getBundle. Now you can get your object by calling
* getObject or getString on that bundle.
*
* When a bundle is demanded for a specific locale, the ResourceBundle
* is searched in following order (def. language stands for the
* two letter ISO language code of the default locale (see
* Locale.getDefault()).
*
baseName_language code_country code_variant baseName_language code_country code baseName_language code baseName_def. language_def. country_def. variant baseName_def. language_def. country baseName_def. language baseName* *
A bundle is backed up by less specific bundles (omitting variant, country * or language). But it is not backed up by the default language locale. * *
If you provide a bundle for a given locale, say
* Bundle_en_UK_POSIX, you must also provide a bundle for
* all sub locales, ie. Bundle_en_UK, Bundle_en, and
* Bundle.
*
*
When a bundle is searched, we look first for a class with the given
* name, then for a file with .properties extension in the
* classpath. The name must be a fully qualified classname (with dots as
* path separators).
*
*
(Note: This implementation always backs up the class with a properties
* file if that is existing, but you shouldn't rely on this, if you want to
* be compatible to the standard JDK.)
*
* @author Jochen Hoenicke
* @author Eric Blake (ebb9@email.byu.edu)
* @see Locale
* @see ListResourceBundle
* @see PropertyResourceBundle
* @since 1.1
* @status updated to 1.4
*/
public abstract class ResourceBundle
{
/**
* Maximum size of our cache of ResourceBundles keyed by
* {@link BundleKey} instances.
*
* @see BundleKey
*/
private static final int CACHE_SIZE = 100;
/**
* The parent bundle. This is consulted when you call getObject and there
* is no such resource in the current bundle. This field may be null.
*/
protected ResourceBundle parent;
/**
* The locale of this resource bundle. You can read this with
* getLocale and it is automatically set in
* getBundle.
*/
private Locale locale;
/**
* A VM-wide cache of resource bundles already fetched.
*
* This {@link Map} is a Least Recently Used (LRU) cache, of the last
* {@link #CACHE_SIZE} accessed ResourceBundles keyed by the
* tuple: default locale, resource-bundle name, resource-bundle locale, and
* classloader.
*
* @see BundleKey
*/
private static Map bundleCache = new LinkedHashMap(CACHE_SIZE + 1, 0.75F, true)
{
public boolean removeEldestEntry(Map.Entry entry)
{
return size() > CACHE_SIZE;
}
};
/**
* The constructor. It does nothing special.
*/
public ResourceBundle()
{
}
/**
* Get a String from this resource bundle. Since most localized Objects
* are Strings, this method provides a convenient way to get them without
* casting.
*
* @param key the name of the resource
* @throws MissingResourceException if the resource can't be found
* @throws NullPointerException if key is null
* @throws ClassCastException if resource is not a string
*/
public final String getString(String key)
{
return (String) getObject(key);
}
/**
* Get an array of Strings from this resource bundle. This method
* provides a convenient way to get it without casting.
*
* @param key the name of the resource
* @throws MissingResourceException if the resource can't be found
* @throws NullPointerException if key is null
* @throws ClassCastException if resource is not a string
*/
public final String[] getStringArray(String key)
{
return (String[]) getObject(key);
}
/**
* Get an object from this resource bundle. This will call
* handleGetObject for this resource and all of its parents,
* until it finds a non-null resource.
*
* @param key the name of the resource
* @throws MissingResourceException if the resource can't be found
* @throws NullPointerException if key is null
*/
public final Object getObject(String key)
{
for (ResourceBundle bundle = this; bundle != null; bundle = bundle.parent)
{
Object o = bundle.handleGetObject(key);
if (o != null)
return o;
}
String className = getClass().getName();
throw new MissingResourceException("Key '" + key
+ "'not found in Bundle: "
+ className, className, key);
}
/**
* Return the actual locale of this bundle. You can use it after calling
* getBundle, to know if the bundle for the desired locale was loaded or
* if the fall back was used.
*
* @return the bundle's locale
*/
public Locale getLocale()
{
return locale;
}
/**
* Set the parent of this bundle. The parent is consulted when you call
* getObject and there is no such resource in the current bundle.
*
* @param parent the parent of this bundle
*/
protected void setParent(ResourceBundle parent)
{
this.parent = parent;
}
/**
* Get the appropriate ResourceBundle for the default locale. This is like
* calling getBundle(baseName, Locale.getDefault(),
* getClass().getClassLoader(), except that any security check of
* getClassLoader won't fail.
