public static UIViewRoot findRoot(FacesContext context, ServletRequest req, Object etag)
throws Exception {
if (context == null) context = FacesContext.getCurrentInstance();
UIViewRoot root = context.getViewRoot();
if (root == null)
throw new NullPointerException(L.l("f:view can't find current in FacesContext"));
Object oldETag = root.getAttributes().get("caucho.etag");
if (oldETag != null && !oldETag.equals(etag)) {
// clear view on JSP change
root.getChildren().clear();
root.getFacets().clear();
}
root.getAttributes().put("caucho.etag", etag);
return root;
}
