import java.io.IOException;
import javax.faces.FacesException;
import javax.faces.application.ViewHandler;
import javax.faces.component.UIViewRoot;
import javax.faces.context.FacesContext;
import javax.servlet.http.HttpServletRequest;
 
public class CustomViewHandler extends ViewHandler {
	private ViewHandler parent;
 
	public CustomViewHandler(ViewHandler parent) {
		//System.out.println("CustomViewHandler.CustomViewHandler():Parent View Handler:"+parent.getClass());
		this.parent = parent;
	}
 
    @Override public UIViewRoot restoreView(FacesContext facesContext, String viewId) {
	/**
	 * {@link javax.faces.application.ViewExpiredException}. This happens only  when we try to logout from timed out pages.
	 */
	UIViewRoot root =null; 
	root = parent.restoreView(facesContext, viewId);
	if(root == null) {			
		root = createView(facesContext, viewId);
	}
	return root;
 }
 
 @Override
	public Locale calculateLocale(FacesContext facesContext) {
		return parent.calculateLocale(facesContext);
	}
 
	@Override
	public String calculateRenderKitId(FacesContext facesContext) {
		String renderKitId = parent.calculateRenderKitId(facesContext);
		//System.out.println("CustomViewHandler.calculateRenderKitId():RenderKitId: "+renderKitId);
		return renderKitId;
	}
 
	@Override
	public UIViewRoot createView(FacesContext facesContext, String viewId) {
		return parent.createView(facesContext, viewId);
	}
 
 
    @Override
	public String getActionURL(FacesContext facesContext, String actionId) {
		return parent.getActionURL(facesContext, actionId);
	}
 
	@Override
	public String getResourceURL(FacesContext facesContext, String resId) {
		return parent.getResourceURL(facesContext, resId);
	}
 
	@Override
	public void renderView(FacesContext facesContext, UIViewRoot viewId) throws IOException, FacesException {
		parent.renderView(facesContext, viewId);
 
	}
 
	@Override
	public void writeState(FacesContext facesContext) throws IOException {
		parent.writeState(facesContext);
	}
 
	public ViewHandler getParent() {
		return parent;
	}
 
}

<view-handler>com.demo.CustomViewHandler</view-handler>

11 Responses to “Preventing ViewExpiredException in JSF”

1. Kashif Says:
   October 25th, 2009 at 11:23 pm

   Hi, I am trying to implement this example but not sure where does the object ‘parent’ come from. Please help me.

   Regards,
   Kashif

2. Greg Says:
   October 27th, 2009 at 8:24 am

   Parent comes from the ViewHandler constructor, also there are other methods that can be overwritten if you like.
   
private ViewHandler parent;

   public CustomViewHandler(ViewHandler parent) {
//System.out.println("CustomViewHandler.CustomViewHandler():Parent View Handler:"+parent.getClass());
this.parent = parent;
}

   Hope this helps, also I will update the post with this.

3. Pepe Says:
   November 18th, 2009 at 10:41 am

   Hi I tried this example and I get failure. It is due to the spread of ViewHanler you add other methods that do not what to do with them. In asking that page shows me what I’m doing gives me an error java.lang.NullPointerException: renderKitId

   I’m a little awkward and not what you have to do. Please help.

4. Greg Says:
   November 18th, 2009 at 12:28 pm

   I have updated the example with the other overwritten methods that should fix your problem.
   If you still having issues post your code for your Custom ViewHandler

5. Pepe Says:
   November 19th, 2009 at 2:57 am

   Thank you very much, Greg.

6. Greg Says:
   November 19th, 2009 at 5:56 pm

   No problem I hope this helps you.

7. Amit Kumar Says:
   July 23rd, 2010 at 3:38 am

   Great work man :). It is the simplest working solution. Thanks.

8. Greg Says:
   July 23rd, 2010 at 9:07 am

   Thanks

9. Alex Says:
   August 12th, 2010 at 8:04 am

   If you’re using Facelets you can extend FaceletViewHandler and just have the restoreView() method. In my case I also return an error/information page if root == null. I think it’s more user friendly. Here’s the code:

   public class MyFaceletViewHandler extends FaceletViewHandler {
    
       public MyFaceletViewHandler(ViewHandler parent) {
           super(parent);
       }
    
       @Override
       public UIViewRoot restoreView(FacesContext facesContext, String viewId) {
           UIViewRoot root = super.restoreView(facesContext, viewId);
           // do not allow ViewExpiredException
           if (root == null) {
               root = createView(facesContext, "/viewExpired.xhtml");
               facesContext.renderResponse();
           }
           return root;
       }
    
   }

10. Romeo Says:
    August 17th, 2010 at 2:59 pm

    Thanks for the solution. But I still do have some problems getting around my basic issue.
    I have a secured application (Spring security), with a simple login form. I can happen fairly often that the user opens the login page and leaves the browser open without performing a login.
    The session times out and when the user tries to login he would get a ViewExpiredException.
    Displaying a session-time-out-page makes no sense, the user was at the start page and overriding the ViewExpiredException-behaviour for this single, simple issue seems like a dangerous overkill for me.
    Is there any other way telling JSF this is the start page, we do not need a stored view for this??? I have read numerous articles about this and it has been bugging me for nearly a year(!) that you need to make fairly big changes in the JSF-ecosystem for imho a very, very common problem.
    Where am I wrong?

11. Greg Says:
    August 19th, 2010 at 8:38 am

    You might want to use

     
        javax.faces.application.ViewExpiredException
        /sessionExpired.jsf

    in you faces-config.xml it might work for you. There is also a way of defining on how to catch errors in web.xml

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