Custom JSON marshalling with JAX-RS on Glassfish/Payara

Question

I am curious to know which JSON marshalling/unmarshalling framework is used by Glassfish/Payara is case of JAX-RS and how I can add custom JSON mapper class into it.

I would like to write a custom serializer for my Enum class. I use provided scope in my pom.xml for jaxrs javaee-api 7.0 so default Glassfish libraries are used.

I tried to use @JsonValue and wrote a class which implements javax.ws.rs.ext.MessageBodyWriter and JsonSerializer<T> as well. Do not work either as I expect.

This is my enum class:

public enum ErrorCode {
    MY_ERROR(123456);

    private int value;

    ErrorCode(final int value) {
        this.value = value;
    }

    @JsonValue
    public int  getValue() {
        return value;
    }
}

The class which uses enum:

public class ErrorInfo {
    private ErrorCode errorCode;

    public String toJson() {
        try {
            return new ObjectMapper().writer().withDefaultPrettyPrinter().writeValueAsString(this);
        } catch (JsonProcessingException e) {
            // TODO: do something here...
        }
    }
}

And the JAX-RS class where I would like to send back the ErrorInfo instance as a JSON:

@Provider
public class MyExceptionMapper implements ExceptionMapper<Throwable> {
    @Override
    public Response toResponse(Throwable throwable) {
        ...
        return Response
                .status(errorInfo.getHttpStatus())
                .type(ExtendedMediaType.APPLICATION_JSON_UTF8)
                .entity(errorInfo)
                .build();
    }
}

If I use the code above then the errorCode value is "MY_ERROR" string instead of the int 123456 value.

If I use my extra errorInfo.toJson() method then @JsonValue annotation does the magic but I would like to avoid writing extra code to handle enum serialization issue.

What is the proper way to configure / add extra enum mapper class to the default JAX-RS JSON library in Glassfish/Payara?

Answer 1

By default, Payara Server uses MOXy to map to/from JSON. You can use an alternative like Jackson, if you add Jackson to your app and add JacksonFeature into JAX-RS classes: Force Glassfish4 to use Jackson instead of Moxy

In the upcoming Payara 5, which will support Java EE 8, JSON marshalling will be handled in a standard way prescribed by the JSON-Binding