how can i access controller method value in postHandle in spring mvc 's interceptor - spring-mvc

Question

#Override
public void postHandle(HttpServletRequest request,
HttpServletResponse response, Object handler,
ModelAndView modelAndView) throws Exception {
}
#Controller
public ModeAndView createUser(User user){
}
how can get controller method createUser's parameter user value
in interceptor 's postHandle ???

Answer 1

You cannot directly.
As you see in its parameters, an Interceptor has direct access to the request, the response and the ModelAndView. If you need to have access to the method parameter user, the simplest is to put it in model.
public ModeAndView createUser(User user){
ModelAndView mav = new ModelAndView();
mav.addAttribute("user", user);
...
return mav;
}
Then in interceptor postHandle method, you simply do
User user = (User) modelAndView.getAttribute("user");

Answer 2

You could write an org.springframework.web.servlet.HandlerInterceptor. (or its convenience subclass HandlerInterceptorAdapter)
#See: Spring Reference chapter: 15.4.1 Intercepting requests - the HandlerInterceptor interface
It has the method:
void postHandle(HttpServletRequest request,
HttpServletResponse response,
Object handler,
ModelAndView modelAndView) throws Exception;
This method is invoked after the controller is done and before the view is rendered. So you can use it, to add some properties to the ModelMap
An example:
public class VersionAddingHandlerInterceptor extends HandlerInterceptorAdapter {
/**
* The name under which the version is added to the model map.
*/
public static final String VERSION_MODEL_ATTRIBUTE_NAME =
"VersionAddingHandlerInterceptor_version";
/**
* it is my personal implmentation
* I wanted to demonstrate something usefull
*/
private VersionService versionService;
public VersionAddingHandlerInterceptor(final VersionService versionService) {
this.versionService = versionService;
}
#Override
public void postHandle(final HttpServletRequest request,
final HttpServletResponse response, final Object handler,
final ModelAndView modelAndView) throws Exception {
if (modelAndView != null) {
modelAndView.getModelMap().
addAttribute(VERSION_MODEL_ATTRIBUTE_NAME,
versionService.getVersion());
}
}
}
webmvc-config.xml
<mvc:interceptors>
<bean class="demo.VersionAddingHandlerInterceptor" autowire="constructor" />
</mvc:interceptors>