001/* ResourceBundle -- aids in loading resource bundles
002   Copyright (C) 1998, 1999, 2001, 2002, 2003, 2004, 2005, 2006
003   Free Software Foundation, Inc.
004
005This file is part of GNU Classpath.
006
007GNU Classpath is free software; you can redistribute it and/or modify
008it under the terms of the GNU General Public License as published by
009the Free Software Foundation; either version 2, or (at your option)
010any later version.
011
012GNU Classpath is distributed in the hope that it will be useful, but
013WITHOUT ANY WARRANTY; without even the implied warranty of
014MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
015General Public License for more details.
016
017You should have received a copy of the GNU General Public License
018along with GNU Classpath; see the file COPYING.  If not, write to the
019Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02002110-1301 USA.
021
022Linking this library statically or dynamically with other modules is
023making a combined work based on this library.  Thus, the terms and
024conditions of the GNU General Public License cover the whole
025combination.
026
027As a special exception, the copyright holders of this library give you
028permission to link this library with independent modules to produce an
029executable, regardless of the license terms of these independent
030modules, and to copy and distribute the resulting executable under
031terms of your choice, provided that you also meet, for each linked
032independent module, the terms and conditions of the license of that
033module.  An independent module is a module which is not derived from
034or based on this library.  If you modify this library, you may extend
035this exception to your version of the library, but you are not
036obligated to do so.  If you do not wish to do so, delete this
037exception statement from your version. */
038
039
040package java.util;
041
042import gnu.classpath.VMStackWalker;
043
044import gnu.java.lang.CPStringBuilder;
045
046import java.io.IOException;
047import java.io.InputStream;
048
049/**
050 * A resource bundle contains locale-specific data. If you need localized
051 * data, you can load a resource bundle that matches the locale with
052 * <code>getBundle</code>. Now you can get your object by calling
053 * <code>getObject</code> or <code>getString</code> on that bundle.
054 *
055 * <p>When a bundle is demanded for a specific locale, the ResourceBundle
056 * is searched in following order (<i>def. language</i> stands for the
057 * two letter ISO language code of the default locale (see
058 * <code>Locale.getDefault()</code>).
059 *
060<pre>baseName_<i>language code</i>_<i>country code</i>_<i>variant</i>
061baseName_<i>language code</i>_<i>country code</i>
062baseName_<i>language code</i>
063baseName_<i>def. language</i>_<i>def. country</i>_<i>def. variant</i>
064baseName_<i>def. language</i>_<i>def. country</i>
065baseName_<i>def. language</i>
066baseName</pre>
067 *
068 * <p>A bundle is backed up by less specific bundles (omitting variant, country
069 * or language). But it is not backed up by the default language locale.
070 *
071 * <p>If you provide a bundle for a given locale, say
072 * <code>Bundle_en_UK_POSIX</code>, you must also provide a bundle for
073 * all sub locales, ie. <code>Bundle_en_UK</code>, <code>Bundle_en</code>, and
074 * <code>Bundle</code>.
075 *
076 * <p>When a bundle is searched, we look first for a class with the given
077 * name, then for a file with <code>.properties</code> extension in the
078 * classpath. The name must be a fully qualified classname (with dots as
079 * path separators).
080 *
081 * <p>(Note: This implementation always backs up the class with a properties
082 * file if that is existing, but you shouldn't rely on this, if you want to
083 * be compatible to the standard JDK.)
084 *
085 * @author Jochen Hoenicke
086 * @author Eric Blake (ebb9@email.byu.edu)
087 * @see Locale
088 * @see ListResourceBundle
089 * @see PropertyResourceBundle
090 * @since 1.1
091 * @status updated to 1.4
092 */
093public abstract class ResourceBundle
094{
095  /**
096   * Maximum size of our cache of <code>ResourceBundle</code>s keyed by
097   * {@link BundleKey} instances.
098   *
099   * @see BundleKey
100   */
101  private static final int CACHE_SIZE = 100;
102
103  /**
104   * The parent bundle. This is consulted when you call getObject and there
105   * is no such resource in the current bundle. This field may be null.
106   */
107  protected ResourceBundle parent;
108
109  /**
110   * The locale of this resource bundle. You can read this with
111   * <code>getLocale</code> and it is automatically set in
112   * <code>getBundle</code>.
113   */
114  private Locale locale;
115
116  /**
117   * A VM-wide cache of resource bundles already fetched.
