从xhtml文件创建jsf视图/组件树

Question

I need to access jsf pages component tree on application start up. I found this source on the net

   UIViewRoot viewRoot = context.getApplication().getViewHandler().createView(context, "/path/to/some.xhtml");

but the resulting viewRoot doesn't have any children. Does anybody know what is the best way to do it?

thanks.

Answer 1

You forgot to build the view. You can use ViewDeclarationLanguage#buildView() for this. Here's an extract of its javadoc (emphasis mine):

Take any actions specific to this VDL implementation to cause the argument UIViewRoot which must have been created via a call to createView(javax.faces.context.FacesContext, java.lang.String) , to be populated with children .

Thus, this should do:

String viewId = "/path/to/some.xhtml";
FacesContext context = FacesContext.getCurrentInstance();
ViewHandler viewHandler = context.getApplication().getViewHandler();

UIViewRoot view = viewHandler.createView(context, viewId);
viewHandler.getViewDeclarationLanguage(context, viewId).buildView(context, view);
// view should now have children.

You can by the way also use the ViewDeclarationLanguage#createView() directly to create the view instead of the ViewHandler#createView() shorthand.

String viewId = "/path/to/some.xhtml";
FacesContext context = FacesContext.getCurrentInstance();
ViewDeclarationLanguage vdl = context.getApplication().getViewHandler().getViewDeclarationLanguage(context, viewId);

UIViewRoot view = vdl.createView(context, viewId);
vdl.buildView(context, view);
// view should now have children.