Spring MVC @ExceptionHandler method in controller never being invoked

Question

I have a Spring MVC controller with some simple REST service requests. I would like to add some error handling when specific exceptions are thrown from my services, but I cannot get a handler method annotated with @ExceptionHandler to actually ever be called. Here is one service I am deliberately throwing an exception to try and get my handler method to take over. The handler method is never invoked and Spring just returns a 500 error to the calling client. Do you have any ideas on what I'm doing wrong?

@ExceptionHandler(IOException.class)
public ModelAndView handleIOException(IOException ex, HttpServletRequest request, HttpServletResponse response) {
    response.sendError(HttpServletResponse.SC_FORBIDDEN);
    System.out.println("It worked!");
    return new ModelAndView();
}

@RequestMapping(value = "/json/remove-service/{id}", method = RequestMethod.DELETE)
public void remove(@PathVariable("id") Long id) throws IOException {
    throw new IOException("The handler should take over from here!");
}

Answer 1

Frustratingly, I have suffered from this as well. I discovered that if you mistakenly implement Throwable instead of Exception the Exception resolver will just rethrow your Throwable as a IllegalStateException. This will fail to invoke your @ExceptionHandler.

If you've implemented Throwable instead of Exception try changing it to Exception instead.

Here's the code in question from InvocableHandlerMethod

catch (InvocationTargetException e) {
            // Unwrap for HandlerExceptionResolvers ...
            Throwable targetException = e.getTargetException();
            if (targetException instanceof RuntimeException) {
                throw (RuntimeException) targetException;
            }
            else if (targetException instanceof Error) {
                throw (Error) targetException;
            }
            else if (targetException instanceof Exception) {
                throw (Exception) targetException;
            }
            else {
                String msg = getInvocationErrorMessage("Failed to invoke controller method", args);
                throw new IllegalStateException(msg, targetException);
            }
        }