Spring 4 Java Config for MultipartResolver for Ser

Question

I'm taking an all-Java approach to Spring MVC configuration and cannot figure out how to associate a MultipartConfigElement with my DispatcherServlet programmatically.

Spring documentation states:

In order to use Servlet 3.0 based multipart parsing, you need to mark the DispatcherServlet with a "multipart-config" section in web.xml, or with a javax.servlet.MultipartConfigElement in programmatic Servlet registration...

http://docs.spring.io/spring/docs/4.0.4.RELEASE/spring-framework-reference/htmlsingle/#mvc-multipart

Here is my WebApplicationInitializer code:

public class DispatcherServletInitializer implements WebApplicationInitializer {

    private static final Logger logger = LoggerFactory.getLogger(DispatcherServletInitializer.class);

    @Override
    public void onStartup(ServletContext container) {

        // Create the 'root' Spring application context
        AnnotationConfigWebApplicationContext rootContext = new AnnotationConfigWebApplicationContext();
        rootContext.register(AppConfig.class);

        // Manage the lifecycle of the root application context
        container.addListener(new ContextLoaderListener(rootContext));

        // Create the dispatcher servlet's Spring application context
        AnnotationConfigWebApplicationContext dispatcherContext = new AnnotationConfigWebApplicationContext();
        dispatcherContext.register(WebConfig.class);

        //HOW CAN I ASSOCIATE THIS CONFIG WITH MY DISPATCHER SERVLET?
        MultipartConfigElement config = new MultipartConfigElement("C:\\Temp", 20848820, 418018841, 1048576);
        DispatcherServlet dispatcherServlet = new DispatcherServlet(dispatcherContext);

        // Register and map the dispatcher servlet
        ServletRegistration.Dynamic dispatcher = 
            container.addServlet("dispatcher", dispatcherServlet);
        dispatcher.setLoadOnStartup(1);
        dispatcher.addMapping("/*");
    }

}

How do I associate the MultipartConfigElement with my DispatcherServlet? I don't see any method like setMultipartConfiguration or any constructor that accepts it.

Also note that my WebConfig declares a MultipartResolver:

@Bean
public StandardServletMultipartResolver multipartResolver(){
    return new StandardServletMultipartResolver();
}

But the Spring documentation states:

Configuration settings such as maximum sizes or storage locations need to be applied at that Servlet registration level as Servlet 3.0 does not allow for those settings to be done from the MultipartResolver.

Any guidance would be greatly appreciated.

Answer 1

Here is the solution compatible with AbstractAnnotationConfigDispatcherServletInitializer way of configuring the servlet. This is a bit less invasive than WebApplicationInitializer.

It uses an override of AbstractAnnotationConfigDispatcherServletInitializer.customizeRegistration.

public class MySpringWebSetup extends AbstractAnnotationConfigDispatcherServletInitializer
{
  // Your usual obligatory configuration overrides:
  @Override protected Class<?>[] getRootConfigClasses() { ... }
  @Override protected Class<?>[] getServletConfigClasses() { ... }
  @Override protected String[] getServletMappings() { ... }

  // Optional configuration:
  @Override
  protected void customizeRegistration(Dynamic registration) {
    registration.setMultipartConfig(
      // Maybe use more sophisticated configuration than this:
      new MultipartConfigElement("")
    );
  }
}

I found it catching the stack trace of getServletMappings and thus getting into the code of org\springframework\web\servlet\support\AbstractDispatcherServletInitializer.java:

protected void registerDispatcherServlet(ServletContext servletContext) {

    [more registration stuff was here]

    registration.setLoadOnStartup(1);
    registration.addMapping(getServletMappings());
    registration.setAsyncSupported(isAsyncSupported());

    Filter[] filters = getServletFilters();
    if (!ObjectUtils.isEmpty(filters)) {
        for (Filter filter : filters) {
            registerServletFilter(servletContext, filter);
        }
    }


    customizeRegistration(registration);
}

Answer 2

Looks like you need this:

ServletRegistration.Dynamic dispatcher = 
            container.addServlet("dispatcher", dispatcherServlet);
dispatcher.setLoadOnStartup(1);
dispatcher.addMapping("/*");

dispatcher.setMultipartConfig(new MultipartConfigElement("/tmp", 1024*1024*5, 1024*1024*5*5, 1024*1024));