resourcebundle.java

来自「This is a resource based on j2me embedde」· Java 代码 · 共 1,150 行 · 第 1/4 页

    /**
     * Remove any entries this thread may have in the construction list.
     * This is done as cleanup in the case where a bundle can't be
     * constructed.
     */
    private static void cleanUpConstructionList() {
        synchronized (cacheList) {
            final Collection entries = underConstruction.values();
            final Thread thisThread = Thread.currentThread();
            while (entries.remove(thisThread)) {
            }
        }
    }

    /**
     * Find a bundle in the cache or load it via the loader or a property file.
     * If the bundle isn't found, an entry is put in the constructionCache
     * and null is returned.  If null is returned, the caller must define the bundle
     * by calling putBundleInCache.  This routine also propagates NOT_FOUND values
     * from parent to child bundles when the parent is NOT_FOUND.
     * @param loader the loader to use when loading a bundle
     * @param bundleName the complete bundle name including locale extension
     * @param defaultLocale the default locale at the time getBundle was called
     * @param parent the parent of the resource bundle being loaded.  null if
     * the bundle is a root bundle
     * @return the bundle or null if the bundle could not be found in the cache
     * or loaded.
     */
    private static Object findBundle(ClassLoader loader, String bundleName, Locale defaultLocale,
            String baseName, Object parent) {
        Object result;
        synchronized (cacheList) {
            // Before we do the real work of this method, see
            // whether we need to do some housekeeping:
            // If references to class loaders have been nulled out,
            // remove all related information from the cache
            Reference ref = referenceQueue.poll();
            while (ref != null) {
                cacheList.remove(((LoaderReference) ref).getCacheKey());
                ref = referenceQueue.poll();
            }

            //check for bundle in cache
            cacheKey.setKeyValues(loader, bundleName, defaultLocale);
            result = cacheList.get(cacheKey);
            if (result != null) {
                cacheKey.clear();
                return result;
            }
            // check to see if some other thread is building this bundle.
            // Note that there is a rare chance that this thread is already
            // working on this bundle, and in the process getBundle was called
            // again, in which case we can't wait (4300693)
            Thread builder = (Thread) underConstruction.get(cacheKey);
            boolean beingBuilt = (builder != null && builder != Thread.currentThread());
            //if some other thread is building the bundle...
            if (beingBuilt) {
                //while some other thread is building the bundle...
                while (beingBuilt) {
                    cacheKey.clear();
                    try {
                        //Wait until the bundle is complete
                        cacheList.wait();
                    } catch (InterruptedException e) {
                    }
                    cacheKey.setKeyValues(loader, bundleName, defaultLocale);
                    beingBuilt = underConstruction.containsKey(cacheKey);
                }
                //if someone constructed the bundle for us, return it
                result = cacheList.get(cacheKey);
                if (result != null) {
                    cacheKey.clear();
                    return result;
                }
            }
            //The bundle isn't in the cache, so we are now responsible for
            //loading it and adding it to the cache.
            final Object key = cacheKey.clone();
            underConstruction.put(key, Thread.currentThread());
            //the bundle is removed from the cache by putBundleInCache
            cacheKey.clear();
        }

        //try loading the bundle via the class loader
        result = loadBundle(loader, bundleName, defaultLocale);
        if (result != null) {
            // check whether we're still responsible for construction -
            // a recursive call to getBundle might have handled it (4300693)
            boolean constructing;
            synchronized (cacheList) {
                cacheKey.setKeyValues(loader, bundleName, defaultLocale);
                constructing = underConstruction.get(cacheKey) == Thread.currentThread();
                cacheKey.clear();
            }
            if (constructing) {
                // set the bundle's parent and put it in the cache
                final ResourceBundle bundle = (ResourceBundle)result;
                if (parent != NOT_FOUND && bundle.parent == null) {
                    bundle.setParent((ResourceBundle) parent);
                }
                bundle.setLocale(baseName, bundleName);
                putBundleInCache(loader, bundleName, defaultLocale, result);
            }
        }
        return result;
    }

    /**
     * Calculate the bundles along the search path from the base bundle to the
     * bundle specified by baseName and locale.
     * @param baseName the base bundle name
     * @param locale the locale
     * @param names the vector used to return the names of the bundles along
     * the search path.
     *
     */
    private static Vector calculateBundleNames(String baseName, Locale locale) {
        final Vector result = new Vector(MAX_BUNDLES_SEARCHED);
        final String language = locale.getLanguage();
        final int languageLength = language.length();
        final String country = locale.getCountry();
        final int countryLength = country.length();
        final String variant = locale.getVariant();
        final int variantLength = variant.length();

        if (languageLength + countryLength + variantLength == 0) {
            //The locale is "", "", "".
            return result;
        }
        final StringBuffer temp = new StringBuffer(baseName);
        temp.append('_');
        temp.append(language);
        if (languageLength > 0) {
            result.addElement(temp.toString());
        }

