bundlehandler.java

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package org.kdb.util;

import java.lang.reflect.Method;
import java.util.*;

/**

 * Date: 2007-11-5
 * Time: 9:26:01
 */
public class BundleHandler {
    /**
     * Used to synchronize access
     */
    private static final Object mutex = new Object();

    /**
     * The Locale used internally to fetch resource bundles.
     */
    private static Locale locale = Locale.getDefault();

    /**
     * Map:  Integer object handle => <code>ResourceBundle</code> object.
     */
    private static HashMap bundleHandleMap = new HashMap();

    /**
     * List whose elements are <code>ResourceBundle</code> objects
     */
    private static ArrayList bundleList = new ArrayList();

    /**
     * The resource path prefix of the <code>ResourceBundle</code> objects
     * handled by this class.
     */
    private static final String prefix = "org/kdb/util/";

    /**
     * JDK 1.1 compliance
     */
    private static final Method newGetBundleMethod = getNewGetBundleMethod();

    /**
     * Pure utility class: external construction disabled.
     */
    private BundleHandler() {
    }

    /**
     * Getter for property locale. <p>
     *
     * @return Value of property locale.
     */
    public static Locale getLocale() {

        synchronized (mutex) {
            return locale;
        }
    }

    /**
     * Setter for property locale. <p>
     *
     * @param l the new locale
     * @throws IllegalArgumentException when the new locale is null
     */
    public static void setLocale(Locale l) throws IllegalArgumentException {

        synchronized (mutex) {
            if (l == null) {
                throw new IllegalArgumentException("null locale");
            }

            locale = l;
        }
    }

    /**
     * Retrieves an <code>int</code> handle to the <code>ResourceBundle</code>
     * object corresponding to the specified name and current
     * <code>Locale</code>, using the specified <code>ClassLoader</code>. <p>
     *
     * @param cl   The ClassLoader to use in the search
     * @param name of the desired bundle
     * @return <code>int</code> handle to the <code>ResourceBundle</code>
     *         object corresponding to the specified name and
     *         current <code>Locale</code>, or -1 if no such bundle
     *         can be found
     */
    public static int getBundleHandle(String name, ClassLoader cl) {

        Integer bundleHandle;
        ResourceBundle bundle;
        String bundleName;
        String bundleKey;

        bundleName = prefix + name;

        synchronized (mutex) {
            bundleKey = locale.toString() + bundleName;
            bundleHandle = (Integer) bundleHandleMap.get(bundleKey);

            if (bundleHandle == null) {
                try {
                    bundle = getBundle(bundleName, locale, cl);

                    bundleList.add(bundle);

                    bundleHandle = new Integer(bundleList.size() - 1);

                    bundleHandleMap.put(bundleKey, bundleHandle);
                } catch (Exception e) {

                    //e.printStackTrace();
                }
            }
        }

        return bundleHandle == null ? -1
                : bundleHandle.intValue();
    }

    /**
     * Retrieves, from the <code>ResourceBundle</code> object corresponding
     * to the specified handle, the <code>String</code> value corresponding
     * to the specified key.  <code>null</code> is retrieved if either there
     * is no <code>ResourceBundle</code> object for the handle or there is no
     * <code>String</code> value for the specified key. <p>
     *
     * @param handle an <code>int</code> handle to a
     *               <code>ResourceBundle</code> object
     * @param key    A <code>String</code> key to a <code>String</code> value
     * @return The String value correspoding to the specified handle and key.
     */
    public static String getString(int handle, String key) {

        ResourceBundle bundle;
        String s;

        synchronized (mutex) {
            if (handle < 0 || handle >= bundleList.size() || key == null) {
                bundle = null;
            } else {
                bundle = (ResourceBundle) bundleList.get(handle);
            }
        }

        if (bundle == null) {
            s = null;
        } else {
            try {
                s = bundle.getString(key);
            } catch (Exception e) {
                s = null;
            }
        }

        return s;
    }

    /**
     * One-shot initialization of JDK 1.2+ ResourceBundle.getBundle() method
     * having ClassLoader in the signature.
     */
    private static Method getNewGetBundleMethod() {

        Class clazz;
        Class[] args;

        clazz = ResourceBundle.class;
        args = new Class[]{
                String.class, Locale.class, ClassLoader.class
        };

        try {
            return clazz.getMethod("getBundle", args);
        } catch (Exception e) {
            return null;
        }
    }

    /**
     * Retrieves a resource bundle using the specified base name, locale, and
     * class loader. This is a JDK 1.1 compliant substitution for the
     * ResourceBundle method with the same name and signature. If there
     * is a problem using the JDK 1.2 functionality (the class loader is
     * specified non-null and the underlying method is not available or there
     * is a security exception, etc.), then the behaviour reverts to that
     * of JDK 1.1.
     *
     * @param name   the base name of the resource bundle, a fully
     *               qualified class name
     * @param locale the locale for which a resource bundle is desired
     * @param cl     the class loader from which to load the resource bundle
     */
    public static ResourceBundle getBundle(String name, Locale locale,
                                           ClassLoader cl)
            throws NullPointerException,
            MissingResourceException {

        if (cl == null) {
            return ResourceBundle.getBundle(name, locale);
        } else if (newGetBundleMethod == null) {
            return ResourceBundle.getBundle(name, locale);
        } else {
            try {
                return (ResourceBundle) newGetBundleMethod.invoke(null,
                        new Object[]{
                                name, locale, cl
                        });
            } catch (Exception e) {
                return ResourceBundle.getBundle(name, locale);
            }
        }
    }
}