Java tutorial
/* * Copyright (C) 2010, Sasa Zivkov <sasa.zivkov@sap.com> * and other copyright owners as documented in the project's IP log. * * This program and the accompanying materials are made available * under the terms of the Eclipse Distribution License v1.0 which * accompanies this distribution, is reproduced below, and is * available at http://www.eclipse.org/org/documents/edl-v10.php * * All rights reserved. * * Redistribution and use in source and binary forms, with or * without modification, are permitted provided that the following * conditions are met: * * - Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * - Redistributions in binary form must reproduce the above * copyright notice, this list of conditions and the following * disclaimer in the documentation and/or other materials provided * with the distribution. * * - Neither the name of the Eclipse Foundation, Inc. nor the * names of its contributors may be used to endorse or promote * products derived from this software without specific prior * written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ package org.eclipse.jgit.nls; import java.lang.reflect.Field; import java.util.Locale; import java.util.MissingResourceException; import java.util.ResourceBundle; import org.eclipse.jgit.errors.TranslationBundleLoadingException; import org.eclipse.jgit.errors.TranslationStringMissingException; /** * Base class for all translation bundles that provides injection of translated * texts into public String fields. * * <p> * The usage pattern is shown with the following example. First define a new * translation bundle: * * <pre> * public class TransportText extends TranslationBundle { * public static TransportText get() { * return NLS.getBundleFor(TransportText.class); * } * * public String repositoryNotFound; * * public String transportError; * } * </pre> * * Second, define one or more resource bundle property files. * * <pre> * TransportText_en_US.properties: * repositoryNotFound=repository {0} not found * transportError=unknown error talking to {0} * TransportText_de.properties: * repositoryNotFound=repository {0} nicht gefunden * transportError=unbekannter Fehler whrend der Kommunikation mit {0} * ... * </pre> * * Then make use of it: * * <pre> * NLS.setLocale(Locale.GERMAN); // or skip this call to stick to the JVM default locale * ... * throw new TransportException(uri, TransportText.get().transportError); * </pre> * * The translated text is automatically injected into the public String fields * according to the locale set with * {@link org.eclipse.jgit.nls.NLS#setLocale(Locale)}. However, the * {@link org.eclipse.jgit.nls.NLS#setLocale(Locale)} method defines only * prefered locale which will be honored only if it is supported by the provided * resource bundle property files. Basically, this class will use * {@link java.util.ResourceBundle#getBundle(String, Locale)} method to load a * resource bundle. See the documentation of this method for a detailed * explanation of resource bundle loading strategy. After a bundle is created * the {@link #effectiveLocale()} method can be used to determine whether the * bundle really corresponds to the requested locale or is a fallback. * * <p> * To load a String from a resource bundle property file this class uses the * {@link java.util.ResourceBundle#getString(String)}. This method can throw the * {@link java.util.MissingResourceException} and this class is not making any * effort to catch and/or translate this exception. * * <p> * To define a concrete translation bundle one has to: * <ul> * <li>extend this class * <li>define a public static get() method like in the example above * <li>define public static String fields for each text message * <li>make sure the translation bundle class provide public no arg constructor * <li>provide one or more resource bundle property files in the same package * where the translation bundle class resides * </ul> */ public abstract class TranslationBundle { private Locale effectiveLocale; private ResourceBundle resourceBundle; /** * Get the locale used for loading the resource bundle from which the field * values were taken. * * @return the locale used for loading the resource bundle from which the * field values were taken. */ public Locale effectiveLocale() { return effectiveLocale; } /** * Get the resource bundle on which this translation bundle is based. * * @return the resource bundle on which this translation bundle is based. */ public ResourceBundle resourceBundle() { return resourceBundle; } /** * Injects locale specific text in all instance fields of this instance. * Only public instance fields of type <code>String</code> are considered. * <p> * The name of this (sub)class plus the given <code>locale</code> parameter * define the resource bundle to be loaded. In other words the * <code>this.getClass().getName()</code> is used as the * <code>baseName</code> parameter in the * {@link ResourceBundle#getBundle(String, Locale)} parameter to load the * resource bundle. * <p> * * @param locale * defines the locale to be used when loading the resource bundle * @exception TranslationBundleLoadingException * see {@link TranslationBundleLoadingException} * @exception TranslationStringMissingException * see {@link TranslationStringMissingException} */ void load(Locale locale) throws TranslationBundleLoadingException { Class bundleClass = getClass(); try { resourceBundle = ResourceBundle.getBundle(bundleClass.getName(), locale, bundleClass.getClassLoader()); } catch (MissingResourceException e) { throw new TranslationBundleLoadingException(bundleClass, locale, e); } this.effectiveLocale = resourceBundle.getLocale(); for (Field field : bundleClass.getFields()) { if (field.getType().equals(String.class)) { try { String translatedText = resourceBundle.getString(field.getName()); field.set(this, translatedText); } catch (MissingResourceException e) { throw new TranslationStringMissingException(bundleClass, locale, field.getName(), e); } catch (IllegalArgumentException | IllegalAccessException e) { throw new Error(e); } } } } }