Liferay Portlet and JSF : Redirect during Render Phase

问题

I have a problem to implement a simple HTTP redirection.

I use Liferay 6.0.6, our portlets are build with JSF2.0 / PortletFaces.

I want to call a redirection when a view is loaded (and not when an action is triggered). Currently, my function is called by the PreRenderView listener.

<f:metadata>
  <f:event listener="#{myControler.dispatch}" type="preRenderView" />
</f:metadata>

In this function, i can check the permissions, do other stuff, and in some cases I want to redirect the user to a new page (not another view).

I tried several methods, unsuccessfully. Specifically, I thought that this method would work :

getFacesContext().getExternalContext().redirect(url);
getFacesContext().responseComplete()
// => Can only redirect during ACTION_PHASE

This error is logical, but is there a solution to force the redirection.

It could be realized in another function, called otherwise, I only need the Hibernate Session (set at the beginning of the Render Phase)

Have you ideas to resolve this problem?
Thanks!

ps : <redirect /> or ?faces-redirect don't work with the portlets.

回答1:

You can't do this in the render phase by design. Reasons:

• It's possible that portlets are rendered asynchronously, so the page might already be displayed when your portlet is being rendered
• It's possible that parts of the page are already delivered to the client, so that the HTTP Headers are already sent - for this reason, by design you don't have access to them in the render phase
• What would be the expected outcome if two portlets rendered on the same page would decide that they'd like to forwards to another page? Who would win?

A hacky workaround is to render some javascript redirect, but this is veeeery un-portal-like and can mess up other's expectations (plus, parts of the page might already be rendered, causing your users to fill a form only to be redirected by your javascript routine.

Please rethink the problem and come up with a different solution - it's really worth doing this in a portal environment.

回答2:

Use the below method it will work

public static void redirect(final String url) throws IOException {

            final javax.portlet.PortletResponse portletResponse
            = getPortletResponse();

            if (portletResponse instanceof ActionResponse) {

                final javax.portlet.ActionResponse actionResponse
                = (javax.portlet.ActionResponse) portletResponse;

                actionResponse.sendRedirect(url);

            } else if (portletResponse instanceof ResourceResponse) {

                final FacesContext ctx = FacesContext.getCurrentInstance();
                if (ctx.getPartialViewContext().isPartialRequest()) {

                    final ResourceResponse portletResResp
                    = (ResourceResponse) portletResponse;
                    PartialResponseWriter pwriter;
                    final ResponseWriter writer = ctx.getResponseWriter();
                    if (writer instanceof PartialResponseWriter) {
                        pwriter = (PartialResponseWriter) writer;
                    } else {
                        pwriter = ctx.getPartialViewContext()
                        .getPartialResponseWriter();
                    }
                    portletResResp.setContentType(Constants.CONTENT_TYPE);
                    portletResResp.setCharacterEncoding(Constants.ENCODING_TYPE);
                    // addResponseHeader("Cache-Control", "no-cache");
                    pwriter.startDocument();
                    pwriter.redirect(url);
                    pwriter.endDocument();
                    ctx.responseComplete();
                } else {
                    throw new UnsupportedEncodingException(
                            "Can only redirect during RESOURCE_PHASE "
                            + "if a Partial-(JSF AJAX)-Request  has "
                            + "been triggered");
                }
            } else {
                throw new UnsupportedEncodingException(
                        "Can not redirect during the current phase: "
                        + portletResponse.getClass().getSimpleName());
            }
        }

回答3:

I use this and it works for me:

    public void preRenderView() throws IOException {

        if (!checkUtente()) {  

              FacesContext fc = FacesContext.getCurrentInstance(); 

              NavigationHandler navigationHandler = fc.getApplication().getNavigationHandler();

              navigationHandler.handleNavigation(fc, null, "errore.xhtml?faces-redirect=true");

              fc.renderResponse(); 
        }

    }

来源：https://stackoverflow.com/questions/6878828/liferay-portlet-and-jsf-redirect-during-render-phase