Java tutorial
/*************************************************************** * This file is part of the [fleXive](R) framework. * * Copyright (c) 1999-2014 * UCS - unique computing solutions gmbh (http://www.ucs.at) * All rights reserved * * The [fleXive](R) project is free software; you can redistribute * it and/or modify it under the terms of the GNU Lesser General Public * License version 2.1 or higher as published by the Free Software Foundation. * * The GNU Lesser General Public License can be found at * http://www.gnu.org/licenses/lgpl.html. * A copy is found in the textfile LGPL.txt and important notices to the * license from the author are found in LICENSE.txt distributed with * these libraries. * * This library 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. * * For further information about UCS - unique computing solutions gmbh, * please see the company website: http://www.ucs.at * * For further information about [fleXive](R), please see the * project website: http://www.flexive.org * * * This copyright notice MUST APPEAR in all copies of the file! ***************************************************************/ package com.flexive.shared.media; import com.flexive.shared.exceptions.FxApplicationException; import org.apache.commons.lang.StringUtils; import javax.xml.stream.XMLOutputFactory; import javax.xml.stream.XMLStreamException; import javax.xml.stream.XMLStreamWriter; import java.io.Serializable; import java.io.StringWriter; import java.util.List; /** * Generic media metadata * * @author Markus Plesser (markus.plesser@flexive.com), UCS - unique computing solutions gmbh (http://www.ucs.at) * @version $Rev$ */ public abstract class FxMetadata { private static XMLOutputFactory xmlOutputFactory; /** * An item holding metadata */ public static class FxMetadataItem implements Serializable { private static final long serialVersionUID = -4856169406370122927L; private String key; private String value; /** * Ctor * * @param key key * @param value valud */ public FxMetadataItem(String key, String value) { this.key = key; this.value = value; } /** * Getter for the key * * @return key */ public String getKey() { return key; } /** * Getter for the value * * @return value */ public String getValue() { return value; } } /** * Get the type of this metadata instance to allow easier upcasts * * @return type of this metadata instance */ public abstract FxMediaType getMediaType(); /** * Get the mime type * * @return mime type */ public abstract String getMimeType(); /** * Get the file name, can be <code>null</code> if unknown * * @return filename or <code>null</code> */ public abstract String getFilename(); /** * Get a list of defined metadata items * * @return list of defined metadata items */ public abstract List<FxMetadataItem> getMetadata(); /** * Check if this metadata object is an image metadata instance * * @return this object is an image meta data instance * @since 3.1 */ public boolean isImageMetadata() { return false; } /** * Check if this metadata object is an audio metadata instance * * @return true if this object is an audio metadata instance * @since 3.1.2 */ public boolean isAudioMetadata() { return false; } /** * Check if this metadata object is a video metadata instance * * @return true if this object is an audio metadata instance * @since 3.1.3 */ public boolean isVideoMetadata() { return false; } /** * Get this metadata object as an FxImageMetadata instance * * @return FxImageMetadata instance * @throws FxApplicationException on errors */ public FxImageMetadata asImageMetadata() throws FxApplicationException { if (this instanceof FxImageMetadata) return (FxImageMetadata) this; throw new FxApplicationException("ex.general.wrongClass", this.getClass().getCanonicalName(), FxImageMetadata.class.getCanonicalName()); } /** * Get this metadata object as XML document * * @return XML document * @throws FxApplicationException on errors */ public String toXML() throws FxApplicationException { StringWriter sw = new StringWriter(2000); try { XMLStreamWriter writer = getXmlOutputFactory().createXMLStreamWriter(sw); writer.writeStartDocument(); writer.writeStartElement("metadata"); writer.writeAttribute("mediatype", getMediaType().name()); writer.writeAttribute("mimetype", getMimeType()); writer.writeAttribute("filename", getFilename()); writeXMLTags(writer); for (FxMetadataItem mdi : getMetadata()) { final String value = mdi.getValue().replaceAll("[\\x00-\\x1F]", ""); //filter out control characters if (StringUtils.isEmpty(value)) continue; writer.writeStartElement("meta"); writer.writeAttribute("key", mdi.getKey()); writer.writeCData(value); writer.writeEndElement(); } writer.writeEndElement(); writer.writeEndDocument(); writer.flush(); writer.close(); } catch (XMLStreamException e) { throw new FxApplicationException(e, "ex.general.xml", e.getMessage()); } return sw.getBuffer().toString(); } private static synchronized XMLOutputFactory getXmlOutputFactory() { if (xmlOutputFactory == null) { // cache the factory since profiling showed that this is a rather expensive call xmlOutputFactory = XMLOutputFactory.newInstance(); } return xmlOutputFactory; } /** * Write implementation specific XML tags * * @param writer XMLStreamWriter * @throws XMLStreamException on errors */ protected abstract void writeXMLTags(XMLStreamWriter writer) throws XMLStreamException; }