Spring 3下如何实现DCI, Domain Events?

@Controller
@RequestMapping(value = "/contact")
public class UserController {

        //关键需要声明一个ServletContext 供WebAppUtil使用
	@Autowired   
	ServletContext context;

	@Autowired
	private SimpleJdbc simpleJdbc;

	@RequestMapping(method = RequestMethod.GET)
	public String list(Model model) {
		model.addAttribute("contacts", simpleJdbc.getUsers());
		return "contact/listContacts";
	}

	@RequestMapping(value = "/new", method = RequestMethod.GET)
	public String newForm() {
		return "contact/createContact";
	}

	@RequestMapping(value = "/new", method = RequestMethod.POST)
	public String newFormSave(@Valid UserModel user, BindingResult result) {
		if (result.hasErrors()) {
			return "contact/createContact";
		}
		user.setUserId(Integer.toString(user.hashCode()));
               //从Jdon框架中获得DCI的角色分配器
		RoleAssigner roleAssigner = (RoleAssigner) WebAppUtil.getComponentInstance("roleAssigner", context);
		RepositoryManagerIF rm = (RepositoryManagerIF) roleAssigner.assign(user, new RepositoryManagerEventImp());
		rm.remember(user);
		return ("contact/contactCreated");
	}
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