change resource provider dynamically with CXF jaxrs server?

I am trying to set up unit tests with my resource provider deployed to CXF jaxrs server. The code example is like the following

        JAXRSServerFactoryBean sf = new JAXRSServerFactoryBean();
        sf.setResourceClasses(MyResource.class);

        List<Object> providers = new ArrayList<Object>();
        providers.add( new RuntimeExceptionMapper());

        sf.setProviders(providers);
        sf.setAddress(SERVER_URL);

        sf.setResourceProvider(MyResource.class,
                new SingletonResourceProvider(resourceInstance, true));
        server = sf.create();    

My question is I need to plug in different service mock to my resource provider for tests of different branches. Right now I am shutting down the server after each test method, recreate the resource provider with desired service mock and recreate the server. I am just wondering if I can grab the resource provider after the server is up, and change the service mock used there. Or there exists any other not as expensive operations to achieve what I have right now.

Hope I explain it well. Thank you for any helps/hints