*
* @param baseName the name of the ResourceBundle
* @return the desired resource bundle
* @throws MissingResourceException if the resource bundle can't be found
* @throws NullPointerException if baseName is null
*/
public static ResourceBundle getBundle(String baseName)
{
ClassLoader cl = VMStackWalker.getCallingClassLoader();
if (cl == null)
cl = ClassLoader.getSystemClassLoader();
return getBundle(baseName, Locale.getDefault(), cl);
}
/**
* Get the appropriate ResourceBundle for the given locale. This is like
* calling getBundle(baseName, locale,
* getClass().getClassLoader(), except that any security check of
* getClassLoader won't fail.
*
* @param baseName the name of the ResourceBundle
* @param locale A locale
* @return the desired resource bundle
* @throws MissingResourceException if the resource bundle can't be found
* @throws NullPointerException if baseName or locale is null
*/
public static ResourceBundle getBundle(String baseName, Locale locale)
{
ClassLoader cl = VMStackWalker.getCallingClassLoader();
if (cl == null)
cl = ClassLoader.getSystemClassLoader();
return getBundle(baseName, locale, cl);
}
/** Cache key for the ResourceBundle cache. Resource bundles are keyed
by the combination of bundle name, locale, and class loader. */
private static class BundleKey
{
Locale defaultLocale;
String baseName;
Locale locale;
ClassLoader classLoader;
int hashcode;
BundleKey() {}
BundleKey(Locale dl, String s, Locale l, ClassLoader cl)
{
set(dl, s, l, cl);
}
void set(Locale dl, String s, Locale l, ClassLoader cl)
{
defaultLocale = dl;
baseName = s;
locale = l;
classLoader = cl;
hashcode = defaultLocale.hashCode() ^ baseName.hashCode()
^ locale.hashCode() ^ classLoader.hashCode();
}
public int hashCode()
{
return hashcode;
}
public boolean equals(Object o)
{
if (! (o instanceof BundleKey))
return false;
BundleKey key = (BundleKey) o;
return hashcode == key.hashcode
&& defaultLocale.equals(key.defaultLocale)
&& baseName.equals(key.baseName)
&& locale.equals(key.locale)
&& classLoader.equals(key.classLoader);
}
}
/** A cache lookup key. This avoids having to a new one for every
* getBundle() call. */
private static BundleKey lookupKey = new BundleKey();
/** Singleton cache entry to represent previous failed lookups. */
private static Object nullEntry = new Object();
/**
* Get the appropriate ResourceBundle for the given locale. The following
* strategy is used:
*
*
A sequence of candidate bundle names are generated, and tested in * this order, where the suffix 1 means the string from the specified * locale, and the suffix 2 means the string from the default locale:
* *In the sequence, entries with an empty string are ignored. Next,
* getBundle tries to instantiate the resource bundle:
Next, the parent chain is implemented. The remaining candidate names
* in the above sequence are tested in a similar manner, and if any results
* in a resource bundle, it is assigned as the parent of the first bundle
* using the setParent method (unless the first bundle already
* has a parent).
For example, suppose the following class and property files are * provided: MyResources.class, MyResources_fr_CH.properties, * MyResources_fr_CH.class, MyResources_fr.properties, * MyResources_en.properties, and MyResources_es_ES.class. The contents of * all files are valid (that is, public non-abstract subclasses of * ResourceBundle with public nullary constructors for the ".class" files, * syntactically correct ".properties" files). The default locale is * Locale("en", "UK").
* *Calling getBundle with the shown locale argument values instantiates * resource bundles from the following sources:
* *The file MyResources_fr_CH.properties is never used because it is hidden * by MyResources_fr_CH.class.
* * @param baseName the name of the ResourceBundle * @param locale A locale * @param classLoader a ClassLoader * @return the desired resource bundle * @throws MissingResourceException if the resource bundle can't be found * @throws NullPointerException if any argument is null * @since 1.2 */ // This method is synchronized so that the cache is properly // handled. public static synchronized ResourceBundle getBundle (String baseName, Locale locale, ClassLoader classLoader) { Locale defaultLocale = Locale.getDefault(); // This will throw NullPointerException if any arguments are null. lookupKey.set(defaultLocale, baseName, locale, classLoader); Object obj = bundleCache.get(lookupKey); if (obj instanceof ResourceBundle) return (ResourceBundle) obj; if (obj == nullEntry) throw new MissingResourceException("Bundle " + baseName + " not found for locale " + locale + " by classloader " + classLoader, baseName, ""); // First, look for a bundle for the specified locale. We don't want // the base bundle this time. boolean wantBase = locale.equals(defaultLocale); ResourceBundle bundle = tryBundle(baseName, locale, classLoader, wantBase); // Try the default locale if neccessary. if (bundle == null && ! wantBase) bundle = tryBundle(baseName, defaultLocale, classLoader, true); BundleKey key = new BundleKey(defaultLocale, baseName, locale, classLoader); if (bundle == null) { // Cache the fact that this lookup has previously failed. bundleCache.put(key, nullEntry); throw new MissingResourceException("Bundle " + baseName + " not found for locale " + locale + " by classloader " + classLoader, baseName, ""); } // Cache the result and return it. bundleCache.put(key, bundle); return bundle; } /** * Override this method to provide the resource for a keys. This gets * called bygetObject. If you don't have a resource
* for the given key, you should return null instead throwing a
* MissingResourceException. You don't have to ask the parent, getObject()
* already does this; nor should you throw a MissingResourceException.
