Exclude resources in JSF - jsf

Question

I'm using Primefaces. For some pages I want to exclude the resources which are included by primefacs, especially the theme resource.
<link type="text/css" rel="stylesheet" href="/context/javax.faces.resource/theme.css?ln=primefaces-owntheme" />
I try that with a SystemEventListener as following:
public class PrimeFacesResourceRemover implements javax.faces.event.SystemEventListener {
#Override
public void processEvent(SystemEvent event) throws AbortProcessingException {
FacesContext context = FacesContext.getCurrentInstance();
UIViewRoot viewRoot = context.getViewRoot();
for (UIComponent resource : viewRoot.getComponentResources(context, "head")) {
Map<String, Object> attrs = resource.getAttributes();
String resourceLibrary = (String) attrs.get("library");
String resourceName = (String) attrs.get("name");
if ("primefaces-owntheme".equals(resourceLibrary) && "theme.css".equals(resourceName)) {
// Remove resource from view
context.getViewRoot().removeComponentResource(context, resource, HEAD);
}
}
}
/**
* {#inheritDoc}
*/
#Override
public boolean isListenerForSource(Object source) {
return (source instanceof UIViewRoot);
}
}
and in the faces-config.xml
<application>
<system-event-listener>
<system-event-listener-class>
com.mycompany.mavenproject1.PrimeFacesResourceRemover
</system-event-listener-class>
<system-event-class>
javax.faces.event.PostAddToViewEvent
</system-event-class>
</system-event-listener>
</application>
This works well, when I include a resouce on a page manually, but those not work with the resouces which are included by Primefaces. How can I remove those resouces?

Answer 1

The theme.css is not been added as a dynamic component resource, but it's been hardcoded in PrimeFaces' HeadRenderer. The OmniFaces CombinedResourceHandler was also struggling with this.
The solution is rather simple: override it with a custom HeadRenderer (without any #ResourceDependency on theme.css, of course!):
public class HeadRenderer extends Renderer {
#Override
public void encodeBegin(FacesContext context, UIComponent component) throws IOException {
context.getResponseWriter().startElement("head", component);
}
#Override
public void encodeChildren(FacesContext context, UIComponent component) throws IOException {
// NOOP.
}
#Override
public void encodeEnd(FacesContext context, UIComponent component) throws IOException {
for (UIComponent resource : context.getViewRoot().getComponentResources(context, "head")) {
resource.encodeAll(context);
}
context.getResponseWriter().endElement("head");
}
}
Register it as follows in webapp's faces-config.xml:
<render-kit>
<renderer>
<component-family>javax.faces.Output</component-family>
<renderer-type>javax.faces.Head</renderer-type>
<renderer-class>com.example.HeadRenderer</renderer-class>
</renderer>
</render-kit>

Answer 2

For all of you who would like to remove theme.css on all pages (that's the first thing I am doing), and still don't know this trick.
You'll need to drop these few lines in your web.xml:
<context-param>
<param-name>primefaces.THEME</param-name>
<param-value>none</param-value>
</context-param>