118   * <p>
119   * This {@link Map} is a Least Recently Used (LRU) cache, of the last
120   * {@link #CACHE_SIZE} accessed <code>ResourceBundle</code>s keyed by the
121   * tuple: default locale, resource-bundle name, resource-bundle locale, and
122   * classloader.
123   *
124   * @see BundleKey
125   */
126  private static Map<BundleKey,Object> bundleCache =
127    new LinkedHashMap<BundleKey,Object>(CACHE_SIZE + 1, 0.75F, true)
128  {
129    public boolean removeEldestEntry(Map.Entry<BundleKey,Object> entry)
130    {
131      return size() > CACHE_SIZE;
132    }
133  };
134
135  /**
136   * The constructor. It does nothing special.
137   */
138  public ResourceBundle()
139  {
140  }
141
142  /**
143   * Get a String from this resource bundle. Since most localized Objects
144   * are Strings, this method provides a convenient way to get them without
145   * casting.
146   *
147   * @param key the name of the resource
148   * @throws MissingResourceException if the resource can't be found
149   * @throws NullPointerException if key is null
150   * @throws ClassCastException if resource is not a string
151   */
152  public final String getString(String key)
153  {
154    return (String) getObject(key);
155  }
156
157  /**
158   * Get an array of Strings from this resource bundle. This method
159   * provides a convenient way to get it without casting.
160   *
161   * @param key the name of the resource
162   * @throws MissingResourceException if the resource can't be found
163   * @throws NullPointerException if key is null
164   * @throws ClassCastException if resource is not a string
165   */
166  public final String[] getStringArray(String key)
167  {
168    return (String[]) getObject(key);
169  }
170
171  /**
172   * Get an object from this resource bundle. This will call
173   * <code>handleGetObject</code> for this resource and all of its parents,
174   * until it finds a non-null resource.
175   *
176   * @param key the name of the resource
177   * @throws MissingResourceException if the resource can't be found
178   * @throws NullPointerException if key is null
179   */
180  public final Object getObject(String key)
181  {
182    for (ResourceBundle bundle = this; bundle != null; bundle = bundle.parent)
183      {
184        Object o = bundle.handleGetObject(key);
185        if (o != null)
186          return o;
187      }
188
189    String className = getClass().getName();
190    throw new MissingResourceException("Key '" + key
191                                       + "'not found in Bundle: "
192                                       + className, className, key);
193  }
194
195  /**
196   * Return the actual locale of this bundle. You can use it after calling
197   * getBundle, to know if the bundle for the desired locale was loaded or
198   * if the fall back was used.
199   *
200   * @return the bundle's locale
201   */
202  public Locale getLocale()
203  {
204    return locale;
205  }
206
207  /**
208   * Set the parent of this bundle. The parent is consulted when you call
209   * getObject and there is no such resource in the current bundle.
210   *
211   * @param parent the parent of this bundle
212   */
213  protected void setParent(ResourceBundle parent)
214  {
215    this.parent = parent;
216  }
217
218  /**
219   * Get the appropriate ResourceBundle for the default locale. This is like
220   * calling <code>getBundle(baseName, Locale.getDefault(),
221   * getClass().getClassLoader()</code>, except that any security check of
222   * getClassLoader won't fail.
223   *
224   * @param baseName the name of the ResourceBundle
225   * @return the desired resource bundle
226   * @throws MissingResourceException if the resource bundle can't be found
227   * @throws NullPointerException if baseName is null
228   */
229  public static ResourceBundle getBundle(String baseName)
230  {
231    ClassLoader cl = VMStackWalker.getCallingClassLoader();
232    if (cl == null)
233      cl = ClassLoader.getSystemClassLoader();
234    return getBundle(baseName, Locale.getDefault(), cl);
235  }
236
237  /**
238   * Get the appropriate ResourceBundle for the given locale. This is like
239   * calling <code>getBundle(baseName, locale,
240   * getClass().getClassLoader()</code>, except that any security check of
241   * getClassLoader won't fail.
