resourcebundle.java

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

    /**
     * Gets a resource bundle using the specified base name and locale,
     * and the caller's class loader. Calling this method is equivalent to calling
     * <blockquote>
     * <code>getBundle(baseName, locale, this.getClass().getClassLoader())</code>,
     * </blockquote>
     * except that <code>getClassLoader()</code> is run with the security
     * privileges of <code>ResourceBundle</code>.
     * See {@link #getBundle(java.lang.String, java.util.Locale, java.lang.ClassLoader) getBundle}
     * for a complete description of the search and instantiation strategy.
     *
     * @param baseName the base name of the resource bundle, a fully qualified class name
     * @param locale the locale for which a resource bundle is desired
     * @exception java.lang.NullPointerException
     *     if <code>baseName</code> or <code>locale</code> is <code>null</code>
     * @exception MissingResourceException
     *     if no resource bundle for the specified base name can be found
     * @return a resource bundle for the given base name and locale
     */
    public static final ResourceBundle getBundle(String baseName,
                                                         Locale locale)
    {
        return getBundleImpl(baseName, locale, getLoader());
    }

    /**
     * Gets a resource bundle using the specified base name, locale, and class loader.
     *
     * <p>
     * Conceptually, <code>getBundle</code> uses the following strategy for locating and instantiating
     * resource bundles:
     * <p>
     * <code>getBundle</code> uses the base name, the specified locale, and the default
     * locale (obtained from {@link java.util.Locale#getDefault() Locale.getDefault})
     * to generate a sequence of <em>candidate bundle names</em>.
     * If the specified locale's language, country, and variant are all empty
     * strings, then the base name is the only candidate bundle name.
     * Otherwise, the following sequence is generated from the attribute
     * values of the specified locale (language1, country1, and variant1)
     * and of the default locale (language2, country2, and variant2):
     * <ul>
     * <li> baseName + "_" + language1 + "_" + country1 + "_" + variant1
     * <li> baseName + "_" + language1 + "_" + country1
     * <li> baseName + "_" + language1
     * <li> baseName + "_" + language2 + "_" + country2 + "_" + variant2
     * <li> baseName + "_" + language2 + "_" + country2
     * <li> baseName + "_" + language2
     * <li> baseName
     * </ul>
     * <p>
     * Candidate bundle names where the final component is an empty string are omitted.
     * For example, if country1 is an empty string, the second candidate bundle name is omitted.
     *
     * <p>
     * <code>getBundle</code> then iterates over the candidate bundle names to find the first
     * one for which it can <em>instantiate</em> an actual resource bundle. For each candidate
     * bundle name, it attempts to create a resource bundle:
     * <ul>
     * <li>
     * First, it attempts to load a class using the candidate bundle name.
     * If such a class can be found and loaded using the specified class loader, is assignment
     * compatible with ResourceBundle, is accessible from ResourceBundle, and can be instantiated,
     * <code>getBundle</code> creates a new instance of this class and uses it as the <em>result
     * resource bundle</em>.
     * <li>
     * Otherwise, <code>getBundle</code> attempts to locate a property resource file.
     * It generates a path name from the candidate bundle name by replacing all "." characters
     * with "/" and appending the string ".properties".
     * It attempts to find a "resource" with this name using
     * {@link java.lang.ClassLoader#getResource(java.lang.String) ClassLoader.getResource}.
     * (Note that a "resource" in the sense of <code>getResource</code> has nothing to do with
     * the contents of a resource bundle, it is just a container of data, such as a file.)
     * If it finds a "resource", it attempts to create a new
     * {@link PropertyResourceBundle} instance from its contents.
     * If successful, this instance becomes the <em>result resource bundle</em>.
     * </ul>
     *
     * <p>
     * If no result resource bundle has been found, a <code>MissingResourceException</code>
     * is thrown.
     *
     * <p>
     * Once a result resource bundle has been found, its parent chain is instantiated.
     * <code>getBundle</code> iterates over the candidate bundle names that can be
     * obtained by successively removing variant, country, and language
     * (each time with the preceding "_") from the bundle name of the result resource bundle.
