17.2. Pluggable JAXBContexts with ContextResolvers

We do not recommend using this feature unless you are familiar with the principles involved.
By default, RESTEasy creates and caches JAXBContext instances per class type depending on the class you are marshaling or unmarshaling. If you do not want RESTEasy to create JAXBContexts, you can plug in your own by implementing an instance of javax.ws.rs.ext.ContextResolver. 
 public interface ContextResolver<T>
 {
T getContext(Class<?> type);
 }

 @Provider
 @Produces("application/xml")
 public class MyJAXBContextResolver implements ContextResolver<JAXBContext>
 {
JAXBContext getContext(Class<?> type)
{
   if (type.equals(WhateverClassIsOverridedFor.class)) return JAXBContext.newInstance()...;
}
 }
You must provide a @Produces annotation to specify the types of media intended for the context. You must also implement ContextResolver<JAXBContext>. This helps the runtime match the correct context resolver. You must also annotate the ContextResolver class with @Provider.
There are several ways to make this ContextResolver available.
  1. return it as a class or instance from a javax.ws.rs.core.Application implementation.
  2. list it as a provider with resteasy.providers.
  3. let RESTEasy automatically scan for it within your WAR file. (See the Configuration Guide for more details.)
  4. add it manually via ResteasyProviderFactory.getInstance().registerProvider(Class) or registerProviderInstance(Object).