Procedure 12.8. Create a JAXB Decorator with RESTEasy

1. Create the Processor Class

   1. Create a class that implements DecoratorProcessor<Target, Annotation>. The target is either the JAXB Marshaller or Unmarshaller class. The annotation is created in step two.
   2. Annotate the class with @DecorateTypes, and declare the MIME Types the decorator should decorate.
   3. Set properties or values within the decorate function.

   Example 12.22. Example Processor Class

   import org.jboss.resteasy.core.interception.DecoratorProcessor;
   import org.jboss.resteasy.annotations.DecorateTypes;
   
   import javax.xml.bind.Marshaller;
   import javax.xml.bind.PropertyException;
   import javax.ws.rs.core.MediaType;
   import javax.ws.rs.Produces;
   import java.lang.annotation.Annotation;
   
   @DecorateTypes({"text/*+xml", "application/*+xml"})
   public class PrettyProcessor implements DecoratorProcessor<Marshaller, Pretty>
   {
       public Marshaller decorate(Marshaller target, Pretty annotation,
   	  Class type, Annotation[] annotations, MediaType mediaType)
       {
   	target.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
       }
   }
   
   

2. Create the Annotation

   1. Create a custom interface that is annotated with the @Decorator annotation.
   2. Declare the processor and target for the @Decorator annotation. The processor is created in step one. The target is either the JAXB Marshaller or Unmarshaller class.

   Example 12.23. Example Annotation

   import org.jboss.resteasy.annotations.Decorator;
   
   @Target({ElementType.TYPE, ElementType.METHOD, ElementType.PARAMETER, ElementType.FIELD})
   @Retention(RetentionPolicy.RUNTIME)
   @Decorator(processor = PrettyProcessor.class, target = Marshaller.class)
   public @interface Pretty {}
   
   

3. Add the annotation created in step two to a function so that either the input or output is decorated when it is marshalled.