如何在Spring Boot中指定回退请求映射

Question

We have an endpoint which can return different responses depending on the Accept header. In particular, it can return zip files, video files, or audio files.

Mapping 1:

@RequestMapping(value = "endpoint",
        method = RequestMethod.GET,
        produces = {"video/*", "audio/*"})

Mappping 2:

@RequestMapping(value = "endpoint",
        method = RequestMethod.GET, produces = {"application/zip", "*/*"})

This setup will take an Accept: video/* and go to mapping 1 (which is what we want). But, Accept: video/mp4 results in an java.lang.IllegalStateException: Ambiguous handler methods mapped for HTTP path exception.

I would have expected that video/mp4 more closely matches mapping 1 and loads that. Indeed that is exactly what we do want.

We can remove the */* and then Accept: video/mp4 does go to mapping 1. However, we do need the */* to go to Mapping 2.

Why doesn't Accept: video/mp4 match Mapping 1 since this is a closer match?

Can we configure this endpoint to have a default method if no other accept header more closely matches? Then we could have mapping 1 only declare that it produces application/zip .

We are using Spring Boot 1.5.3.

Answer 1

Why not remove produces all together and generate the Content-Type within the method and also have an if condition to test the Accepts request header? You could call two different methods depending on the request header.

@RequestMapping(value = "endpoint", method = RequestMethod.GET)
public void doIt(HttpServletRequest request, HttpServletResponse response) {
  if (request.getHeader("Accept").matches("application/zip"))
    doZip();
  else
    doVideo();