PropertyResourceBundleControl

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URL;
import java.net.URLConnection;
import java.security.AccessController;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.text.MessageFormat;
import java.util.Locale;
import java.util.PropertyResourceBundle;
import java.util.ResourceBundle;
import java.util.ResourceBundle.Control;

public class CharsetSupportedControl extends Control {

    private String charset;

    public CharsetSupportedControl() {
        this("utf-8");
    }

    public CharsetSupportedControl(String charset) {
        this.charset = charset;
    }

    @Override
    public ResourceBundle newBundle(String baseName, Locale locale, String format, ClassLoader loader, boolean reload)
            throws IllegalAccessException, InstantiationException, IOException {
        if (format.equals("java.class")) {
            return super.newBundle(baseName, locale, format, loader, reload);
        } else if (format.equals("java.properties")) {
            String bundleName = toBundleName(baseName, locale);
            final String resourceName = toResourceName(bundleName, "properties");
            final ClassLoader classLoader = loader;
            final boolean reloadFlag = reload;
            InputStream stream = null;
            try {
                stream = AccessController.doPrivileged(
                    new PrivilegedExceptionAction<InputStream>() {
                        public InputStream run() throws IOException {
                            InputStream is = null;
                            if (reloadFlag) {
                                URL url = classLoader.getResource(resourceName);
                                if (url != null) {
                                    URLConnection connection = url.openConnection();
                                    if (connection != null) {
                                        // Disable caches to get fresh data for
                                        // reloading.
                                        connection.setUseCaches(false);
                                        is = connection.getInputStream();
                                    }
                                }
                            } else {
                                is = classLoader.getResourceAsStream(resourceName);
                            }
                            return is;
                        }
                    });
            } catch (PrivilegedActionException e) {
                throw (IOException) e.getException();
            }
            if (stream != null) {
                try {
                    BufferedReader br = new BufferedReader(new InputStreamReader(stream, charset));
                    try {
                        return new PropertyResourceBundle(br);
                    } finally {
                        br.close();
                    }
                } finally {
                    stream.close();
                }
            }
            
            return null;
        } else {
            throw new IllegalArgumentException("unknown format: " + format);
        }
    }

    public static void main(String[] args) throws Exception {
        // message.properties をクラスパス直下に
        ResourceBundle bundle = ResourceBundle.getBundle("messages", new CharsetSupportedControl());
        System.out.println(bundle.getString("message"));
    }
}