Generating JPA2 Metamodel from a Gradle build script

Question

I'm trying to set up a Gradle build script for a new project. That project will use JPA 2 along with Querydsl.

On the following page of Querydsl's reference documentation, they explain how to set up their JPAAnnotationProcessor (apt) for Maven and Ant.

I would like to do the same with Gradle, but I don't know how and my beloved friend did not help me much on this one. I need to find a way to invoke Javac (preferably without any additional dependencies) with arguments to be able to specify the processor that apt should use (?)

Answer 1

I did not test it but this should work:

repositories {
    mavenCentral()
}
apply plugin: 'java'
dependencies {
   compile(group: 'com.mysema.querydsl', name: 'querydsl-apt', version: '1.8.4')
   compile(group: 'com.mysema.querydsl', name: 'querydsl-jpa', version: '1.8.4')
   compile(group: 'org.slf4j', name: 'slf4j-log4j12', version: '1.6.1')
}

compileJava {
    doFirst {
        Map otherArgs = [
            includeAntRuntime: false,
            destdir: destinationDir,
            classpath: configurations.compile.asPath,
            sourcepath: '',
            target: targetCompatibility,
            source: sourceCompatibility
        ]
        options.compilerArgs = [
            '-processor', 'com.mysema.query.apt.jpa.JPAAnnotationProcessor',
            '-s', "${destinationDir.absolutePath}".toString()
        ]
        Map antOptions = otherArgs + options.optionMap()
        ant.javac(antOptions) {
            source.addToAntBuilder(ant, 'src', FileCollection.AntType.MatchingTask)
            options.compilerArgs.each {value ->
                compilerarg(value: value)
            }
        }
    }
}

Hope it helps.