Get mapper from AuthenticationSuccessHandler - spring-security

Question

I'm trying to return some User data after a successful login in a Spring Boot application.
To do so, I need to serialize my Principal with the Jackson mapper that is already set-up at bootstrap via a factory.
Is there a way to inject it into the authentication handler?
#Override
public void onAuthenticationSuccess(HttpServletRequest request, HttpServletResponse response, Authentication authentication) throws IOException, ServletException {
response.setStatus(HttpServletResponse.SC_OK);
UserDetails me = (UserDetails) authentication.getPrincipal();
PrintWriter writer = response.getWriter();
/*mapper.writeValue(writer, user); <- how to get the mapper?
writer.flush();*/
}

Answer 1

tl;dr;
Instead of using a Factory, make the ObjectMapper a Spring bean. That way it can be injected into both Spring and Jersey components.
#Bean
public ObjectMapper mapper() {
ObjectMapper mapper = new ObjectMapper();
return mapper;
}
When you use an HK2 (Jersey's DI framework) Factory to create the ObjectMapper, the injection is only available to components that are retrieved through the HK2 ServiceLocator, which is the HK2 analogue of the Spring ApplicationContext.
When you use Spring-Boot with Jersey, how the two interact under the hood, is through the HK2 spring-bridge. So for example, say the AuthenticationSuccessHandler is registered in the ApplicationContext. With the spring-bridge configured, we can also get the AuthenticationSuccessHandler through the ServiceLocator
ServiceLocator l = ...
AuthenticationSuccessHandler handler = l.getService(AuthenticationSuccessHandler.class);
That should work. If you have the ObjectMapper binded through an HK2 Factory, and you were to #Inject the mapper into the AuthenticationSuccessHandler, it would be injected, when retrieved through the ServiceLocator.
That being said, Spring Security doesn't go through HK2, so it never has a chance to get the ObjectMapper through HK2. But if you register the mapper as a Spring bean, then Spring can inject it into the AuthenticationSuccessHandler. And the mapper is still available through HK2 ServiceLocator (because of the spring-bridge), so you can still use it with Jersey, same way as if it were binded with a Factory.