml in Maven Core sources. Note that most content is about building Maven project: there is only a little part that is using Maven Ant Tasks, to get dependencies, ie the pull target (with its depends targets).