Spring MVC 4 File Upload Failing Silently - spring-mvc

Question

I'm using Spring MVC (Version 4.1) on Tomcat 8, and am desperately trying to make the file upload functionality work. Currently, I have a controller configured like this:
#RequestMapping(value={"/TestCase/Upload"}, method=RequestMethod.POST)
#ResponseBody
public ResponseEntity<String> uploadFile(HttpServletRequest request,
#RequestParam("file") MultipartFile file) {
System.out.println("Hit this location.");
return new ResponseEntity("Success");
}
My web.xml has the appropriate server configuration:
<servlet>
<servlet-name>spring</servlet-name>
<servlet-class>
org.springframework.web.servlet.DispatcherServlet
</servlet-class>
<load-on-startup>1</load-on-startup>
<!-- Configuration for file upload (configuring Multipart file) -->
<multipart-config>
<location>/tmp</location>
<max-file-size>500000</max-file-size>
<max-request-size>505000</max-request-size>
<file-size-threshold>10485</file-size-threshold>
</multipart-config>
</servlet>
And finally, my Spring xml configuration file has the necessary resolver specified:
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
<property name="maxUploadSize" value="500000" />
</bean>
The Apache commons-fileupload JAR is on the classpath.
I have used this approach successfully in the past on non-Tomcat servers, but now the application isn't working - but it's failing quietly. The response has a status code of 200, but nothing inside of the file upload controller method is executed. There are no exceptions thrown in the server logs, and the only way I can get the controller method to print anything out is if I remove the "Multipart" parameter entirely. At first I thought that the controller method wasn't being hit at all, but if I change the URL mapping, then the calling code throws a 404 - so it is definitely hitting the correct mapping/method - it's just that nothing inside of the method is executing (with no exceptions thrown!)
What am I doing wrong?

Answer 1

It turns out Spring MVC will hide noClassDef's from the console when booting itself up. The issue was that apache-commons-io.jar was missing on the classpath. Including that JAR caused everything to work properly.
So in the future if Spring is quietly misbehaving - check to ensure all necessary libraries are explicitly included, because it certainly won't tell you!