Java tutorial
/** * Copyright 2009, 2010 The Regents of the University of California * Licensed under the Educational Community License, Version 2.0 * (the "License"); you may not use this file except in compliance * with the License. You may obtain a copy of the License at * * http://www.osedu.org/licenses/ECL-2.0 * * Unless required by applicable law or agreed to in writing, * software distributed under the License is distributed on an "AS IS" * BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express * or implied. See the License for the specific language governing * permissions and limitations under the License. * */ package org.opencastproject.mediapackage.elementbuilder; import org.opencastproject.mediapackage.Catalog; import org.opencastproject.mediapackage.CatalogImpl; import org.opencastproject.mediapackage.MediaPackageElement; import org.opencastproject.mediapackage.MediaPackageElement.Type; import org.opencastproject.mediapackage.MediaPackageElementFlavor; import org.opencastproject.mediapackage.MediaPackageReferenceImpl; import org.opencastproject.mediapackage.MediaPackageSerializer; import org.opencastproject.mediapackage.UnsupportedElementException; import org.opencastproject.util.Checksum; import org.opencastproject.util.MimeType; import org.opencastproject.util.MimeTypes; import org.apache.commons.lang.StringUtils; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.w3c.dom.Node; import org.w3c.dom.NodeList; import java.net.URI; import java.net.URISyntaxException; import java.security.NoSuchAlgorithmException; import javax.xml.xpath.XPath; import javax.xml.xpath.XPathConstants; import javax.xml.xpath.XPathExpressionException; import javax.xml.xpath.XPathFactory; /** * This implementation of the {@link MediaPackageElementBuilderPlugin} recognizes metadata catalogs and provides the * functionality of reading it on behalf of the media package. */ public class CatalogBuilderPlugin implements MediaPackageElementBuilderPlugin { /** The xpath facility */ protected XPath xpath = XPathFactory.newInstance().newXPath(); /** * the logging facility provided by log4j */ private static final Logger logger = LoggerFactory.getLogger(CatalogBuilderPlugin.class); /** * @see org.opencastproject.mediapackage.elementbuilder.MediaPackageElementBuilderPlugin#accept(org.opencastproject.mediapackage.MediaPackageElement.Type, * org.opencastproject.mediapackage.MediaPackageElementFlavor) */ public boolean accept(MediaPackageElement.Type type, MediaPackageElementFlavor flavor) { return type.equals(MediaPackageElement.Type.Catalog); } /** * @see org.opencastproject.mediapackage.elementbuilder.MediaPackageElementBuilderPlugin#accept(org.w3c.dom.Node) */ public boolean accept(Node elementNode) { String name = elementNode.getNodeName(); if (name.contains(":")) { name = name.substring(name.indexOf(":") + 1); } return name.equalsIgnoreCase(MediaPackageElement.Type.Catalog.toString()); } /** * @see org.opencastproject.mediapackage.elementbuilder.MediaPackageElementBuilderPlugin#accept(URI, * org.opencastproject.mediapackage.MediaPackageElement.Type, * org.opencastproject.mediapackage.MediaPackageElementFlavor) */ public boolean accept(URI uri, MediaPackageElement.Type type, MediaPackageElementFlavor flavor) { return MediaPackageElement.Type.Catalog.equals(type); } /** * @see org.opencastproject.mediapackage.elementbuilder.MediaPackageElementBuilderPlugin#elementFromURI(URI) */ public MediaPackageElement elementFromURI(URI uri) throws UnsupportedElementException { logger.trace("Creating video track from " + uri); Catalog track = CatalogImpl.fromURI(uri); return track; } @Override public String toString() { return "Indefinite Catalog Builder Plugin"; } protected Catalog catalogFromManifest(String id, URI uri) { Catalog cat = CatalogImpl.fromURI(uri); cat.setIdentifier(id); return cat; } /** * {@inheritDoc} * * @see org.opencastproject.mediapackage.elementbuilder.MediaPackageElementBuilderPlugin#destroy() */ @Override public void destroy() { } /** * {@inheritDoc} * * @see org.opencastproject.mediapackage.elementbuilder.MediaPackageElementBuilderPlugin#elementFromManifest(org.w3c.dom.Node, * org.opencastproject.mediapackage.MediaPackageSerializer) */ @Override public MediaPackageElement elementFromManifest(Node elementNode, MediaPackageSerializer serializer) throws UnsupportedElementException { String id = null; String flavor = null; URI url = null; long size = -1; Checksum checksum = null; MimeType mimeType = null; String reference = null; try { // id id = (String) xpath.evaluate("@id", elementNode, XPathConstants.STRING); // url url = serializer.resolvePath(xpath.evaluate("url/text()", elementNode).trim()); // flavor flavor = (String) xpath.evaluate("@type", elementNode, XPathConstants.STRING); // reference reference = (String) xpath.evaluate("@ref", elementNode, XPathConstants.STRING); // size String documentSize = xpath.evaluate("size/text()", elementNode).trim(); if (!"".equals(documentSize)) size = Long.parseLong(documentSize); // checksum String checksumValue = (String) xpath.evaluate("checksum/text()", elementNode, XPathConstants.STRING); String checksumType = (String) xpath.evaluate("checksum/@type", elementNode, XPathConstants.STRING); if (StringUtils.isNotEmpty(checksumValue) && checksumType != null) checksum = Checksum.create(checksumType.trim(), checksumValue.trim()); // mimetype String mimeTypeValue = (String) xpath.evaluate("mimetype/text()", elementNode, XPathConstants.STRING); if (StringUtils.isNotEmpty(mimeTypeValue)) mimeType = MimeTypes.parseMimeType(mimeTypeValue); // create the catalog Catalog dc = CatalogImpl.fromURI(url); if (StringUtils.isNotEmpty(id)) dc.setIdentifier(id); // Add url dc.setURI(url); // Add flavor if (flavor != null) dc.setFlavor(MediaPackageElementFlavor.parseFlavor(flavor)); // Add reference if (StringUtils.isNotEmpty(reference)) dc.referTo(MediaPackageReferenceImpl.fromString(reference)); // Set size if (size > 0) dc.setSize(size); // Set checksum if (checksum != null) dc.setChecksum(checksum); // Set Mimetype if (mimeType != null) dc.setMimeType(mimeType); // Tags NodeList tagNodes = (NodeList) xpath.evaluate("tags/tag", elementNode, XPathConstants.NODESET); for (int i = 0; i < tagNodes.getLength(); i++) { dc.addTag(tagNodes.item(i).getTextContent()); } return dc; } catch (XPathExpressionException e) { throw new UnsupportedElementException( "Error while reading catalog information from manifest: " + e.getMessage()); } catch (NoSuchAlgorithmException e) { throw new UnsupportedElementException("Unsupported digest algorithm: " + e.getMessage()); } catch (URISyntaxException e) { throw new UnsupportedElementException( "Error while reading dublin core catalog " + url + ": " + e.getMessage()); } } /** * {@inheritDoc} * * @see org.opencastproject.mediapackage.elementbuilder.MediaPackageElementBuilderPlugin#newElement(org.opencastproject.mediapackage.MediaPackageElement.Type, * org.opencastproject.mediapackage.MediaPackageElementFlavor) */ @Override public MediaPackageElement newElement(Type type, MediaPackageElementFlavor flavor) { Catalog cat = CatalogImpl.newInstance(); cat.setFlavor(flavor); return cat; } /** * {@inheritDoc} * * @see org.opencastproject.mediapackage.elementbuilder.MediaPackageElementBuilderPlugin#init() */ @Override public void init() throws Exception { } }