Section A.2. Auto-Downloading a Plug-in

A.2. Auto-Downloading a Plug-in

Maven has a Plugin plug-in that allows you to download and install plug-ins from one or several Maven remote repositories. To use it, type the following on a single line:

maven plugin:download    -DgroupId=[plug-in group id]   -DartifactId=[plug-in artifact id]   -Dversion=[plug-in version]

where:

• [plug-in group id] is the plug-in's groupId. For all plug-ins provided by Maven, that's maven.

• [plug-in artifact id] is the plug-in's artifactId. For example, for the JAR plug-in that's maven-jar-plugin.

• [plugin-in version] is the version of the plug-in you wish to download.

The best way to get these values is to know the URL where the plug-in JAR is located and to deduce these values from the URL. Figure A-1 shows an example of the URL for the JAR plug-in version 1.7 located on ibiblio. The values of artifactId, groupId, and version can easily be deduced.

Figure A-1. Mapping between plug-in URL and groupId, artifactId, and version for the Jar plug-in v1.7

If you don't specify the Maven remote repository to use, Maven will use ibiblio by default. You can change it by defining the maven.repo.remote property (either on the command line or in your properties files). This property defines the list of remote repositories to use. For example, to specify both ibiblio and maven-plugins.sf you would write:

maven.repo.remote = http://www.ibiblio.org,http://maven-plugins.sf.net/maven

Note that this is probably not necessary, as the maven-plguins.sf repository is synced with the ibiblio one every few hours.

Please note that Section 2.1 also explains how to install a new plug-in using this strategy.