242   *
243   * @param baseName the name of the ResourceBundle
244   * @param locale A locale
245   * @return the desired resource bundle
246   * @throws MissingResourceException if the resource bundle can't be found
247   * @throws NullPointerException if baseName or locale is null
248   */
249  public static ResourceBundle getBundle(String baseName, Locale locale)
250  {
251    ClassLoader cl = VMStackWalker.getCallingClassLoader();
252    if (cl == null)
253      cl = ClassLoader.getSystemClassLoader();
254    return getBundle(baseName, locale, cl);
255  }
256
257  /** Cache key for the ResourceBundle cache.  Resource bundles are keyed
258      by the combination of bundle name, locale, and class loader. */
259  private static class BundleKey
260  {
261    Locale defaultLocale;
262    String baseName;
263    Locale locale;
264    ClassLoader classLoader;
265    int hashcode;
266
267    BundleKey() {}
268
269    BundleKey(Locale dl, String s, Locale l, ClassLoader cl)
270    {
271      set(dl, s, l, cl);
272    }
273
274    void set(Locale dl, String s, Locale l, ClassLoader cl)
275    {
276      defaultLocale = dl;
277      baseName = s;
278      locale = l;
279      classLoader = cl;
280      hashcode = defaultLocale.hashCode() ^ baseName.hashCode()
281          ^ locale.hashCode() ^ classLoader.hashCode();
282    }
283
284    public int hashCode()
285    {
286      return hashcode;
287    }
288
289    public boolean equals(Object o)
290    {
291      if (! (o instanceof BundleKey))
292        return false;
293      BundleKey key = (BundleKey) o;
294      return hashcode == key.hashcode
295          && defaultLocale.equals(key.defaultLocale)
296          && baseName.equals(key.baseName)
297          && locale.equals(key.locale)
298          && classLoader.equals(key.classLoader);
299    }
300
301    public String toString()
302    {
303      CPStringBuilder builder = new CPStringBuilder(getClass().getName());
304      builder.append("[defaultLocale=");
305      builder.append(defaultLocale);
306      builder.append(",baseName=");
307      builder.append(baseName);
308      builder.append(",locale=");
309      builder.append(locale);
310      builder.append(",classLoader=");
311      builder.append(classLoader);
312      builder.append("]");
313      return builder.toString();
314    }
315  }
316
317  /** A cache lookup key. This avoids having to a new one for every
318   *  getBundle() call. */
319  private static final BundleKey lookupKey = new BundleKey();
320
321  /** Singleton cache entry to represent previous failed lookups. */
322  private static final Object nullEntry = new Object();
323
324  /**
325   * Get the appropriate ResourceBundle for the given locale. The following
326   * strategy is used:
327   *
328   * <p>A sequence of candidate bundle names are generated, and tested in
329   * this order, where the suffix 1 means the string from the specified
330   * locale, and the suffix 2 means the string from the default locale:</p>
331   *
332   * <ul>
333   * <li>baseName + "_" + language1 + "_" + country1 + "_" + variant1</li>
334   * <li>baseName + "_" + language1 + "_" + country1</li>
335   * <li>baseName + "_" + language1</li>
336   * <li>baseName + "_" + language2 + "_" + country2 + "_" + variant2</li>
337   * <li>baseName + "_" + language2 + "_" + country2</li>
338   * <li>baseName + "_" + language2</li>
339   * <li>baseName</li>
340   * </ul>
341   *
342   * <p>In the sequence, entries with an empty string are ignored. Next,
343   * <code>getBundle</code> tries to instantiate the resource bundle:</p>
344   *
345   * <ul>
346   * <li>First, an attempt is made to load a class in the specified classloader
347   * which is a subclass of ResourceBundle, and which has a public constructor
348   * with no arguments, via reflection.</li>
349   * <li>Next, a search is made for a property resource file, by replacing
350   * '.' with '/' and appending ".properties", and using
351   * ClassLoader.getResource(). If a file is found, then a
352   * PropertyResourceBundle is created from the file's contents.</li>
353   * </ul>
354   * If no resource bundle was found, a MissingResourceException is thrown.
