AnnotationMethodHandlerAdapter gives priority to media type order over quality when selecting a method [SPR-7000]

[spring-projects-issues]

Mike Youngstrom opened SPR-7000 and commented

AnnotationMethodHandlerAdapter.RequestMappingInfoComparator doesn't appear to order the requested accept value by quality. Meaning that if I submit a request value like the following:

(Taken from Webkit's standard accept header)

application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5

And I have a controller like the following:

@Controller
public class ExampleController {
    @RequestMapping(value="/secure/example", headers="accept=text/html", method=RequestMethod.GET)
    public String showHtml() {
        ...
    }

    @RequestMapping(value="/secure/example", headers="accept=image/png", method=RequestMethod.GET)
    public String showPng() {
        ...
    }
}

Then the showHtml method is selected because it is closest to the left where the showPng method should have been selected as it expresses a higher preferred quality level from the client (default quality=1).

This issue is related to #11663 but the order of the header media types should probably be taken into account AFTER the quality is taken into account.

This issue is also related to #11617 though since it appears #11617 won't make it into 3.0.x I think that this issue represents a more direct problem with a more straight forward solution that I believe should be included in to a 3.0.x release.

I think the order of media type method resolution should be the following:

1. Quality
2. Specificity
3. Order of content types from left to right (Provide mechanism for injecting a Serializable Provider<T> or ObjectFactory<T> via XML [SPR-6998] #11663)

FYI, the patch for #11617 includes a MediaType comparator that will sort by quality before specificity if you want to use it.

---

Affects: 3.0.1

Issue Links:

• MediaType Quality not being factored into mvc Content Negotiation [SPR-6952] #11617 MediaType Quality not being factored into mvc Content Negotiation

Referenced from: commits 753a540

[spring-projects-issues]

Arjen Poutsma commented

Fixed. Thanks for spotting this and providing us with a patch!