How to map a http request parameter to an Enum in java?

Question

I’m making an ajax requisition like this:

$.ajax({
    type : 'POST',
    url : apiURL + '/play',
    dataType : "json",
    data : {
        against : "ANYBODY"
    },
    success : function(data, textStatus, jqXHR) {
        // ...
    },
    error : function(jqXHR, textStatus, errorThrown) {
        // ...
    },
});

And receiving (successfully) the data on the server like this:

@POST
@Path("play")
@Consumes(MediaType.APPLICATION_FORM_URLENCODED)
@Produces(MediaType.APPLICATION_JSON)
public Game play(@FormParam("against") String param) {
    Against against = Against.valueOf(param);
    switch(against) {
    case ANYBODY:
    // ...

Note that Against is a trivial Enum:

public enum Against {
    ANYBODY, ANY_FRIEND, A_FRIEND;
}

My doubt: is it possible to receive Enum directly, as in the example below? Do you know any changes in javascript and/or java code that allow me to do this?

@POST
@Path("play")
@Consumes(MediaType.APPLICATION_JSON)
@Produces(MediaType.APPLICATION_JSON)
public Game play(Against against) {
    switch(against) {
    case ANYBODY:
    // ...

Answer 1

According to the jersey documentation, the types used in the parameters annotated with @*Param (as @QueryParam and @FormParam) must not fit in one of the following items:

1. To be a primitive kind
2. Have a constructor that accepts a single argument String
3. Have a static method called valueOf or fromString accepting a single String parameter
4. Have a registered implementation of the JAX-RS SPI extension javax.ws.rs.ext.ParamConverterProvider which returns an instance of javax.ws.rs.ext.ParamConverter capable of converting a String to the desired type
5. Being a Collection like List<T>, Set<T> or SortedSet<T>, where T satisfy items 2 or 3 above.

As a Enum has the method valueOf, the same fits in item 2. Soon it would be perfectly possible to do:

public Game play(@FormParam("against") Against param) { 
    ...
}

---

Updating

There’s another solution I usually use with custom types, which is to write a MessageBodyReader to treat automatic deserialization of this type.

It may be possible to write a generic for enums, but I have never tried.