Intercept @RequestHeader exception for missing header

Question

I have a method in controller with has parameter for example

@RequestMapping(value = "/{blabla}", method = RequestMethod.POST)
@ResponseStatus(HttpStatus.CREATED)
public void post(@RequestHeader("ETag") int etag)

If there is no ETag header in request - client gets 400 (BAD_REQUEST), which is not any informative. I need to somehow handle this exception and send my own exception to client (I use JSON for this purpose). I know that I can intercept exception via @ExceptionHandler, but in that case all HTTP 400 requests will be handled, but I want that have missing ETag in headers. Any ideas?

Answer 1

In case Spring version is 5+ then the exact exception you need to handle is the MissingRequestHeaderException. If your global exception handler class extends ResponseEntityExceptionHandler then adding an @ExceptionHandler for ServletRequestBindingException won't work because MissingRequestHeaderException extends ServletRequestBindingException and the latter is handled inside the handleException method of the ResponseEntityExceptionHandler. If you try you're going to get Ambiguous @ExceptionHandler method mapped for ... exception.