Wicket: Merging multiple CSS files into one

CssMerger.java

package org.horsed.wicket.cssmerger;

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.apache.commons.io.FileUtils;
import org.apache.wicket.markup.head.CssContentHeaderItem;
import org.apache.wicket.markup.head.CssHeaderItem;
import org.apache.wicket.markup.head.IHeaderResponse;
import org.apache.wicket.request.resource.CssResourceReference;

public class CssMerger {

	private final String id;
	private final List<CssResourceReference> refs = new ArrayList<CssResourceReference>();

	public CssMerger(String id) {
		this.id = id;
	}

	public CssMerger addCss(Class<?> scope, String name) {
		refs.add(new CssResourceReference(scope, name));
		return this;
	}

	public CssContentHeaderItem build() {
		StringBuilder sb = new StringBuilder();
		for (CssResourceReference ref : refs) {
			try {
				String filename = ref.getResource().getResourceStream().toString().replace("file:/", "")
				    .replace("target/classes", "src/main/java");
				String style = FileUtils.readFileToString(new File(filename));
				sb.append(style);
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		return CssHeaderItem.forCSS(sb.toString(), id);
	}

	public void install(IHeaderResponse response, boolean merge) {
		if (merge) {
			response.render(this.build());
		} else {
			for (CssResourceReference ref : refs) {
				response.render(CssHeaderItem.forReference(ref));
			}
		}
	}
}

HomePage.java

package org.horsed.wicket.cssmerger;

import org.apache.wicket.markup.head.IHeaderResponse;
import org.apache.wicket.markup.html.WebPage;
import org.apache.wicket.request.mapper.parameter.PageParameters;

public class HomePage extends WebPage {

  public HomePage(final PageParameters parameters) {
		super(parameters);
	}

	@Override
	public void renderHead(IHeaderResponse response) {
		super.renderHead(response);

		new CssMerger("merged.css") //
		    .addCss(HomePage.class, "styles/style.css") //
		    .addCss(HomePage.class, "styles/comp.css") //
		    .install(response, false);
	}
}

Hello Horsed,

What about the children of the component ?

imagine you have HomePage.class that inherits another classes and those classes basically are components, so how you can merge the css files of the sub classes into one css file ?