Best way to send java.lang.Class via dispatch?

Question

here's the setup: I'm using GWT 2.4 with gwt-platform 0.7. I have a bunch of classes that contain key-value-pairs (at the moment int->String). They are just different classes because they get saved to different tables in database via JPA.

Now I'd like to have one(!) method to fetch this data from the server.

I first tried to send to the server the classes I'd like to fetch using ArrayList<Class<?>>. And answer with HashMap<Class<?>, HashMap<Integer, String>>. But GWT doesn't allow to serialize Class<?>. This way I could get all the database entries and display them with the right class associated (that's important) very easily.

Now I am looking for another way to get it working without having to write lot's of code.

The first new idea was to have a HashMap<String, Class<?>> somewhere inside the shared folder and just transfer the String over the wire. So the client and server would have to create a new object by finding the class via the String in the HashMap.

Is there any other good solution for this?

Thank you.

Bradley Gottfried · Accepted Answer · 2012-06-15T13:17:48.670

public Enum ClassType {
  A, B, C
}

public class AType {
  HashMap<Integer, String> myHashMap;
  ClassType getClassType() {
      return ClassType.A;
  }
}

public interface TransferableHashMap extends IsSerializable {
   ClassType getClassType();
}

public interface transferService extends RemoteService {
    HashSet<TransferableHashMap> getMaps(HashSet<ClassType> request);
}


//somewhere on the client
final Set<AType> as = new Set<AType>();
final Set<BType> bs = new Set<BType>();
final Set<CType> cs = new Set<CType>();

Set<ClassType> request = new HashSet<ClassType>();
request.add(ClassType.A);
request.add(ClassType.B);
request.add(ClassType.C);

transferService.getMaps(request, 
  new AsyncCallback<HashSet<TransferableHashMap>>(){

  @Override
  public void onSuccess(HashSet<TransferableHashMap>> result) {
      for (TransferableHashMap entry : result) {
        if(entry instanceof Atype) as.add((AType)entry);
        else if(entry instanceof Btype) bs.add((BType)entry);
        else if(entry instanceof Ctype) cs.add((CType)entry);
        else throw new SerializationException();
        }
    }
  });

That's how I'd do it.

Best way to send java.lang.Class via dispatch?

1 Answers1