355   *
356   * <p>Next, the parent chain is implemented. The remaining candidate names
357   * in the above sequence are tested in a similar manner, and if any results
358   * in a resource bundle, it is assigned as the parent of the first bundle
359   * using the <code>setParent</code> method (unless the first bundle already
360   * has a parent).</p>
361   *
362   * <p>For example, suppose the following class and property files are
363   * provided: MyResources.class, MyResources_fr_CH.properties,
364   * MyResources_fr_CH.class, MyResources_fr.properties,
365   * MyResources_en.properties, and MyResources_es_ES.class. The contents of
366   * all files are valid (that is, public non-abstract subclasses of
367   * ResourceBundle with public nullary constructors for the ".class" files,
368   * syntactically correct ".properties" files). The default locale is
369   * Locale("en", "UK").</p>
370   *
371   * <p>Calling getBundle with the shown locale argument values instantiates
372   * resource bundles from the following sources:</p>
373   *
374   * <ul>
375   * <li>Locale("fr", "CH"): result MyResources_fr_CH.class, parent
376   *   MyResources_fr.properties, parent MyResources.class</li>
377   * <li>Locale("fr", "FR"): result MyResources_fr.properties, parent
378   *   MyResources.class</li>
379   * <li>Locale("de", "DE"): result MyResources_en.properties, parent
380   *   MyResources.class</li>
381   * <li>Locale("en", "US"): result MyResources_en.properties, parent
382   *   MyResources.class</li>
383   * <li>Locale("es", "ES"): result MyResources_es_ES.class, parent
384   *   MyResources.class</li>
385   * </ul>
386   *
387   * <p>The file MyResources_fr_CH.properties is never used because it is hidden
388   * by MyResources_fr_CH.class.</p>
389   *
390   * @param baseName the name of the ResourceBundle
391   * @param locale A locale
392   * @param classLoader a ClassLoader
393   * @return the desired resource bundle
394   * @throws MissingResourceException if the resource bundle can't be found
395   * @throws NullPointerException if any argument is null
396   * @since 1.2
397   */
398  // This method is synchronized so that the cache is properly
399  // handled.
400  public static synchronized ResourceBundle getBundle
401    (String baseName, Locale locale, ClassLoader classLoader)
402  {
403    Locale defaultLocale = Locale.getDefault();
404    // This will throw NullPointerException if any arguments are null.
405    lookupKey.set(defaultLocale, baseName, locale, classLoader);
406    Object obj = bundleCache.get(lookupKey);
407    if (obj instanceof ResourceBundle)
408      return (ResourceBundle) obj;
409
410    if (obj == nullEntry)
411      throw new MissingResourceException("Bundle " + baseName
412                                         + " not found for locale " + locale
413                                         + " by classloader " + classLoader,
414                                         baseName, "");
415    // First, look for a bundle for the specified locale. We don't want
416    // the base bundle this time.
417    boolean wantBase = locale.equals(defaultLocale);
418    ResourceBundle bundle = tryBundle(baseName, locale, classLoader, wantBase);
419    // Try the default locale if neccessary.
420    if (bundle == null && ! wantBase)
421      bundle = tryBundle(baseName, defaultLocale, classLoader, true);
422
423    BundleKey key = new BundleKey(defaultLocale, baseName, locale, classLoader);
424    if (bundle == null)
425      {
426        // Cache the fact that this lookup has previously failed.
427        bundleCache.put(key, nullEntry);
428        throw new MissingResourceException("Bundle " + baseName
429                                           + " not found for locale " + locale
430                                           + " by classloader " + classLoader,
431                                           baseName, "");
432      }
433    // Cache the result and return it.
434    bundleCache.put(key, bundle);
435    return bundle;
436  }
437
438  /**
439   * Override this method to provide the resource for a keys. This gets
440   * called by <code>getObject</code>. If you don't have a resource
441   * for the given key, you should return null instead throwing a
442   * MissingResourceException. You don't have to ask the parent, getObject()
443   * already does this; nor should you throw a MissingResourceException.
444   *
445   * @param key the key of the resource
446   * @return the resource for the key, or null if not in bundle
447   * @throws NullPointerException if key is null
448   */
449  protected abstract Object handleGetObject(String key);
450
451  /**
452   * This method should return all keys for which a resource exists; you
453   * should include the enumeration of any parent's keys, after filtering out
454   * duplicates.
455   *
456   * @return an enumeration of the keys
457   */
458  public abstract Enumeration<String> getKeys();
459
460  /**
461   * Tries to load a class or a property file with the specified name.
462   *
463   * @param localizedName the name
464   * @param classloader the classloader
465   * @return the resource bundle if it was loaded, otherwise the backup
466   */
467  private static ResourceBundle tryBundle(String localizedName,
468                                          ClassLoader classloader)
469  {
470    ResourceBundle bundle = null;
471    try
472      {
473        Class<?> rbClass;
474        if (classloader == null)
475          rbClass = Class.forName(localizedName);
476        else
477          rbClass = classloader.loadClass(localizedName);
478        // Note that we do the check up front instead of catching
479        // ClassCastException.  The reason for this is that some crazy
480        // programs (Eclipse) have classes that do not extend
481        // ResourceBundle but that have the same name as a property
482        // bundle; in fact Eclipse relies on ResourceBundle not
483        // instantiating these classes.
