Portlet: Forward a ResourceRequest to show the full portal

问题:

my intention is to process a ResourceRequest that serves a resource (A dinamically generated PDF). If something goes wrong generating this file, the whole portal with a failure message in the portlet should be rendered.

Is it possible to forward a ResourceRequest to a request that renders the complete portal? I am also considering a redirect, but I will like to be able to pass some attributes/parameters along.

I hope I explained my problem clear enough. Thank you.

Related/Duplicate: How to make the ResourceResponse to forward the request to error page in liferay portlet

Example

This is an example that works and does something similar to what I want to achieve. I uses the utility class SessionErrors of Liferay: The serveResource() saves an object in the session and does a redirection to a render URL. The doView() method is called during the subsequent request and can read the contents saved in the session.

import com.liferay.portal.kernel.servlet.SessionErrors; import javax.portlet.GenericPortlet; import javax.portlet.RenderRequest; import javax.portlet.RenderResponse; import javax.portlet.ResourceRequest; import javax.portlet.ResourceResponse; import javax.portlet.PortletException; import javax.portlet.PortletException; import javax.portlet.PortletRequestDispatcher;  public class ResourceRequestForwardPortlet extends GenericPortlet {      public void serveResource(ResourceRequest request, ResourceResponse response)         throws PortletException, IOException {          SessionErrors.add(resourceRequest, "resourcerequest.error", "ERROR " + errorText);          resourceResponse.setProperty(ResourceResponse.HTTP_STATUS_CODE, "302");         resourceResponse.addProperty("Location", resourceResponse.createRenderURL().toString());     }      public void doView(RenderRequest renderRequest, RenderResponse renderResponse)         throws IOException, PortletException {          String error = (String)SessionErrors.get(renderRequest, "resourcerequest.error");         SessionErrors.clear(renderRequest);          renderRequest.setAttribute("errorMsg", error);          PortletRequestDispatcher portletRequestDispatcher = getPortletContext().getRequestDispatcher("view.jsp");         include(viewTemplate, renderRequest, renderResponse);         portletRequestDispatcher.include(renderRequest, renderResponse);     } } 

What I want to achieve is the same, but preventing the browser from doing two requests. For that, I would like to do a forward and I should write the error message as a request attribute.

I uploaded a project with this example to GitHub: https://github.com/adrianrm/poc-forward-portlet/tree/master/src/main/java/arm/requestforward

回答1:

The following is an attempt to do it using a servlet forward, and it seems to work. Still, I think it is a workaround for a feature not present in the portlet specification:

public class ResourceRequestForwardPortlet extends GenericPortlet {      public void serveResource(ResourceRequest request, ResourceResponse response)         throws PortletException, IOException {          HttpServletRequest request = PortalUtil.getOriginalServletRequest(PortalUtil.getHttpServletRequest(portletRequest));         PortletURL renderURL = portletResponse.createRenderURL();         try {             request.setAttribute("error", errorText);              String forwardURL = renderURL.toString().replace("http://localhost:8080", "");//The generation of the forwardURL could be done nicer             RequestDispatcher rd = request.getRequestDispatcher(forwardURL);             rd.forward(request, PortalUtil.getHttpServletResponse(portletResponse));         } catch (ServletException e) {             throw new PortletException(e);         }     } } 

On top of that, when the forward occurs, Liferay shows a warning on the console:

14:33:51,048 WARN  [http-apr-8080-exec-112][code_jsp:128] {code="404", msg="/poc-forward-portlet/web/guest/home", uri=/web/guest/home} X-Requested-With null 

文章来源: Portlet: Forward a ResourceRequest to show the full portal