apt - 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

While I have no problem with the use gradle makes of Ant, I agree with the original poster that it is undesirable in this case. I found a github project by Tom Anderson here that describes what I believe is a better approach. I modified it a small amount to fit my needs (output to src/main/generated) so that it looks like:

sourceSets {
     generated
}

sourceSets.generated.java.srcDirs = ['src/main/generated']

configurations {
     querydslapt
}

dependencies {     
    compile 'mine go here'
    querydslapt 'com.mysema.querydsl:querydsl-apt:2.7.1'
}

task generateQueryDSL(type: Compile, group: 'build', description: 'Generates the QueryDSL query types') {
         source = sourceSets.main.java
         classpath = configurations.compile + configurations.querydslapt
         options.compilerArgs = [
                "-proc:only",
                "-processor", "com.mysema.query.apt.jpa.JPAAnnotationProcessor"
         ]
         destinationDir = sourceSets.generated.java.srcDirs.iterator().next()
}
compileJava.dependsOn generateQueryDSL

This approach makes a lot more sense to me than the other, if it does to you too, then you have another option for querydsl generation.