Java tutorial
/* Index ECM Engine - A system for managing the capture (when created * or received), classification (cataloguing), storage, retrieval, * revision, sharing, reuse and disposition of documents. * * Copyright (C) 2008 Regione Piemonte * Copyright (C) 2008 Provincia di Torino * Copyright (C) 2008 Comune di Torino * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version 2, * or (at your option) any later version. * * This program 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 General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. * */ package it.doqui.index.ecmengine.client.backoffice; import it.doqui.index.ecmengine.client.backoffice.exception.EcmEngineBackofficeDelegateInstantiationException; import it.doqui.index.ecmengine.client.backoffice.util.EcmEngineBackofficeDelegateConstants; import java.lang.reflect.Constructor; import java.lang.reflect.InvocationTargetException; import java.util.ResourceBundle; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; /** * Classe factory utilizzabile per caricare una nuova istanza * del client delegate dei servizi di backoffice. * * <p>Questa classe non è istanziabile, ma fornisce un metodo * {@code static} che restituisce la nuova istanza. Alcuni dei parametri * di funzionamento della factory sono definiti nell'interfaccia * {@link EcmEngineBackofficeDelegateConstants}, altri vengono caricati da * un file di proprietà il cui nome predefinito è * {@code ecmengine-backoffice-delegate.properties} * (vedere anche {@link EcmEngineBackofficeDelegateConstants#ECMENGINE_BKO_PROPERTIES_FILE}). * * @author Doqui * * @see EcmEngineBackofficeDelegateConstants#ECMENGINE_BKO_PROPERTIES_FILE */ public class EcmEngineBackofficeDelegateFactory implements EcmEngineBackofficeDelegateConstants { /** * Costruttore protected definito per nascondere il costruttore * pubblico di default poiché la classe non deve essere * istanziabile. */ protected EcmEngineBackofficeDelegateFactory() { throw new UnsupportedOperationException(); } /** * Metodo factory che crea una nuova istanza del client delegate. * * <p>La factory cerca di istanziare la classe di implementazione * specificata dall'utente nel file di proprietà * {@code ecmengine-backoffice-delegate.properties}. Se tale operazione fallisce * la factory cerca di istanziare la classe di default definita * in {@link EcmEngineBackofficeDelegateConstants#ECMENGINE_BKO_DELEGATE_CLASS_NAME_DEFAULT}. * </p> * * @return Una nuova istanza del client delegate. * * @throws EcmEngineBackofficeDelegateInstantiationException Se si verifica un * errore nell'istanziazione del client delegate. */ public static EcmEngineBackofficeDelegate getEcmEngineBackofficeDelegate() throws EcmEngineBackofficeDelegateInstantiationException { final ResourceBundle resources = ResourceBundle.getBundle(ECMENGINE_BKO_PROPERTIES_FILE); final String caller = resources.getString(ECMENGINE_BKO_DELEGATE_CALLER); final Log logger = LogFactory.getLog(caller + ECMENGINE_BKO_DELEGATE_LOG_CATEGORY); final String implClass = resources.getString(ECMENGINE_BKO_DELEGATE_CLASS); logger.debug("[EcmEngineBackofficeDelegateFactory::getEcmEngineBackofficeDelegate] BEGIN"); EcmEngineBackofficeDelegate backofficeInstance = null; logger.debug("[EcmEngineBackofficeDelegateFactory::getEcmEngineBackofficeDelegate] " + "Classe delegate: " + implClass); try { backofficeInstance = getClassInstance(implClass, logger); } catch (EcmEngineBackofficeDelegateInstantiationException e) { logger.warn("[EcmEngineBackofficeDelegateFactory::getEcmEngineBackofficeDelegate] " + "Impossibile caricare la classe \"" + implClass + "\": " + e.getMessage()); logger.debug("[EcmEngineBackofficeDelegateFactory::getEcmEngineBackofficeDelegate] " + "Classe delegate di default: " + ECMENGINE_BKO_DELEGATE_CLASS_NAME_DEFAULT); try { backofficeInstance = getClassInstance(ECMENGINE_BKO_DELEGATE_CLASS_NAME_DEFAULT, logger); } catch (EcmEngineBackofficeDelegateInstantiationException ex) { logger.error("[EcmEngineBackofficeDelegateFactory::getEcmEngineBackofficeDelegate] " + "Impossibile caricare la classe di default \"" + ECMENGINE_BKO_DELEGATE_CLASS_NAME_DEFAULT + "\": " + ex.getMessage()); throw ex; // Rilancia l'eccezione al chiamante } } finally { logger.debug("[EcmEngineBackofficeDelegateFactory::getEcmEngineBackofficeDelegate] END"); } return backofficeInstance; } private static EcmEngineBackofficeDelegate getClassInstance(String ecmEngineBkoDelegateImplName, Log logger) throws EcmEngineBackofficeDelegateInstantiationException { EcmEngineBackofficeDelegate classInstance = null; logger.debug("[EcmEngineBackofficeDelegateFactory::getClassInstance] BEGIN"); try { logger.debug("[EcmEngineBackofficeDelegateFactory::getClassInstance] " + "Caricamento classe: " + ecmEngineBkoDelegateImplName); final Class delegateClass = Class.forName(ecmEngineBkoDelegateImplName); final Constructor constructor = delegateClass.getConstructor(new Class[] { Log.class }); classInstance = (EcmEngineBackofficeDelegate) constructor.newInstance(new Object[] { logger }); } catch (ClassNotFoundException e) { logger.error("[EcmEngineBackofficeDelegateFactory::getClassInstance] " + "FATAL: classe non trovata."); throw new EcmEngineBackofficeDelegateInstantiationException("Classe non trovata.", e); } catch (NoSuchMethodException e) { logger.error("[EcmEngineBackofficeDelegateFactory::getClassInstance] " + "FATAL: nessun costruttore compatibile."); throw new EcmEngineBackofficeDelegateInstantiationException("Nessun costruttore compatibile.", e); } catch (InstantiationException e) { logger.error( "[EcmEngineBackofficeDelegateFactory::getClassInstance] " + "FATAL: errore di istanziazione."); throw new EcmEngineBackofficeDelegateInstantiationException("Errore di istanziazione.", e); } catch (IllegalAccessException e) { logger.error("[EcmEngineBackofficeDelegateFactory::getClassInstance] " + "FATAL: errore di accesso."); throw new EcmEngineBackofficeDelegateInstantiationException("Errore di accesso.", e); } catch (InvocationTargetException e) { logger.error("[EcmEngineBackofficeDelegateFactory::getClassInstance] " + "FATAL: eccezione nel target invocato."); throw new EcmEngineBackofficeDelegateInstantiationException("Eccezione nel target invocato.", e); } finally { logger.debug("[EcmEngineBackofficeDelegateFactory::getClassInstance] END"); } return classInstance; } }