A ResourceBundle Control for reading files off a ServletContext.

ServletContextBundleControl.java

package nz.co.aetheric.web.servlet;

import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;

import javax.servlet.ServletContext;
import java.io.IOException;
import java.io.InputStream;
import java.security.AccessController;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.util.Locale;
import java.util.PropertyResourceBundle;
import java.util.ResourceBundle;

/**
 * This class controls the way that resource bundles are loaded from the servlet context instead of the class loader.
 * <p>Author: <a href="http://gplus.to/tzrlk">Peter Cummuskey</a></p>
 */
@Slf4j
@RequiredArgsConstructor
public class ServletContextBundleControl extends ResourceBundle.Control {

	protected final ServletContext context;

	@Override
	public ResourceBundle newBundle(String baseName, Locale locale, String format, ClassLoader loader, boolean reload)
		throws IllegalAccessException, InstantiationException, IOException {

		final String path = toBundleName(baseName, locale) + ".properties";
		final PrivilegedResourceLoad privileged = new PrivilegedResourceLoad(path);

		try (InputStream stream = privileged.perform()) {
			return stream != null
					? new PropertyResourceBundle(stream)
					: null;
		}

	}

	@RequiredArgsConstructor
	public class PrivilegedResourceLoad implements PrivilegedExceptionAction<InputStream> {

		protected final String resource;

		@Override
		public InputStream run() throws IOException {
			return context.getResourceAsStream(resource);
		}

		public InputStream perform() throws IOException {
			try {
				return AccessController.doPrivileged(this);
			} catch (PrivilegedActionException error) {
				throw (IOException) error.getCause();
			}
		}

	}

}