@Produces/provider media type matching

Question

I am experimenting with api verioning and have a very peculiar requirement to work against. We are going to use content-negotiation i.e @Produces annotation for this and I w

Answer 1

You probabily should have to use a custom response mapper.

1.- Create a class implementing MessageBodyWriter in charge of writing the response

@Provider
public class MyResponseTypeMapper 
  implements MessageBodyWriter<MyResponseObjectType> {
     @Override
     public boolean isWriteable(final Class<?> type,final Type genericType,
                final Annotation[] annotations,
                final MediaType mediaType) {
       ... use one of the arguments (either the type, an annotation or the MediaType)
           to guess if the object shoud be written with this class
     }
     @Override
     public long getSize(final MyResponseObjectType myObjectTypeInstance,
                     final Class<?> type,final Type genericType,
                         final Annotation[] annotations,
                     final MediaType mediaType) {
        // return the exact response length if you know it... -1 otherwise
        return -1;
    }
    @Override
    public void writeTo(final MyResponseObjectType myObjectTypeInstance,
                    final Class<?> type,final Type genericType,
                    final Annotation[] annotations, 
                    final MediaType mediaType,
                    final MultivaluedMap<String,Object> httpHeaders,
                    final OutputStream entityStream) throws IOException,                                                                 WebApplicationException {
        ... serialize / marshall the MyResponseObjectType instance using
            whatever you like (jaxb, etC)
        entityStream.write(serializedObj.getBytes());
    }
}

2.- Register the Mappers in your app

public class MyRESTApp 
     extends Application  {
    @Override
public Set<Class<?>> getClasses() {
        Set<Class<?>> s = new HashSet<Class<?>>();
        s.add(MyResponseTypeMapper.class);
        return s;
    }
}

Jersey will scan all registered Mappers calling their isWriteable() method until one returns true... if so, this MessageBodyWriter instance will be used to serialize the content to the client