484        if (ResourceBundle.class.isAssignableFrom(rbClass))
485          bundle = (ResourceBundle) rbClass.newInstance();
486      }
487    catch (Exception ex) {}
488
489    if (bundle == null)
490      {
491        try
492          {
493            InputStream is;
494            String resourceName
495              = localizedName.replace('.', '/') + ".properties";
496            if (classloader == null)
497              is = ClassLoader.getSystemResourceAsStream(resourceName);
498            else
499              is = classloader.getResourceAsStream(resourceName);
500            if (is != null)
501              bundle = new PropertyResourceBundle(is);
502          }
503        catch (IOException ex)
504          {
505            MissingResourceException mre = new MissingResourceException
506              ("Failed to load bundle: " + localizedName, localizedName, "");
507            mre.initCause(ex);
508            throw mre;
509          }
510      }
511
512    return bundle;
513  }
514
515  /**
516   * Tries to load the bundle for a given locale, also loads the backup
517   * locales with the same language.
518   *
519   * @param baseName the raw bundle name, without locale qualifiers
520   * @param locale the locale
521   * @param classLoader the classloader
522   * @param wantBase whether a resource bundle made only from the base name
523   *        (with no locale information attached) should be returned.
524   * @return the resource bundle if it was loaded, otherwise the backup
525   */
526  private static ResourceBundle tryBundle(String baseName, Locale locale,
527                                          ClassLoader classLoader,
528                                          boolean wantBase)
529  {
530    String language = locale.getLanguage();
531    String country = locale.getCountry();
532    String variant = locale.getVariant();
533
534    int baseLen = baseName.length();
535
536    // Build up a CPStringBuilder containing the complete bundle name, fully
537    // qualified by locale.
538    CPStringBuilder sb = new CPStringBuilder(baseLen + variant.length() + 7);
539
540    sb.append(baseName);
541
542    if (language.length() > 0)
543      {
544        sb.append('_');
545        sb.append(language);
546
547        if (country.length() > 0)
548          {
549            sb.append('_');
550            sb.append(country);
551
552            if (variant.length() > 0)
553              {
554                sb.append('_');
555                sb.append(variant);
556              }
557          }
558      }
559
560    // Now try to load bundles, starting with the most specialized name.
561    // Build up the parent chain as we go.
562    String bundleName = sb.toString();
563    ResourceBundle first = null; // The most specialized bundle.
564    ResourceBundle last = null; // The least specialized bundle.
565
566    while (true)
567      {
568        ResourceBundle foundBundle = tryBundle(bundleName, classLoader);
569        if (foundBundle != null)
570          {
571            if (first == null)
572              first = foundBundle;
573            if (last != null)
574              last.parent = foundBundle;
575            foundBundle.locale = locale;
576            last = foundBundle;
577          }
578        int idx = bundleName.lastIndexOf('_');
579        // Try the non-localized base name only if we already have a
580        // localized child bundle, or wantBase is true.
581        if (idx > baseLen || (idx == baseLen && (first != null || wantBase)))
582          bundleName = bundleName.substring(0, idx);
583        else
584          break;
585      }
586
587    return first;
588  }
589
590  /**
591   * Remove all resources from the cache that were loaded
592   * using the class loader of the calling class.
593   *
594   * @since 1.6
595   */
596  public static final void clearCache()
597  {
598    clearCache(VMStackWalker.getCallingClassLoader());
599  }
600
601  /**
602   * Remove all resources from the cache that were loaded
603   * using the specified class loader.
604   *
605   * @param loader the loader used for the bundles that will be removed.
606   * @throws NullPointerException if {@code loader} is {@code null}.
607   * @since 1.6
608   */
609  public static final void clearCache(ClassLoader loader)
610  {
611    if (loader == null)
612      throw new NullPointerException("The loader can not be null.");
613    synchronized (ResourceBundle.class)
614      {
615        Iterator<BundleKey> iter = bundleCache.keySet().iterator();
616        while (iter.hasNext())
617          {
618            BundleKey key = iter.next();
619            if (key.classLoader == loader)
620              iter.remove();
621          }
622      }
623  }
624
625}