How to serialize Java primitives using Jersey REST

Question

In my application I use Jersey REST to serialize complex objects. This works quite fine. But there are a few method which simply return an int or boolean.

Jersey can't handle primitive types (to my knowledge), probably because they're no annotated and Jersey has no default annotation for them. I worked around that by creating complex types like a RestBoolean or RestInteger, which simply hold an int or boolean value and have the appropriate annotations.

Isn't there an easier way than writing these container objects?

Answer 1

Are you writing a service or a client? In the service-end of things, you would simply write a MessageBodyWriter to serialize a stream of data to a Java object for your types. In my use cases, the services I'm writing output to JSON or XML, and in XML's case, I just throw one JAXB annotation on the top of my classes and I'm done.

Have you looked at the Jersey User guide regarding this?

3.6. Adding support for new representations

Answer 2

Actually your best bet is to write a custom ContextResolver Provider like the following that uses natural building of JSON.

   @Provider
   public class YourContextResolver implements ContextResolver<JAXBContext> {

    private JAXBContext context;
    private Class<?>[] types = { YourSpecialBean.class };

    public YourContextResolver() throws Exception {
        this.context = new JSONJAXBContext(
                JSONConfiguration.natural().build(), types);
    }

    public JAXBContext getContext(Class<?> objectType) {
        for (int i = 0; i < this.types.length; i++)
            if (this.types[i].equals(objectType)) return context;

        return null;
    }
}

The only thing special here to notice is the YourSpecialBean.class in the Class[]. This defines an array of class types that this provider will resolve naturally.