        if (countryLength + variantLength == 0) {
            return result;
        }
        temp.append('_');
        temp.append(country);
        if (countryLength > 0) {
            result.addElement(temp.toString());
        }

        if (variantLength == 0) {
            return result;
        }
        temp.append('_');
        temp.append(variant);
        result.addElement(temp.toString());

        return result;
    }

    /**
     * Find a bundle in the cache.
     * @param loader the class loader that is responsible for loading the bundle.
     * @param bundleName the complete name of the bundle including locale extension.
     *      ex. sun.text.resources.LocaleElements_fr_BE
     * @param defaultLocale the default locale at the time getBundle was called
     * @return the cached bundle.  null if the bundle is not in the cache.
     */
    private static Object findBundleInCache(ClassLoader loader, String bundleName,
            Locale defaultLocale) {
        //Synchronize access to cacheList, cacheKey, and underConstruction
        synchronized (cacheList) {
            cacheKey.setKeyValues(loader, bundleName, defaultLocale);
            Object result = cacheList.get(cacheKey);
            cacheKey.clear();
            return result;
        }
    }

    /**
     * Put a new bundle in the cache and notify waiting threads that a new
     * bundle has been put in the cache.
     * @param defaultLocale the default locale at the time getBundle was called
     */
    private static void putBundleInCache(ClassLoader loader, String bundleName,
            Locale defaultLocale, Object value) {
        //we use a static shared cacheKey but we use the lock in cacheList since
        //the key is only used to interact with cacheList.
        synchronized (cacheList) {
            cacheKey.setKeyValues(loader, bundleName, defaultLocale);
            cacheList.put(cacheKey.clone(), value);
            underConstruction.remove(cacheKey);
            cacheKey.clear();
            //notify waiters that we're done constructing the bundle
            cacheList.notifyAll();
        }
    }

    /**
     * Load a bundle through either the specified ClassLoader or from a ".properties" file
     * and return the loaded bundle.
     * @param loader the ClassLoader to use to load the bundle.  If null, the system
     *      ClassLoader is used.
     * @param bundleName the name of the resource to load.  The name should be complete
     *      including a qualified class name followed by the locale extension.
     *      ex. sun.text.resources.LocaleElements_fr_BE
     * @param defaultLocale the default locale at the time getBundle was called
     * @return the bundle or null if none could be found.
     */
    private static Object loadBundle(final ClassLoader loader, String bundleName, Locale defaultLocale) {

	// replace any '/'s with '.'s for the bug-for-bug compatible
	// ClassLoader behavior. (5077272, see also 4872868)
	String correctedBundleName = bundleName.replace('/', '.');

        // Search for class file using class loader
        try {
            Class bundleClass;
            if (loader != null) {
                bundleClass = loader.loadClass(correctedBundleName);
            } else {
                bundleClass = Class.forName(correctedBundleName);
            }
            if (ResourceBundle.class.isAssignableFrom(bundleClass)) {
                Object myBundle = bundleClass.newInstance();
                // Creating the instance may have triggered a recursive call to getBundle,
                // in which case the bundle created by the recursive call would be in the
                // cache now (4300693). For consistency, we'd then return the bundle from the cache.
                Object otherBundle = findBundleInCache(loader, bundleName, defaultLocale);
                if (otherBundle != null) {
                    return otherBundle;
                } else {
                    return myBundle;
                }
            }
        } catch (Exception e) {
        } catch (LinkageError e) {
        }

        // Next search for a Properties file.
        final String resName = bundleName.replace('.', '/') + ".properties";
        InputStream stream = (InputStream)java.security.AccessController.doPrivileged(
            new java.security.PrivilegedAction() {
                public Object run() {
                    if (loader != null) {
                        return loader.getResourceAsStream(resName);
                    } else {
                        return ClassLoader.getSystemResourceAsStream(resName);
                    }
                }
            }
        );

        if (stream != null) {
            // make sure it is buffered
            stream = new java.io.BufferedInputStream(stream);
            try {
                return new PropertyResourceBundle(stream);
            } catch (Exception e) {
            } finally {
                try {
                    stream.close();
                } catch (Exception e) {
                    // to avoid propagating an IOException back into the caller
                    // (I'm assuming this is never going to happen, and if it does,
                    // I'm obeying the precedent of swallowing exceptions set by the
                    // existing code above)
                }
            }
        }
        return null;
    }

    /**
     * Gets an object for the given key from this resource bundle.
     * Returns null if this resource bundle does not contain an
     * object for the given key.
     *
     * @param key the key for the desired object
     * @exception NullPointerException if <code>key</code> is <code>null</code>
     * @return the object for the given key, or null
     */
    protected abstract Object handleGetObject(String key);

    /**
     * Returns an enumeration of the keys.
     *
     */
    public abstract Enumeration getKeys();
}