*
* @param key the key of the resource
* @return the resource for the key, or null if not in bundle
* @throws NullPointerException if key is null
*/
protected abstract Object handleGetObject(String key);
/**
* This method should return all keys for which a resource exists; you
* should include the enumeration of any parent's keys, after filtering out
* duplicates.
*
* @return an enumeration of the keys
*/
public abstract Enumeration getKeys();
/**
* Tries to load a class or a property file with the specified name.
*
* @param localizedName the name
* @param classloader the classloader
* @return the resource bundle if it was loaded, otherwise the backup
*/
private static ResourceBundle tryBundle(String localizedName,
ClassLoader classloader)
{
ResourceBundle bundle = null;
try
{
Class rbClass;
if (classloader == null)
rbClass = Class.forName(localizedName);
else
rbClass = classloader.loadClass(localizedName);
// Note that we do the check up front instead of catching
// ClassCastException. The reason for this is that some crazy
// programs (Eclipse) have classes that do not extend
// ResourceBundle but that have the same name as a property
// bundle; in fact Eclipse relies on ResourceBundle not
// instantiating these classes.
if (ResourceBundle.class.isAssignableFrom(rbClass))
bundle = (ResourceBundle) rbClass.newInstance();
}
catch (Exception ex) {}
if (bundle == null)
{
try
{
InputStream is;
String resourceName
= localizedName.replace('.', '/') + ".properties";
if (classloader == null)
is = ClassLoader.getSystemResourceAsStream(resourceName);
else
is = classloader.getResourceAsStream(resourceName);
if (is != null)
bundle = new PropertyResourceBundle(is);
}
catch (IOException ex)
{
MissingResourceException mre = new MissingResourceException
("Failed to load bundle: " + localizedName, localizedName, "");
mre.initCause(ex);
throw mre;
}
}
return bundle;
}
/**
* Tries to load a the bundle for a given locale, also loads the backup
* locales with the same language.
*
* @param baseName the raw bundle name, without locale qualifiers
* @param locale the locale
* @param classLoader the classloader
* @param wantBase whether a resource bundle made only from the base name
* (with no locale information attached) should be returned.
* @return the resource bundle if it was loaded, otherwise the backup
*/
private static ResourceBundle tryBundle(String baseName, Locale locale,
ClassLoader classLoader,
boolean wantBase)
{
String language = locale.getLanguage();
String country = locale.getCountry();
String variant = locale.getVariant();
int baseLen = baseName.length();
// Build up a StringBuffer containing the complete bundle name, fully
// qualified by locale.
StringBuffer sb = new StringBuffer(baseLen + variant.length() + 7);
sb.append(baseName);
if (language.length() > 0)
{
sb.append('_');
sb.append(language);
if (country.length() > 0)
{
sb.append('_');
sb.append(country);
if (variant.length() > 0)
{
sb.append('_');
sb.append(variant);
}
}
}
// Now try to load bundles, starting with the most specialized name.
// Build up the parent chain as we go.
String bundleName = sb.toString();
ResourceBundle first = null; // The most specialized bundle.
ResourceBundle last = null; // The least specialized bundle.
while (true)
{
ResourceBundle foundBundle = tryBundle(bundleName, classLoader);
if (foundBundle != null)
{
if (first == null)
first = foundBundle;
if (last != null)
last.parent = foundBundle;
foundBundle.locale = locale;
last = foundBundle;
}
int idx = bundleName.lastIndexOf('_');
// Try the non-localized base name only if we already have a
// localized child bundle, or wantBase is true.
if (idx > baseLen || (idx == baseLen && (first != null || wantBase)))
bundleName = bundleName.substring(0, idx);
else
break;
}
return first;
}
}