     * As above, candidate bundle names where the final component is an empty string are omitted.
     * With each of the candidate bundle names it attempts to instantiate a resource bundle, as
     * described above.
     * Whenever it succeeds, it calls the previously instantiated resource
     * bundle's {@link #setParent(java.util.ResourceBundle) setParent} method
     * with the new resource bundle, unless the previously instantiated resource
     * bundle already has a non-null parent.
     *
     * <p>
     * Implementations of <code>getBundle</code> may cache instantiated resource bundles
     * and return the same resource bundle instance multiple times. They may also
     * vary the sequence in which resource bundles are instantiated as long as the
     * selection of the result resource bundle and its parent chain are compatible with
     * the description above.
     *
     * <p>
     * The <code>baseName</code> argument should be a fully qualified class name. However, for
     * compatibility with earlier versions, Sun's Java 2 runtime environments do not verify this,
     * and so it is possible to access <code>PropertyResourceBundle</code>s by specifying a
     * path name (using "/") instead of a fully qualified class name (using ".").
     *
     * <p>
     * <strong>Example:</strong> The following class and property files are provided:
     * MyResources.class, MyResources_fr_CH.properties, MyResources_fr_CH.class,
     * MyResources_fr.properties, MyResources_en.properties, MyResources_es_ES.class.
     * The contents of all files are valid (that is, public non-abstract subclasses of ResourceBundle for
     * the ".class" files, syntactically correct ".properties" files).
     * The default locale is <code>Locale("en", "GB")</code>.
     * <p>
     * Calling <code>getBundle</code> with the shown locale argument values instantiates
     * resource bundles from the following sources:
     * <ul>
     * <li>Locale("fr", "CH"): result MyResources_fr_CH.class, parent MyResources_fr.properties, parent MyResources.class
     * <li>Locale("fr", "FR"): result MyResources_fr.properties, parent MyResources.class
     * <li>Locale("de", "DE"): result MyResources_en.properties, parent MyResources.class
     * <li>Locale("en", "US"): result MyResources_en.properties, parent MyResources.class
     * <li>Locale("es", "ES"): result MyResources_es_ES.class, parent MyResources.class
     * </ul>
     * The file MyResources_fr_CH.properties is never used because it is hidden by
     * MyResources_fr_CH.class.
     *
     * <p>
     *
     * @param baseName the base name of the resource bundle, a fully qualified class name
     * @param locale the locale for which a resource bundle is desired
     * @param loader the class loader from which to load the resource bundle
     * @exception java.lang.NullPointerException
     *     if <code>baseName</code>, <code>locale</code>, or <code>loader</code> is <code>null</code>
     * @exception MissingResourceException
     *     if no resource bundle for the specified base name can be found
     * @return a resource bundle for the given base name and locale
     * @since 1.2
     */
    public static ResourceBundle getBundle(String baseName, Locale locale,
                                           ClassLoader loader)
    {
        if (loader == null) {
            throw new NullPointerException();
        }
        return getBundleImpl(baseName, locale, loader);
    }

    private static ResourceBundle getBundleImpl(String baseName, Locale locale,
                                           ClassLoader loader)
    {
        if (baseName == null) {
            throw new NullPointerException();
        }

        //fast path the case where the bundle is cached
        String bundleName = baseName;
        String localeSuffix = locale.toString();
        if (localeSuffix.length() > 0) {
            bundleName += "_" + localeSuffix;
        } else if (locale.getVariant().length() > 0) {
            //This corrects some strange behavior in Locale where
            //new Locale("", "", "VARIANT").toString == ""
            bundleName += "___" + locale.getVariant();
        }
        
        // The default locale may influence the lookup result, and
        // it may change, so we get it here once.
        Locale defaultLocale = Locale.getDefault();

        Object lookup = findBundleInCache(loader, bundleName, defaultLocale);
        if (lookup == NOT_FOUND) {
            throwMissingResourceException(baseName, locale);
        } else if (lookup != null) {
            return (ResourceBundle)lookup;
        }

        //The bundle was not cached, so start doing lookup at the root
        //Resources are loaded starting at the root and working toward
        //the requested bundle.

