How to handle SizeLimitExceededException from CommonsMultipartResolver in Spring WebFlow?

Question

I have the following situation. I have a CommonsMultipartResolver bean configured the following way.

<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
<property name="maxUploadSize" value="2100000" />

And I have a few file upload fields in a Spring Web Flow view state jsp.

Everything works fine if the file is under the limit, but if the file exceeds the limit of 2MB-s I have to add a validation error to the binding result on my form.

My problem is that the multipart file resolver throws a org.apache.commons.fileupload.FileUploadBase.SizeL imitExceededException exception when the file limit is exceeded and I can't find a way to catch this in Spring Web Flow and add my FieldError to the form.

I tried using the on-exception attribute of the transition tag, but if I understand correctly it only works for exceptions that are thrown within Spring Web Flow.

I've also tried to use SimpleMappingExceptionResolver in spring mvc, but I do not want to redirect to a page, I want to handle this exception.

I also found this: https://jira.springsource.org/browse/SWF-158

But it's from version 1.0 and I'm assuming that this has been incorporated since or that a better way was found to handle these situations.

Any ideas on how to deal with this would be greatly appreciated.

Thanks.

Answer 1

In your SimpleMappingExceptionResolver you should be able to override the resolveException method, determine the exception type being caught and handle appropriately.

I've found some old code in our project that seems to be a solution to a similar exception;

public class GeneralMappingExceptionResolver extends SimpleMappingExceptionResolver {

 @Override
 public ModelAndView resolveException(HttpServletRequest request, HttpServletResponse response, Object handler, Exception exception) {

    if(exception instanceof MaxUploadSizeExceededException) {
        MaxUploadSizeExceededException maxe = (MaxUploadSizeExceededException)exception;
        String errorMessage = "Max filesize exceeded, please ensure filesize is too large.");
        HashMap<String, Object> model = new HashMap<String, Object>(2);
        model.put("errorMessage", errorMessage);
        return new ModelAndView("verification/psv/consent", model);
    } else {
        return super.resolveException(request, response, handler, exception); // Do whatever default behaviour is (ie throw to error page).
    }
}

Note that the "verification/psv/consent" is the flow where this exception would have been thrown from and where it needs to return to. We only have the one page that has a file upload.

Obviously the errorMessage is just a parameter passed into the view so will need to be handled and displayed like an error message. You may also need to re-populate any other form fields that were submitted. Hopefully this is a point in the right direction though.