Spring MVC and ICU ULocale

[ttmrb]

I am working on adding a Spring MVC module to an existing application. This application uses the ICU library for its internationalization, in particular the ULocale object. I am aware that the Spring MVC library automatically links each request with a java.util.Locale object so that it can be included in a Controller method as an argument. I would like to do the same thing with the ICU ULocale object. Does anyone have any advice on how best to accomplish this?

Here is an example of what I would like to be able to do:

@RequestMapping("/helloWorld")
public ModelAndView exampleControllerMethod(@RequestParam("id") param, ULocale icuLocale) {
    //...
}

The simplest solution I can think of is to write a simple converter that takes the java.util.Locale object that the Spring MVC LocaleResolver creates and pass it into an ICU ULocale object (The ULocale constructor takes a java.util.Locale). If I do this, does anyone know what converter I should use/interface I should implement?

Another possibility is to figure out how to make a similar LocaleResolver structure for the ULocale object. Advice on how to do that would be greatly appreciated. Thanks for your help.

[ttmrb]

Any help would be greatly appreciated. Thanks.

[ttmrb]

I finally managed to figure out how to accomplish my goal above. I am posting the answer for those who may stumble upon this in the future.

In Spring 3.1 there is a new interface called HandlerMethodArgumentResolver. It allows for the translation of web requests into the correct method argument. I created a new implementation of this interface called ULocaleMethodArgumentResolver which translates the java.util.Locale that the standard Spring MVC LocalResolver creates into a ICU ULocale object. Here is the code:

public class ULocaleMethodArgumentResolver implements HandlerMethodArgumentResolver {
    @Override
    public boolean supportsParameter(MethodParameter methodParameter) {
        return methodParameter.getParameterType().equals(ULocale.class);
    }

    @Override
    public Object resolveArgument(MethodParameter methodParameter, 
                                  ModelAndViewContainer modelAndViewContainer, 
                                  NativeWebRequest nativeWebRequest, 
                                  WebDataBinderFactory webDataBinderFactory) throws Exception {
        return ULocale.forLocale(nativeWebRequest.getLocale());
    }
}

Then in your Spring MVC context file, you add the bean to the argument-resolvers element in the annotation-driven element:

<mvc:annotation-driven>
    <mvc:argument-resolvers>
        <bean class="com.example.app.ULocaleMethodArgumentResolver"/>
    </mvc:argument-resolvers>
</mvc:annotation-driven>

For those using an older version of Spring, I found the WebArgumentResolver interface. I am not sure how it works but it looks similar.