ResponseStatusExceptionResolver ignores ResponseStatusException headers

[michael-o]

Affects: Spring Framework 5.2.5.RELEASE

---

When throwing a derived exception like:

	public class NotModifiedStatusException extends ResponseStatusException {

		private static final long serialVersionUID = -4380761922076567306L;

		private String etag;

		public NotModifiedStatusException(String etag) {
			super(HttpStatus.NOT_MODIFIED);
			this.etag = etag;
		}

		@Override
		public Map<String, String> getHeaders() {
			return getResponseHeaders().toSingleValueMap();
		}

		@Override
		public HttpHeaders getResponseHeaders() {
			HttpHeaders headers = new HttpHeaders();
			headers.setETag(etag);
			return headers;
		}

	}

the headers are completely ignored:

17:56:01,681 [http-nio-127.0.0.1-8081-exec-5] DEBUG o.s.w.s.m.a.ResponseStatusExceptionResolver: Resolved [...NotModifiedStatusException: 304 NOT_MODIFIED]
17:56:01,681 [http-nio-127.0.0.1-8081-exec-5] TRACE o.s.web.servlet.DispatcherServlet: No view rendering, null ModelAndView returned.
17:56:01,681 [http-nio-127.0.0.1-8081-exec-5] DEBUG o.s.web.servlet.DispatcherServlet: Completed 304 NOT_MODIFIED, headers={}

It happily ignores the headers:

spring-framework/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/annotation/ResponseStatusExceptionResolver.java

Lines 128 to 133 in 8d31dca

	protected ModelAndView resolveResponseStatusException(ResponseStatusException ex,
	HttpServletRequest request, HttpServletResponse response, @Nullable Object handler) throws Exception {
	int statusCode = ex.getStatus().value();
	String reason = ex.getReason();
	return applyStatusAndReason(statusCode, reason, response);

My naive solution seems to work:

@Component
public class HeaderAwareResponseStatusExceptionResolver extends ResponseStatusExceptionResolver {

	@Override
	public int getOrder() {
		return super.getOrder() + 1;
	}

	@Override
	protected ModelAndView resolveResponseStatusException(ResponseStatusException ex,
			HttpServletRequest request, HttpServletResponse response, Object handler)
			throws Exception {
		int statusCode = ex.getStatus().value();
		String reason = ex.getReason();
		HttpHeaders headers = ex.getResponseHeaders();

		headers.forEach((name, values) -> values.forEach(value -> response.addHeader(name, value)));

		if (!StringUtils.hasLength(reason)) {
			response.sendError(statusCode);
		} else {
			response.sendError(statusCode, reason);
		}
		return new ModelAndView();
	}

}

[rstoyanchev]

Support for headers was added recently in #24261 but only on the WebFlux side it seems.

[michael-o]

Correct, this is my observation. I assume this is simply an oversight.

[michael-o]

The provided solution is in consistent with the Flux version:

spring-framework/spring-web/src/main/java/org/springframework/web/server/handler/ResponseStatusExceptionHandler.java

Lines 94 to 97 in ea6d2ea

	if (ex instanceof ResponseStatusException) {
	((ResponseStatusException) ex).getResponseHeaders()
	.forEach((name, values) ->
	values.forEach(value -> response.getHeaders().add(name, value)));

It does not contain a null check.

[rstoyanchev]

Yes it is a little more defensive. Spring MVC has been around longer and is used more widely. Do you foresee an issue?

[michael-o]

Not right now, but this deserves to be documented.

[rstoyanchev]

I've updated it to match WebMvc.