How to create link pointing to Spring controller action that returns void

Question

I am using spring mvc, hateoas. I have a controller action that looks like

@RequestMapping(value = "/images/{userId}/{publicUrl}/{fileName:.+}", method = RequestMethod.GET)
public void image(@PathVariable Integer userId, @PathVariable String publicUrl, @PathVariable String fileName, HttpServletRequest request, HttpServletResponse response) throws Exception {
    try(HellodoxAws aws = haws;){
        .....
        .....
        response.setContentType(image.getObjectMetadata().getContentType());
        response.setHeader("ETag",image.getObjectMetadata().getETag());
        response.setHeader("Cache-Control",image.getObjectMetadata().getCacheControl());
        response.setHeader("Last-Modified",image.getObjectMetadata().getLastModified().toString());
        IOUtils.copy(image.getObjectContent(), response.getOutputStream());
    }catch (Exception e) {
        if(e instanceof AmazonS3Exception){
            int statusCode = ((AmazonS3Exception) e).getStatusCode();
            //System.out.println("Status Code : "+statusCode);
            response.setContentType("image/jpeg");
            if(statusCode==HttpStatus.NOT_MODIFIED.value()){
                response.setHeader("ETag",((AmazonS3Exception) e).getAdditionalDetails().get("ETag"));
                response.setHeader("Cache-Control",((AmazonS3Exception) e).getAdditionalDetails().get("Cache-Control"));
                response.setHeader("Last-Modified",((AmazonS3Exception) e).getAdditionalDetails().get("Last-Modified"));
            }
            response.setStatus(statusCode);
        }
    }
}

This action works perfectly well.

Now what I want is to publish url to access each profiles' image. JSON format is some thing like this

{
    "profileId" : 342308,
    "userId" : 342308,
    "firstname" : "Henry",
    "lastname" : "Seol",
    "title" : "Mr.",
    "largeImageUrl" : "https://<host>/image/<id>/<publicUrl>/<filename1.jpg>",
    "thumbImageUrl" : "https://<host>/image/<id>/<publicUrl>/<filename2.jpg>"
}

I want to add that link in place of the value for "largeImageUrl" and "thumbImageUrl".

If I use linkTo function of hateoas it says controller's corresponding method should not return void.

How to create these kind of dynamic link and add it to the resource?

Answer 1

You can use the

public static ControllerLinkBuilder linkTo(Class<?> controller, Method method, Object... parameters) {

So it should be something like

Link link = linkTo(
  ImageController.class,
  ImageController.class
    .getMethod("image", Integer.class, String.class, String.class, HttpServletRequest.class, HttpServletResponse.class),
  1,
  "url",
  "file"
).withRel("image");

Note : There is a shorter method

public static ControllerLinkBuilder linkTo(Method method, Object... parameters) {

but it has a bug therefore it does not work