        //If findBundle returns null, we become responsible for defining
        //the bundle, and must call putBundleInCache to complete this
        //task.  This is critical because other threads may be waiting
        //for us to finish.

        Object parent = NOT_FOUND;
        try {
            //locate the root bundle and work toward the desired child
            Object root = findBundle(loader, baseName, defaultLocale, baseName, null);
            if (root == null) {
                putBundleInCache(loader, baseName, defaultLocale, NOT_FOUND);
                root = NOT_FOUND;
            }

            // Search the main branch of the search tree.
            // We need to keep references to the bundles we find on the main path
            // so they don't get garbage collected before we get to propagate().
            final Vector names = calculateBundleNames(baseName, locale);
            Vector bundlesFound = new Vector(MAX_BUNDLES_SEARCHED);
	    // if we found the root bundle and no other bundle names are needed
	    // we can stop here. We don't need to search or load anything further.
            boolean foundInMainBranch = (root != NOT_FOUND && names.size() == 0);
	    
	    if (!foundInMainBranch) {
	      parent = root;
	      for (int i = 0; i < names.size(); i++) {
                bundleName = (String)names.elementAt(i);
                lookup = findBundle(loader, bundleName, defaultLocale, baseName, parent);
                bundlesFound.addElement(lookup);
                if (lookup != null) {
                    parent = lookup;
                    foundInMainBranch = true;
                }
	      }
            }
            parent = root;
            if (!foundInMainBranch) {
                //we didn't find anything on the main branch, so we do the fallback branch
                final Vector fallbackNames = calculateBundleNames(baseName, defaultLocale);
                for (int i = 0; i < fallbackNames.size(); i++) {
                    bundleName = (String)fallbackNames.elementAt(i);
                    if (names.contains(bundleName)) {
                        //the fallback branch intersects the main branch so we can stop now.
                        break;
                    }
                    lookup = findBundle(loader, bundleName, defaultLocale, baseName, parent);
                    if (lookup != null) {
                        parent = lookup;
                    } else {
                        //propagate the parent to the child.  We can do this
                        //here because we are in the default path.
                        putBundleInCache(loader, bundleName, defaultLocale, parent);
                    }
                }
            }
            //propagate the inheritance/fallback down through the main branch
            parent = propagate(loader, names, bundlesFound, defaultLocale, parent);
        } catch (Exception e) {
            //We should never get here unless there has been a change
            //to the code that doesn't catch it's own exceptions.
            cleanUpConstructionList();
            throwMissingResourceException(baseName, locale);
        } catch (Error e) {
            //The only Error that can currently hit this code is a ThreadDeathError
            //but errors might be added in the future, so we'll play it safe and
            //clean up.
            cleanUpConstructionList();
            throw e;
        }
        if (parent == NOT_FOUND) {
            throwMissingResourceException(baseName, locale);
        }
        return (ResourceBundle)parent;
    }

    /**
     * propagate bundles from the root down the specified branch of the search tree.
     * @param loader the class loader for the bundles
     * @param names the names of the bundles along search path
     * @param bundlesFound the bundles corresponding to the names (some may be null)
     * @param defaultLocale the default locale at the time getBundle was called
     * @param parent the parent of the first bundle in the path (the root bundle)
     * @return the value of the last bundle along the path
     */
    private static Object propagate(ClassLoader loader, Vector names,
            Vector bundlesFound, Locale defaultLocale, Object parent) {
        for (int i = 0; i < names.size(); i++) {
            final String bundleName = (String)names.elementAt(i);
            final Object lookup = bundlesFound.elementAt(i);
            if (lookup == null) {
                putBundleInCache(loader, bundleName, defaultLocale, parent);
            } else {
                parent = lookup;
            }
        }
        return parent;
    }

    /** Throw a MissingResourceException with proper message */
    private static void throwMissingResourceException(String baseName, Locale locale)
            throws MissingResourceException{
        throw new MissingResourceException("Can't find bundle for base name "
                                           + baseName + ", locale " + locale,
                                           baseName + "_" + locale,"");
    }