com.diffplug.gradle.p2

Class AsMavenPlugin

java.lang.Object

com.diffplug.gradle.ProjectPlugin

com.diffplug.gradle.p2.AsMavenPlugin

All Implemented Interfaces:

Plugin<Project>

public class AsMavenPlugin
extends ProjectPlugin

Downloads a set of artifacts from a p2 repository and stuffs them into a local maven repository in the build/p2asmaven folder, then adds this repository to the project.

apply plugin: 'com.diffplug.gradle.p2.asmaven'
p2AsMaven {
    // the maven group they shall have
    group 'eclipse-deps', {
        // the repositories and artifacts to download
        repoEclipse '4.5.2'
        iu          'org.eclipse.jdt.core'
    }
}

dependencies {
    compile 'eclipse-deps:org.eclipse.jdt.core:+'
}

You can also specify multiple groups, as such

def SUPPORTED_VERSIONS = ['4.4', '4.5', '4.6']
p2AsMaven {
    for (version in SUPPORTED_VERSIONS) {
        group 'eclipse-deps-' + version, {
            repoEclipse version
            iu 'org.eclipse.swt'
            // this will cause any OSGi jars which ask to be expanded into
            // folders to be exploded, e.g. Eclipse-BundleShape: dir 
            repo2runnable()
        }
    }
}

// build folder will look like this:
build/p2AsMaven/
    maven/
        eclipse-deps-4.4/
        eclipse-deps-4.5/
        eclipse-deps-4.6/
    p2/
        eclipse-deps-4.4/
        eclipse-deps-4.5/
        eclipse-deps-4.6/
    p2runnable/
        eclipse-deps-4.4/
        eclipse-deps-4.5/
        eclipse-deps-4.6/

The maven repository does not contain any dependency information, just the raw jars. In the example above, when p2 downloads org.eclipse.jdt.core, it also downloads all of its dependencies. But none of these dependencies are added automatically - you have to add them yourself.

See spotless for a production example.

Acknowledgements and comparisons to other options

Inspired by Andrey Hihlovskiy’s unpuzzle. Unpuzzle downloads a zipped-up copy of the eclipse IDE and stuffs its jars into a maven repository. Additionally, it parses out the Require-Bundle directives to put partial dependency information in the maven metadata.

Simon Templer has a fork which supports parsing the Import-Package and Export-Package directive to build even more detailed dependency information.

A third option is Dr. David Akehurst’s p2 dependency resolver, which is a partial re-implementation of P2, and uses internal gradle APIs to hook into Gradle’s dependency resolution. It’s very impressive, but it has a few limitations:

• It does not support composite repositories
• It does not work on Gradle > 2.8

All of the above are great work, and served as useful examples. The central problem which is the cause of so many not-quite-satisfying implementations is this:

• Using the real p2 is cumbersome, but possible.
• Re-implementing the first 70% of p2 is easy, but the last 30% is hard and moving (they’re still adding features).
• Gradle doesn’t yet have an extensible API for repositories.

In Goomph, we will always use the real p2. While we work around limitations in gradle and p2, we will only use public APIs in both products.

Constructor Summary

Constructors

Constructor and Description
AsMavenPlugin()

Method Summary

Modifier and Type	Method and Description
protected void	applyOnce(Project project) Plugin application, which is guaranteed to execute only once.
AsMavenExtension	extension()

Methods inherited from class com.diffplug.gradle.ProjectPlugin

apply, getPlugin, treeDef

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

AsMavenPlugin

public AsMavenPlugin()

Method Detail

applyOnce

protected void applyOnce(Project project)

Description copied from class: ProjectPlugin

Plugin application, which is guaranteed to execute only once.

Specified by:

applyOnce in class ProjectPlugin

extension

public AsMavenExtension extension()