Grails: add a build task for compilation - grails

Question

I'm using grails 2.4.4.
Some of my classes are annotated and a APT (annotation processing tool) has to process these annotations during compilation to generate some sources.
I was able to get everything done with the workaround of creating a maven pom.xml by running grails generate-pom and from there add specific plugins and configure them.
Is there a possibility to use the built-in grails compiler config BuildConfig.groovy to reach the same goal without the detour via maven pom.xml?
To be more specific, I'm creating a workflow with AWS SWF. And SWF uses annotations that should generate some client classes. Therefor in the pom.xml I added this. It works perfectly when I run mvn compile:
<build>
...
<plugin>
<groupId>com.mysema.maven</groupId>
<artifactId>apt-maven-plugin</artifactId>
<version>1.1.3</version>
<executions>
<execution>
<goals>
<goal>process</goal>
</goals>
<configuration>
<outputDirectory>src/generated</outputDirectory>
<processor>com.amazonaws.eclipse.simpleworkflow.asynchrony.annotationprocessor.AsynchronyDeciderAnnotationProcessor</processor>
</configuration>
</execution>
</executions>
<dependencies>
<dependency>
<groupId>com.amazonaws</groupId>
<artifactId>aws-java-sdk-flow-build-tools</artifactId>
<version>1.9.34</version>
</dependency>
<dependency>
<groupId>org.freemarker</groupId>
<artifactId>freemarker</artifactId>
<version>2.3.21</version>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>3.3.2</version>
</dependency>
</dependencies>
</plugin>
...
</build>

Answer 1

I found out my self how to to it within grails.
Basically I created a script that you can call with the grails command. This script is nothing else but a gant script with which you can interfere with ant. Plus I had to add libraries to the libs folder in grails in order to have them in the classpath.
These are the steps:
Create a new grails script
grails create-script generateSources This will create a script called GenerateSources.groovy into your grails scripts directory
Edit the GenerateSources.groovy file
includeTargets << grailsScript("_GrailsCompile")
target(generateSources: "Generates sources for SWF workflow") {
ant.delete(dir:"src/generated/java")
ant.delete(dir:"target/generated-classes")
depends(compile)
ant.mkdir(dir:"src/generated/java")
ant.mkdir(dir:"target/generated-classes")
ant.javac(destdir:"target/generated-classes", classpathref:"grails.compile.classpath", source:"1.7", target:"1.7"){
compilerarg(value:"-proc:only")
compilerarg(value:"-s")
compilerarg(value:"src/generated/java")
src(path:"src/java")
}
}
setDefaultTarget(generateSources)
This includes references and tasks from the GrailsCompile script, deletes some folders (in case you re-run this script), calls the compile task from the native grails gant, creates the necessary target folders
Copy the necessary jars to the grails lib folder. In my case I had to copy the aws-java-sdk-flow-build-tools-1.9.34.jar which includes the Annotation processor and another dependence freemarker-2.3.18.jar. Javac will automatically call the correct APT in order to process the annotations in the the folder src/java
Run the script
grails generateSources which will run the compile task and your new task
Open:
I'd like to hook up this task automatically when grails compile is called. I'm still working on that thoug.