Java tutorial
/** * Copyright (C) 2010 Orbeon, Inc. * * This program 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 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 Lesser General Public License for more details. * * The full text of the license is available at http://www.gnu.org/copyleft/lesser.html */ package org.orbeon.oxf.properties; import org.apache.log4j.Logger; import org.dom4j.Document; import org.dom4j.QName; import org.orbeon.oxf.common.OXFException; import org.orbeon.oxf.pipeline.api.PipelineContext; import org.orbeon.oxf.processor.DOMSerializer; import org.orbeon.oxf.processor.Processor; import org.orbeon.oxf.processor.ProcessorImpl; import org.orbeon.oxf.util.LoggerFactory; import org.orbeon.oxf.util.PipelineUtils; import java.util.Set; /** * This class provides access to global, configurable properties, as well as to processor-specific properties. This is * an example of properties file: * * <properties xmlns:xs="http://www.w3.org/2001/XMLSchema" * xmlns:oxf="http://www.orbeon.com/oxf/processors"> * * <property as="xs:integer" name="oxf.cache.size" value="200"/> * <property as="xs:string" processor-name="oxf:page-flow" name="instance-passing" value="redirect"/> * * </properties> */ public class Properties { private static final Logger logger = LoggerFactory.createLogger(Properties.class); public static final String DEFAULT_PROPERTIES_URI = "oxf:/properties.xml"; public static final String PROPERTIES_SCHEMA_URI = "http://www.orbeon.com/oxf/properties"; private static final int RELOAD_DELAY = 5 * 1000; /** * The global Properties instance. */ private static Properties instance; private static String propertiesURI = DEFAULT_PROPERTIES_URI; private static boolean initializing = false; /** * The property store. */ private PropertyStore propertyStore = null; // Used for refresh private Processor urlGenerator; private DOMSerializer domSerializer; private long lastUpdate = Long.MIN_VALUE; private Properties() { // Don't allow creation from outside } /** * Set URI of the resource we will read the properties from. */ public static void init(String propertiesURI) { Properties.propertiesURI = propertiesURI; instance(); } /** * Invalidate all properties (for testing). */ public static void invalidate() { instance = null; } /** * Return the global Properties. * * @return Properties */ public static Properties instance() { if (instance == null) { instance = new Properties(); instance.update(); } return instance; } /** * Make sure we have the latest properties, and if we don't (resource changed), reload them. */ private void update() { if (!initializing) { done: try { initializing = true; final long current = System.currentTimeMillis(); if (lastUpdate + RELOAD_DELAY >= current) break done; // Create mini-pipeline to read properties if needed if (urlGenerator == null) { urlGenerator = PipelineUtils.createURLGenerator(propertiesURI, true);// enable XInclude too domSerializer = new DOMSerializer(); PipelineUtils.connect(urlGenerator, ProcessorImpl.OUTPUT_DATA, domSerializer, ProcessorImpl.INPUT_DATA); } // Initialize pipeline // Candidate for Scala withPipelineContext final PipelineContext pipelineContext = new PipelineContext(); boolean success = false; try { urlGenerator.reset(pipelineContext); domSerializer.reset(pipelineContext); // Find whether we can skip reloading if (propertyStore != null && domSerializer.findInputLastModified(pipelineContext) <= lastUpdate) { if (logger.isDebugEnabled()) { logger.debug("Not reloading properties because they have not changed."); } lastUpdate = current; success = true; break done; } if (logger.isDebugEnabled()) { logger.debug("Reloading properties because timestamp indicates they may have changed."); } // Read updated properties document final Document document = domSerializer.runGetDocument(pipelineContext); if (document == null || document.content() == null || document.content().size() == 0) { throw new OXFException("Failure to initialize Orbeon Forms properties"); } propertyStore = new PropertyStore(document); lastUpdate = current; success = true; } finally { pipelineContext.destroy(success); } } finally { initializing = false; } } } public PropertySet getPropertySet() { if (propertyStore == null) return null; update(); return propertyStore.getGlobalPropertySet(); } public PropertySet getPropertySet(final QName processorName) { if (propertyStore == null) return null; update(); return propertyStore.getProcessorPropertySet(processorName); } public Set keySet() { if (propertyStore == null) return null; return propertyStore.getGlobalPropertySet().keySet(); } }