META-INF/services in JAR with Gradle

Question

I wanted to build a plugin module that can be loaded with a ServiceLoader. This requires adding a file to the META-INF/services directory, that is named after t

Answer 1

Meanwhile I found a solution to my problem in a (somewhat) similar Question.

Adding the following to the gradle.build file, resolves my problem

jar {
  from ('./src/main/java') {
    include 'META-INF/services/org.example.plugins.PluginService'
  }
}

Now the JAR file looks as expected

.
|- org
|  `- example
|     `- plugins
|        `- impl
|           `- ExamplePlugin.class
`- META-INF
   |- MANIFEST.MF
   `- services
      `- org.example.plugins.PluginService

Answer 2

Hopefully they will implement this in the jar task just like ant does. Somebody already worked on it: http://fgaliegue.blogspot.fr/2013/06/gradle-serviceloader-support.html

Answer 3

Hi Can try this: https://plugins.gradle.org/plugin/com.github.harbby.gradle.serviceloader

Usage

serviceLoader {
    serviceInterface 'org.example.plugins.PluginService'
    serviceInterface 'org.example.plugins.PluginService2'
}

Answer 4

You place META-INF/services/org.example.plugins.PluginService in src/main/java, but it's not a source, it's a resource file, therefore it should be placed in resources folder according to Maven directory layout convention, that is

src/main/resources/META-INF/services/org.example.plugins.PluginService

In this case everything should work out of the box.

Answer 5

If you happen to inherit some ant based legacy code that does not follow the maven conventions, the following may help.

Define your source sets to match the legacy structure, and include a line like this:

include 'META-INF/services/**'

In your source sets. This pattern is generic and will pick up all your meta inf services.

Full example below.

sourceSets {
    main {
        java {
            srcDir 'src'
            exclude '**/Test*.java'
        }
        resources {
            srcDir 'src'
            include '**/*.xml'
            include 'META-INF/services/**'
        }
    }
    test {
        java {
            srcDir 'src'
            include '**/Test*.java'

        }
        resources { srcDir 'resources' }
    }
}