Month: October 2009

When our page is idle for x amount of time the view will expire and throw javax.faces.application.ViewExpiredException to prevent this from happening
one solution is to create CustomViewHandler that extends ViewHandler
and override restoreView method all the other methods are being delegated to the Parent

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;
	}

}

Then you need to add it to your faces-config.xml

 		
com.demo.CustomViewHandler

This will prevent you from getting ViewExpiredException’s