maven-i18n-plugin/src/main/java/org/apache/myfaces/trinidadbuild/plugin/i18n/uixtools/LocaleDataResolver.java

/*
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
 *  with the License.  You may obtain a copy of the License at
 * 
 *  http://www.apache.org/licenses/LICENSE-2.0
 * 
 *  Unless required by applicable law or agreed to in writing,
 *  software distributed under the License is distributed on an
 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 *  KIND, either express or implied.  See the License for the
 *  specific language governing permissions and limitations
 *  under the License.
 */
package org.apache.myfaces.trinidadbuild.plugin.i18n.uixtools;

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

/**
 * Resolves locale specific elements like the names for month or date formats.
 * With Java 6 the needed resources are not stored anymore in reousrce files
 * but are hardcoded and can be accessed thru sun.util.resources.LocaleData.
 * <br>
 * This class uses reflection to access the resources to be compatible with
 * Java 1.4, 5 and 6.
 */
class LocaleDataResolver {

    private static final String LOCAL_ELEMENTS_RESOURCE_BUNDLE_JAVA_5 = "sun.text.resources.LocaleElements";

    private static final String LOCAL_DATA_CLASS_JAVA_4 = "sun.text.resources.LocaleData";

    private static final String LOCAL_DATA_CLASS_JAVA_6 = "sun.util.resources.LocaleData";

    private static final String[] LOCAL_DATA_METHODS_JAVA_6 = new String[] {
	    "getCalendarData", "getCollationData", "getCurrencyNames",
	    "getDateFormatData", "getLocaleNames", "getNumberFormatData",
	    "getTimeZoneNames" };

    private static final String DATE_TIME_ELEMENTS = "DateTimeElements";

    private static final String MINIMAL_DAYS_IN_FIRST_WEEK = "minimalDaysInFirstWeek";

    private static final String FIRST_DAY_OF_WEEK = "firstDayOfWeek";

    /**
     * Returns the element data for the given key and locale.
     *
     * @param key the key for the element
     * @param locale the locale to be used 
     * @return the locale dependent element
     */
    public static Object getElementData(String key, Locale locale) {
	try {
	    Class.forName(LOCAL_DATA_CLASS_JAVA_4);
	    return _getElementDataJava5(key, locale);
	} catch (ClassNotFoundException e) {
	    try {
		Class.forName(LOCAL_DATA_CLASS_JAVA_6);
		return _getElementDataJava6(key, locale);
	    } catch (ClassNotFoundException e1) {
		throw new IllegalStateException(
			"could not access the java resource bundles");
	    }
	}
    }

    /**
     * Returns the element data for the given key and locale using
     * the java 1.4/5 mechanism to access the resources.
     *
     * @param key the key for the element
     * @param locale the locale to be used 
     * @return the locale dependent element
     */
    private static Object _getElementDataJava5(String key, Locale locale) {
	ResourceBundle elementsData = ResourceBundle.getBundle(
		LOCAL_ELEMENTS_RESOURCE_BUNDLE_JAVA_5, locale);
	return elementsData.getObject(key);
    }

    /**
     * Returns the element data for the given key and locale using
     * the java 6 mechanism to access the resources.
     *
     * @param key the key for the element
     * @param locale the locale to be used 
     * @return the locale dependent element
     */
    private static Object _getElementDataJava6(String key, Locale locale) {

	if (DATE_TIME_ELEMENTS.equals(key)) {
	    return new Object[] {
		    _getElementDataJava6(FIRST_DAY_OF_WEEK, locale),
		    _getElementDataJava6(MINIMAL_DAYS_IN_FIRST_WEEK, locale) };
	} else {
	    for (int i = 0; i < LOCAL_DATA_METHODS_JAVA_6.length; i++) {
		ResourceBundle bundle = _getLocaleDataResourceBundleJava6(
			LOCAL_DATA_METHODS_JAVA_6[i], locale);
		if (_containsKey(bundle, key)) {
		    return bundle.getObject(key);
		}
	    }
	}

	throw new MissingResourceException(
		"no element found in the java resource bundles for the given key",
		null, key);
    }

    /**
     * @param bundle 
     * @param key 
     * @return true if the given key exists in the given bundle
     */
    private static boolean _containsKey(ResourceBundle bundle, String key) {
	for (Enumeration e = bundle.getKeys(); e.hasMoreElements();) {
	    if (((String) e.nextElement()).equals(key))
		return true;
	}
	return false;
    }

    /**
     * Gives access to the java 6 implementation using reflection.
     * 
     * @param name
     * @param locale
     * @return the resource bundle for the given method name and locale
     */
    private static ResourceBundle _getLocaleDataResourceBundleJava6(
	    String name, Locale locale) {
	try {
	    Class localDataClass = Class.forName(LOCAL_DATA_CLASS_JAVA_6);
	    Method method = localDataClass.getMethod(name,
		    new Class[] { Locale.class });
	    Object bundle = method.invoke(null, new Object[] { locale });
	    return (ResourceBundle) bundle;
	} catch (ClassNotFoundException e) {
	    throw new IllegalStateException();
	} catch (SecurityException e) {
	    throw new IllegalStateException();
	} catch (NoSuchMethodException e) {
	    throw new IllegalStateException();
	} catch (IllegalArgumentException e) {
	    throw new IllegalStateException();
	} catch (IllegalAccessException e) {
	    throw new IllegalStateException();
	} catch (InvocationTargetException e) {
	    throw new IllegalStateException();
	}
    }
}