how to register filter class in WebApplicationInitializer

public class MyWebAppInitializer implements WebApplicationInitializer {

   @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(DispatcherConfig.class);

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

}