Spring exception handler outside controller

Question

In @ControllerAdvice class I have an @ExceptionHandler, this handler works well with controller errors but if I have a filter they can't handle the exception. How can I handle these exceptions?

The filter is:-

public class AuthFilter extends UsernamePasswordAuthenticationFilter {

    private LoginDTO loginDTO;

    public AuthFilter() {
        setRequiresAuthenticationRequestMatcher(
                new AntPathRequestMatcher("/login", "POST"));
    }

    @Override
    public Authentication attemptAuthentication(HttpServletRequest request,
            HttpServletResponse response) throws AuthenticationException {

        try {
            loginDTO = new ObjectMapper().readValue(request.getReader(), LoginDTO.class);
        } catch (Exception e) {
            throw new APIException(ExceptionMessages.INVALID_LOGIN_JSON,
                    HttpStatus.BAD_REQUEST);
        }

        return super.attemptAuthentication(request, response);
    }

    ...
}

The exception handler is (in @ControllerAdvice)

    @ExceptionHandler(APIException.class)
    public ResponseEntity<ErrorDTO> handleAPIException(APIException e) {
        return new ResponseEntity<ErrorDTO>(new ErrorDTO(e.getMessage()),
                e.getHttpStatus());
    }

UPDATE

My requirement is having a global exception handler for spring security filters. Is there any way to do it?

Answer 1

I'm afraid you cannot. Here is (broadly) how à request is processed in a Spring MVC web application :

servlet container
    filters before FilterChain.doFilter
        DispatcherServlet  => here is all Spring MVC machinery
    filters after FilterChain.doFilter
servlet container

All Spring MVC machinery is managed inside the DispatcherServlet, including all exception handling.

IMHO, you can try two things :

• replace the filter with an interceptor (*)
• use another filter coming before the one where exception is thrown and catch it there (the non Spring MVC way, but filters are outside of Spring MVC)

(*) You will still not be able to use an ExceptionHandler since exception will be thrown outside of a controller, but you could use a HandlerExceptionResolver.