Java tutorial
/* * See the NOTICE file distributed with this work for additional * information regarding copyright ownership. * * This is free software; you can redistribute it and/or modify it * under the terms of the GNU Lesser General Public License as * published by the Free Software Foundation; either version 2.1 of * the License, or (at your option) any later version. * * This software is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this software; if not, write to the Free * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA * 02110-1301 USA, or see the FSF site: http://www.fsf.org. */ package org.xwiki.localization.internal; import java.io.ByteArrayInputStream; import java.io.IOException; import java.io.InputStream; import java.io.UnsupportedEncodingException; import java.util.Enumeration; import java.util.HashMap; import java.util.Map; import java.util.Properties; import org.apache.commons.lang3.StringUtils; import org.xwiki.bridge.DocumentAccessBridge; import org.xwiki.bridge.DocumentModelBridge; import org.xwiki.component.annotation.Requirement; import org.xwiki.localization.Bundle; import org.xwiki.localization.WikiInformation; import org.xwiki.observation.EventListener; import org.xwiki.observation.ObservationManager; import org.xwiki.observation.event.DocumentDeleteEvent; import org.xwiki.observation.event.DocumentSaveEvent; import org.xwiki.observation.event.DocumentUpdateEvent; import org.xwiki.observation.event.Event; import org.xwiki.observation.event.filter.EventFilter; import org.xwiki.observation.event.filter.FixedNameEventFilter; /** * Base class for {@link Bundle}s using wiki documents as resources. Provides methods for loading properties from * documents, watching loaded documents and invalidating cached translations. * * @version $Id: f67bd19fb526c17878aa865e9182a0dc49cc29ef $ */ public abstract class AbstractWikiBundle extends AbstractBundle implements Bundle, EventListener { /** The encoding used for storing unicode characters as bytes. */ protected static final String UNICODE_BYTE_ENCODING = "UTF-8"; /** The encoding assumed by the ResourceBundle loader. */ protected static final String DEFAULT_RESOURCE_BYTE_ENCODING = "ISO-8859-1"; /** Allows to register for receiving notifications about document changes. */ @Requirement protected ObservationManager observation; /** Provides access to documents. */ @Requirement protected DocumentAccessBridge documentAccessBridge; /** * Caching the default language for each wiki. */ protected Map<String, String> defaultWikiLanguage = new HashMap<String, String>(); /** * <p> * Cached properties corresponding to resources loaded from wiki documents. * </p> * <p> * Map: (document name -> map: (language -> properties)). The document name is always prefixed with the wiki * name. * </p> */ protected Map<String, Map<String, Properties>> documentBundles = new HashMap<String, Map<String, Properties>>(); /** * Retrieves the properties loaded from the document. If these properties are already cached, then use them. * Otherwise, first load from the wiki and update the cache. * * @param documentName The full name of the source document, including the wiki prefix. * @param language The translation to retrieve. * @return A {@link Properties} object corresponding to the document translation, including as a base the default * language values for the keys that are not defined in the requested translation. * @throws Exception if the document cannot be accessed. * @see #loadDocumentBundle(String, String) */ protected Properties getDocumentBundle(String documentName, String language) throws Exception { synchronized (this.documentBundles) { if (this.documentBundles.containsKey(documentName)) { if (this.documentBundles.get(documentName).containsKey(language)) { return this.documentBundles.get(documentName).get(language); } } else { this.documentBundles.put(documentName, new HashMap<String, Properties>()); } Properties result = loadDocumentBundle(documentName, language); this.documentBundles.get(documentName).put(language, result); watchDocument(documentName); return result; } } /** * Loads translations from a document, in a specified language. If the requested language is not the same as the * default wiki language, then the translations in the default language are first loaded as a base translation. * Additionally, the document is added to the list of watched documents, so that changes in the document are * detected. * * @param documentName The full name of the source document, including the wiki prefix. * @param language The translation to load. * @return A {@link Properties} object loaded from the translation, including as a base the default language values * for the keys that are not defined in the requested translation. * @throws Exception if the document cannot be accessed. * @see #loadDocumentBundle(String, String, String) */ protected Properties loadDocumentBundle(String documentName, String language) throws Exception { String wiki; if (documentName.indexOf(WikiInformation.WIKI_PREFIX_SEPARATOR) > 0) { wiki = StringUtils.substringBefore(documentName, WikiInformation.WIKI_PREFIX_SEPARATOR); } else { wiki = this.wikiInfo.getCurrentWikiName(); } return loadDocumentBundle(wiki, documentName, language); } /** * Loads translations from a document, in a specified language. If the requested language is not the same as the * default wiki language, then the translations in the default language are first loaded as a base translation. * Additionally, the document is added to the list of watched documents, so that changes in the document are * detected. * * @param wiki The wiki containing the document. * @param documentName The full name of the source document, including the wiki prefix. * @param language The translation to load. * @return A {@link Properties} object loaded from the translation, including as a base the default language values * for the keys that are not defined in the requested translation. * @throws Exception if the document cannot be accessed. * @see #loadPropertiesFromString(Properties, String, String) */ protected Properties loadDocumentBundle(String wiki, String documentName, String language) throws Exception { Properties