@RequestHeader Map map default case?

Question

In spring 3.2, we make use of this in our controllers:

@RequestHeader Map<String, String> headers

The issue is that the map of header keys can be any case, so we have to re-build the header map, forcing the keys to lowercase.

It would be nice if spring would consistently force lowercase or uppercase on the headers in the map in order to make it easier for header checking.

Looking into how to alter that behavior is difficult, same goes for the spring mvc test setups.

We could override the RequestHeaderMapMethodArgumentResolver but how?

Answer 1

Yes, you can override RequestHeaderMapMethodArgumentResolver. Here's one way of doing it:

import org.apache.commons.collections.map.CaseInsensitiveMap;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.core.MethodParameter;
import org.springframework.web.bind.support.WebDataBinderFactory;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.method.annotation.RequestHeaderMapMethodArgumentResolver;
import org.springframework.web.method.support.ModelAndViewContainer;

import java.util.Map;

public class FixRequestHeaderMapMethodArgumentResolverConfigurer implements BeanPostProcessor {
    @Override
    public Object postProcessBeforeInitialization(Object bean, String s) throws BeansException {
        return bean;
    }

    @Override
    public Object postProcessAfterInitialization(Object bean, String s) throws BeansException {
        if(bean instanceof RequestHeaderMapMethodArgumentResolver) {
            return new RequestHeaderMapMethodArgumentResolver() {
                @Override
                public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer, NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {
                    return new CaseInsensitiveMap((Map)super.resolveArgument(parameter, mavContainer, webRequest, binderFactory));
                }
            };
        } else
            return bean;
    }
}