LWK69 February 2016

Issue with Spring Security, Spring Webflow, file uploads and UTF-8

I have a problem very similar to the one described here: File Upload using Spring WebFlow 2.4.0, parameter not binded, but that one didn't mention anything about UTF-8 issues. I'm using Spring Framework 4.1.6, Spring Security 4.0.2 and Spring Webflow 2.4.2.

It revolves around StandardServletMultipartResolver vs. CommonsMultipartResolver as far as I can tell, but I'm not sure. If I use CommonsMultipartResolver I can upload files on any page except for Webflow pages fine and UTF-8 encoding works as well on all pages. However on the Webflow pages an exception is thrown trying to access the file . If I use StandardServletMultipartResolver then all of the file uploads work, including Webflow, but on any page that has a UTF-8 character, e.g., caractère, I get garbage.

The wierd thing is I can see in FireBug that the file is being posted when I use the commons resolver. Also, if I debug the RequestContext coming from Webflow I can also see the file buried 4 levels deep in requests. The code for the common resolver (see end of post for the standard resolver code):

public FileResult uploadFile(Recipe recipe, RequestContext requestContext) {
    ServletExternalContext context = (ServletExternalContext) requestContext.getExternalContext();
    MultipartHttpServletRequest multipartRequest = new DefaultMultipartHttpServletRequest((HttpServletRequest)context.getNativeRequest());
    MultipartFile file = multipartRequest.getFile("file");

So, is this a Spring Security issue or a Spring Webflow problem? I suspect the commons resolver would work if I could cast the RequestContext above correctly, but I've tried numerous combinations with no luck. Any guidance on this would be greatly appreciated.

Here are some relevant configurations and co

Answers


LWK69 February 2016

Turns out you can cast the RequestContext to get at the underlying MultipartHttpServletRequest but it's not pretty. Here's what I ended up with:

Upload file method

public FileResult uploadFile(Recipe recipe, RequestContext requestContext) {
    logger.debug("uploadFile");

    ServletExternalContext context = (ServletExternalContext) requestContext.getExternalContext();
    SecurityContextHolderAwareRequestWrapper wrapper1 = (SecurityContextHolderAwareRequestWrapper)context.getNativeRequest();
    HttpServletRequestWrapper wrapper2 = (HttpServletRequestWrapper)wrapper1.getRequest();
    FirewalledRequest firewall = (FirewalledRequest)wrapper2.getRequest();
    MultipartHttpServletRequest multipartRequest = (DefaultMultipartHttpServletRequest)firewall.getRequest();
    MultipartFile file = multipartRequest.getFile("file");
    ...rest of code to save the file...

Using this I get to keep the CommonsMultipartResolver, all file uploads in the app work whether Webflow or not, and I have no issues with UTF-8 and character mangling.

I'm not particularly happy with this solution (even though it works) since it's dependent upon a specific nesting of requests that could change in the future(?). I'm be interested if anyone else has run into the same UTF-8 issue and how they solved it, but for now I'm going to test the heck out of this and move on.

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Asked in February 2016
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