properties = new Properties(); String defaultContent = this.documentAccessBridge.getDocumentContent(documentName, this.wikiInfo.getDefaultWikiLanguage()); loadPropertiesFromString(properties, defaultContent, documentName); if (!StringUtils.equals(language, getDefaultWikiLanguage(wiki))) { String content = this.documentAccessBridge.getDocumentContent(documentName, language); loadPropertiesFromString(properties, content, documentName); } watchDocument(documentName); return properties; } /** * <p> * Loads the translations defined in a document into an existing {@link Properties} object. Old values from the * passed Properties are overwritten when translations are found in the document content. * </p> * <p> * Since the Properties {@link Properties#load(InputStream) load} method always assumes the stream contains only * ISO-8859-1 characters, we need to embed somehow Unicode characters outside the 8859-1 encoding into the input * stream. We achieve this by explicitly splitting the content into UTF-8 bytes, which are then read as a byte * stream. When loaded, the properties are wrongly created by interpreting those bytes are ISO-8859-1 characters, so * we must re-split and re-combine each property back into the UTF-8 encoding. Although this is time consuming, the * alternative is to re-implement the Properties class so that it accepts a proper character input stream. And * besides, resources are supposed to be loaded only once in real live wikis. * </p> * * @param props The {@link Properties} object to enhance. It is modified inside the method body. * @param content The content from which to load translations. * @param documentName The name of the container wiki document. Needed for logging only. * @return The enhanced properties file, the same object as the <tt>props</tt> parameter. */ protected Properties loadPropertiesFromString(Properties props, String content, String documentName) { byte[] bcontent; Properties temp = new Properties(); try { // We force splitting into UTF-8 since it is supposed to be available on all platforms, and it can represent // all unicode characters. bcontent = content.getBytes(UNICODE_BYTE_ENCODING); } catch (UnsupportedEncodingException ex) { // This should not happen, ever! If it does, there is something wrong in the system. getLogger().error("Error splitting a document resource bundle into bytes using the UTF-8 encoding", ex); bcontent = content.getBytes(); } InputStream is = new ByteArrayInputStream(bcontent); try { temp.load(is); // Adds new properties into the existing object, overriding old values, but not clearing completely. for (Enumeration<?> keys = temp.propertyNames(); keys.hasMoreElements();) { String key = (String) keys.nextElement(); props.setProperty(key, new String(temp.getProperty(key).getBytes(DEFAULT_RESOURCE_BYTE_ENCODING), UNICODE_BYTE_ENCODING)); } } catch (IOException ex) { // Cannot do anything more getLogger().error("Invalid document resource bundle: [{0}]", ex, documentName); } return props; } /** * Retrieves the default language configured for a wiki. This method uses a cache, If a value is defined in the * cache, then return it. Otherwise, ask the setting from {@link AbstractBundle#wikiInfo} and add it to the cache. * This method does not detect stale values, the cache will be invalidated when changes to the preferences document * are detected. * * @param wiki The target wiki whose default language is to be determined. * @return The 2-character code of the default language of the wiki. */ protected String getDefaultWikiLanguage(String wiki) { synchronized (this.defaultWikiLanguage) { if (this.defaultWikiLanguage.containsKey(wiki)) { return this.defaultWikiLanguage.get(wiki); } String result = this.wikiInfo.getDefaultWikiLanguage(wiki); this.defaultWikiLanguage.put(wiki, result); return result; } } /** * Sets a new value in the default wiki language cache, informing whether the old value was changed or not. * * @param wiki The target wiki whose default language is to be set. * @param language The 2-character code of the new default language of the wiki. * @return <code>false</code> if the previous value was the same as the new value (the language didn't change), * <code>true</code> otherwise. */ protected boolean setDefaultWikiLanguage(String wiki, String language) { synchronized (this.defaultWikiLanguage) { return !StringUtils.equals(this.defaultWikiLanguage.put(wiki, language), language); } } /** * Registers for events on a specific document. * * @param documentName the full name of the document to watch */ protected void watchDocument(String documentName) { // addListener ignores duplicates, so it is safe to add a listener many times. EventFilter filter = new FixedNameEventFilter(documentName); this.observation.addListener(new DocumentUpdateEvent(filter), this); this.observation.addListener(new DocumentSaveEvent(filter), this); this.observation.addListener(new DocumentDeleteEvent(filter), this); } /** * {@inheritDoc} * <p> * Invalidates cached properties depending on the changed documents. * </p> * * @see EventListener#onEvent(Event, Object, Object) */ public void onEvent(Event event, Object source, Object data) { // - if doc is a cached bundle // -- if is default language // --- invalidate all the document's bundles // -- else if translation is cached // --- invalidate the translated bundle DocumentModelBridge doc = (DocumentModelBridge) source; DocumentModelBridge oldDoc = doc.getOriginalDocument(); if (oldDoc == null || doc.getContent().equals(oldDoc.getContent())) { // Since translations are kept inside the document content, then if the content didn't change, there's no // need to invalidate the cached properties. return; } String docName = doc.getWikiName() + ":" + doc.getFullName(); synchronized (this.documentBundles) { if (this.documentBundles.containsKey(docName)) { if (doc.getRealLanguage().equals(getDefaultWikiLanguage(doc.getWikiName()))) { // Default language, invalidate all document bundles this.documentBundles.remove(docName); } else if (this.documentBundles.get(docName).containsKey(doc.getRealLanguage())) { // Invalidate just the translation this.documentBundles.get(docName).remove(doc.getRealLanguage()); } } } } }