How to catch all unhandled exceptions (i.e. without existing @ExceptionHandler) in Spring MVC?

Question

I want to let HandlerExceptionResolver resolve any Exceptions that I don't explicit catch via @ExceptionHandler annotation.

Anyways, I want to apply specific logic on those exceptions. Eg send a mail notification or log additionally. I can achieve this by adding a @ExceptionHandler(Exception.class) catch as follows:

@RestControllerAdvice
public MyExceptionHandler {
    @ExceptionHandler(IOException.class)
    @ResponseStatus(HttpStatus.BAD_REQUEST)
    public Object io(HttpServletRequest req, Exception e) {
        return ...
    }


    @ExceptionHandler(Exception.class)
    public Object exception(HttpServletRequest req, Exception e) {
        MailService.send();
        Logger.logInSpecificWay();

        //TODO how to continue in the "normal" spring way with HandlerExceptionResolver?
    }
}

Problem: if I add @ExceptionHandler(Exception.class) like that, I can catch those unhandled exceptions.

BUT I cannot let spring continue the normal workflow with HandlerExceptionResolver to create the response ModelAndView and set a HTTP STATUS code automatically.

Eg if someone tries a POST on a GET method, spring by default would return a 405 Method not allowed. But with an @ExceptionHandler(Exception.class) I would swallow this standard handling of spring...

So how can I keep the default HandlerExceptionResolver, but still apply my custom logic?

Answer 1

To provide a complete solution: it works just by extending ResponseEntityExceptionHandler, as that handles all the spring-mvc errors. And the ones not handled can then be caught using @ExceptionHandler(Exception.class).

@RestControllerAdvice
public class MyExceptionHandler extends ResponseEntityExceptionHandler {
    @ExceptionHandler(Exception.class)
    public ResponseEntity<Object> exception(Exception ex) {
        MailService.send();
        Logger.logInSpecificWay();
        return ... custom exception 
    }
}

Answer 2

Well, I was facing the same problem some time back and have tried several ways like extending ResponseEntityExceptionHandler but all them were solving some problems but creating other ones.

Then I have decided to go with a custom solution which was also allowing me to send additional information and I have written below code

@RestControllerAdvice
public class MyExceptionHandler {

    private final Logger log = LoggerFactory.getLogger(this.getClass());

    @ExceptionHandler(NumberFormatException.class)
    public ResponseEntity<Object> handleNumberFormatException(NumberFormatException ex) {
        return new ResponseEntity<>(getBody(BAD_REQUEST, ex, "Please enter a valid value"), new HttpHeaders(), BAD_REQUEST);
    }

    @ExceptionHandler(IllegalArgumentException.class)
    public ResponseEntity<Object> handleIllegalArgumentException(IllegalArgumentException ex) {
        return new ResponseEntity<>(getBody(BAD_REQUEST, ex, ex.getMessage()), new HttpHeaders(), BAD_REQUEST);
    }

    @ExceptionHandler(AccessDeniedException.class)
    public ResponseEntity<Object> handleAccessDeniedException(AccessDeniedException ex) {
        return new ResponseEntity<>(getBody(FORBIDDEN, ex, ex.getMessage()), new HttpHeaders(), FORBIDDEN);
    }

    @ExceptionHandler(Exception.class)
    public ResponseEntity<Object> exception(Exception ex) {
        return new ResponseEntity<>(getBody(INTERNAL_SERVER_ERROR, ex, "Something Went Wrong"), new HttpHeaders(), INTERNAL_SERVER_ERROR);
    }

    public Map<String, Object> getBody(HttpStatus status, Exception ex, String message) {

        log.error(message, ex);

        Map<String, Object> body = new LinkedHashMap<>();
        body.put("message", message);
        body.put("timestamp", new Date());
        body.put("status", status.value());
        body.put("error", status.getReasonPhrase());
        body.put("exception", ex.toString());

        Throwable cause = ex.getCause();
        if (cause != null) {
            body.put("exceptionCause", ex.getCause().toString());
        }
        return body;
    }

}