How to JSON parse immutable object in Java + Jersey

Question

So I am just trying out Jersey for REST services and it seems to we working out fine. I only expose get services and all of the object types that I expose with these services have an immutable object representation in Java. By default Jersey seems to use a parser (JAXB?), requiring a @XmlRootElement annotation for the class that should be parsed, zero-arg constructor and setters.

I have been using Gson with no zero-arg constructor, no setters and final on all fields with no problems at all. Is there any way to accomplish this with Jersey(ie the paser it is using)? I have seen solutions with adapter classes that map data from a immutable object to a mutable representation, but this seems like a lot of boilerplate(new classes, more annotations, etc.) if it can be achieved with Gson without anything added.

Note: 1) I have heard people promote using zero-arg constructor and claim that Gson should not work without it. This is not what I am interested in. 2) I really have tried googling this but my keywords might be off. In other words, humiliate me in moderation.

EDIT 1: My webservice works if I do like this:

@XmlRootElement
public class Code{
    private String code; //Silly object just used for example.
    public Code(){}
    //(G || S)etters
}

With this class exposing the object:

@GET
@Produces(MediaType.APPLICATION_JSON)
public Set<Code> get(@QueryParam("name") String name) { // Here I want to use a class of my own instead of String name, haven't figured out how yet.
    return this.codeService.get(name); 
}   

If I replace the Code with the following, the webservice stops working:

public class Code{
    private final String code;

    @JsonCreator
    public Code(@JsonProperty("code") String code) {
        this.code = code;
    }
    //Getters omitted
}

What I want is to be able to 1) have immutable objects that can be parsed to/from json and 2) Be able to define something like @RequestBody in Spring MVC for my incoming objects.

Answer 1

Actually this could be pretty easy with Genson . You just need the jar and then configure the Genson feature to use constructors with arguments (if you don't want to put annotations on it).

Genson genson = new GensonBuilder().useConstructorWithArguments(true).create();
// and then register it with jersey
new ResourceConfig().register(new GensonJaxRSFeature().use(genson));

Or you can use JsonProperty on the arguments. See the User Guide for more details.