This feature is a very simple and useful in AJAX and JSON like things.  It is a way to get pure response code as you set.

1. TestResourcePortle.java

public class TestResourcePortlet implements Portlet, ResourceServingPortlet {

......

    public void serveResource(ResourceRequest resourceRequest,
            ResourceResponse resourceResponse) throws PortletException,
            IOException {
        PortletRequestDispatcher portletRequestDispatcher = portletConfig
                .getPortletContext().getRequestDispatcher(
                        "/WEB-INF/jsp/resource.jsp");
        portletRequestDispatcher.include(resourceRequest, resourceResponse);
    }

........

}

2. view.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%>
<%@taglib prefix="portlet" uri="http://java.sun.com/portlet_2_0"%>
<portlet:defineObjects />
<a href="<portlet:resourceURL/>">Resource URL</a></td>

3. resources.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%>
<%@taglib prefix="portlet" uri="http://java.sun.com/portlet_2_0"%>
<portlet:defineObjects />
portlet resource page