REST with Java (JAX-RS) using Jersey - jersey

Question

I developed a restful web service via Jersey in Java (JAX-RS) : http://www.vogella.com/articles/REST/article.html
Then I used the Hibernate Technology to map the data to the database.
Finally I developed an android application to display data.
This is an example of a method in my Web Service :
#GET
#Path("/project_id/username/get/{projectId}/{username}/")
#Consumes(MediaType.APPLICATION_JSON)
#Produces(MediaType.APPLICATION_JSON)
public Response deliverableList(#PathParam("projectId") long projectId,
#PathParam("username") String username) {
Session session = HibernateUtil.getSessionFactory().getCurrentSession();
session.beginTransaction();
List<Deliverable> list = null;
try {
list= (List<Deliverable>) session.createQuery(
"from Deliverable as d where d.project.id= :id").setLong("id", projectId).list();
} catch (HibernateException e) {
e.printStackTrace();
session.getTransaction().rollback();
}
session.getTransaction().commit();
return Response.status(201).entity(list).build();
}
as you see I used "Response.status(201).entity(list).build()" to transfer the list of data. Is it a good way? if not what is your suggestion to transfer the data. Please support your explanation with some codes and examples.

Answer 1

Response.ok().enity(object).build() is the correct way to return data
You really want to move your hibernate stuff to a data access tier... it's going to be hard to manage intermingled with your service tier
I completely disagree with smcg about using a helper method to map the java to json. Use the jax-rs annotations on your beans to do it unless you have really complicated requirements: see http://wiki.fasterxml.com/JacksonAnnotations

Answer 2

It seems to me like you are relying on something to automagically map your Java objects to JSON - probably Jackson. I do not personally prefer this method. Instead, I use Jettison and create my own mapping from Java to a Jettison JSONObject object. Then I use the JSONObject (or JSONArray) as the entity. My return statement would be something like this:
return Response.ok().entity(myObjectAsJSON).build();
In the case of returning a list of things, use a JSONArray instead of a JSONObject.
You'll want a helper method to map the Java object to JSON.
public JSONArray deliverableListToJSON(List<Deliverable> deliverables)
throws JSONException {
JSONArray result = new JSONArray();
for(Deliverable deliverable : deliverables) {
JSONObject deliverableJSON = new JSONObject();
deliverableJSON.put("importantValue", deliverable.getImportantValue());
result.put(deliverableJSON);
}
return result;
}
This approach gives you more flexibility and doesn't force you to have public getters and setters for all your fields.