HSQLDB example source code file (BundleHandler.java)

This example HSQLDB source code file (BundleHandler.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - HSQLDB tags/keywords

class, classloader, exception, exception, hashmap, hsqlarraylist, illegalargumentexception, locale, object, object, reflection, resourcebundle, resourcebundle, string, string, util

The HSQLDB BundleHandler.java source code

/* Copyright (c) 2001-2008, The HSQL Development Group
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of the HSQL Development Group nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL HSQL DEVELOPMENT GROUP, HSQLDB.ORG,
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */


package org.hsqldb.resources;

import java.lang.reflect.Method;
import java.util.Locale;
import java.util.MissingResourceException;
import java.util.ResourceBundle;

import org.hsqldb.lib.HashMap;
import org.hsqldb.lib.HsqlArrayList;

/**
 * A ResourceBundle helper class. <p>
 *
 * Allows clients to get/set locale and get at localized resource bundle
 * content in a resource path independent manner, without having to worry
 * about handling exception states or deal directly with ResourceBundle
 * object instances. Instead, clients recieve numeric handles to the
 * underlying objects.  Rather than causing exception states, missing or
 * inaccessible resources and underlying MissingResource and NullPointer
 * exceptions result in null return values when attempting to retrieve a
 * resource. <p>
 *
 * @author boucherb@users
 * @version 1.7.2
 * @since 1.7.2
 */
public final 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 object. */
    private static HashMap bundleHandleMap = new HashMap();

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

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

    /** 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 handle to the ResourceBundle
     * object corresponding to the specified name and current
     * <code>Locale, using the specified ClassLoader. 

     *
     * @return <code>int handle to the ResourceBundle
     *        object corresponding to the specified name and
     *        current <code>Locale, or -1 if no such bundle
     *        can be found
     * @param cl The ClassLoader to use in the search
     * @param name of the desired bundle
     */
    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 object corresponding
     * to the specified handle, the <code>String value corresponding
     * to the specified key.  <code>null is retrieved if either there
     *  is no <code>ResourceBundle object for the handle or there is no
     * <code>String value for the specified key. 

     *
     * @param handle an <code>int handle to a
     *      <code>ResourceBundle object
     * @param key A <code>String key to a String 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);
            }
        }
    }
}