MultipartResolutionDelegate in Servlet 2.5 environments not working correctly [SPR-14461]

[spring-projects-issues]

Tobias Ahlers opened SPR-14461 and commented

As described in #18930 the MultipartResolutionDelegate has some Problems because the servletPartClass is not available (null) in Servlet 2.5 environments.

After closing #18930 I still got problems because the Method resolveMultipartArgument is called and is returning null due to

else if (isPartCollection(parameter)) {
     return (isMultipart ? RequestPartResolver.resolvePartList(request, name) : null);
}

and

private static boolean isPartCollection(MethodParameter methodParam) {
	return (servletPartClass == getCollectionParameterType(methodParam));
}

The caller (RequestParamMethodArgumentResolver) seems to expect the constant MultipartResolutionDelegate.UNRESOLVABLE instead of null:

Object mpArg = MultipartResolutionDelegate.resolveMultipartArgument(name, parameter, servletRequest);
if (mpArg != MultipartResolutionDelegate.UNRESOLVABLE) {
	return mpArg;
}

Maybe another solution approach is to always return MultipartResolutionDelegate.UNRESOLVABLE instead of null?

---

Affects: 4.3.1

Issue Links:

• Failure to resolve @RequestMapping method arguments in Servlet 2.5 environments [SPR-14358] #18930 Failure to resolve @RequestMapping method arguments in Servlet 2.5 environments

Referenced from: commits 70e666b

[spring-projects-issues]

Juergen Hoeller commented

The problem seems to be that resolveMultipartArgument may get called without isMultipartArgument having been checked first. I'll revise resolveMultipartArgument to defensively check for partClass != null as well.