org.opencastproject.mediapackage.MediaPackageBuilderImpl.java Source code

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Here is the source code for org.opencastproject.mediapackage.MediaPackageBuilderImpl.java

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/**
 *  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;

import org.opencastproject.mediapackage.identifier.Id;

import org.apache.commons.io.IOUtils;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

import java.io.IOException;
import java.io.InputStream;
import java.net.URISyntaxException;

import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;

/**
 * This class provides factory methods for the creation of media packages from manifest files, directories or from
 * scratch. This class is not thread safe, so create a new builder in each method invocation.
 */
public class MediaPackageBuilderImpl implements MediaPackageBuilder {

    /** The media package serializer */
    protected MediaPackageSerializer serializer = null;

    /**
     * Creates a new media package builder.
     * 
     * @throws IllegalStateException
     *           if the temporary directory cannot be created or is not accessible
     */
    public MediaPackageBuilderImpl() {
    }

    /**
     * Creates a new media package builder that uses the given serializer to resolve urls while reading manifests and
     * adding new elements.
     * 
     * @param serializer
     *          the media package serializer
     * @throws IllegalStateException
     *           if the temporary directory cannot be created or is not accessible
     */
    public MediaPackageBuilderImpl(MediaPackageSerializer serializer) {
        if (serializer == null)
            throw new IllegalArgumentException("Serializer may not be null");
        this.serializer = serializer;
    }

    /**
     * {@inheritDoc}
     * 
     * @see org.opencastproject.mediapackage.MediaPackageBuilder#createNew()
     */
    public MediaPackage createNew() throws MediaPackageException {
        return new MediaPackageImpl();
    }

    /**
     * {@inheritDoc}
     * 
     * @see org.opencastproject.mediapackage.MediaPackageBuilder#createNew(org.opencastproject.mediapackage.identifier.Id)
     */
    public MediaPackage createNew(Id identifier) throws MediaPackageException {
        return new MediaPackageImpl(identifier);
    }

    /**
     * {@inheritDoc}
     * 
     * @see org.opencastproject.mediapackage.MediaPackageBuilder#loadFromXml(java.io.InputStream)
     */
    public MediaPackage loadFromXml(InputStream is) throws MediaPackageException {
        if (serializer != null) {
            // FIXME This code runs if *any* serializer is present, regardless of the serializer implementation
            try {
                Document xml = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(is);
                rewriteUrls(xml, serializer);
                return MediaPackageImpl.valueOf(xml);
            } catch (Exception e) {
                throw new MediaPackageException("Error deserializing paths in media package", e);
            }
        } else {
            return MediaPackageImpl.valueOf(is);
        }
    }

    /**
     * @see org.opencastproject.mediapackage.MediaPackageBuilder#getSerializer()
     */
    public MediaPackageSerializer getSerializer() {
        return serializer;
    }

    /**
     * @see org.opencastproject.mediapackage.MediaPackageBuilder#setSerializer(org.opencastproject.mediapackage.MediaPackageSerializer)
     */
    public void setSerializer(MediaPackageSerializer serializer) {
        this.serializer = serializer;
    }

    /**
     * {@inheritDoc}
     * 
     * @see org.opencastproject.mediapackage.MediaPackageBuilder#loadFromXml(java.lang.String)
     */
    @Override
    public MediaPackage loadFromXml(String xml) throws MediaPackageException {
        InputStream in = null;
        try {
            in = IOUtils.toInputStream(xml, "UTF-8");
            return loadFromXml(in);
        } catch (IOException e) {
            throw new MediaPackageException(e);
        } finally {
            IOUtils.closeQuietly(in);
        }
    }

    @Override
    public MediaPackage loadFromXml(Node xml) throws MediaPackageException {
        if (serializer != null) {
            // FIXME This code runs if *any* serializer is present, regardless of the serializer implementation
            try {
                rewriteUrls(xml, serializer);
                return MediaPackageImpl.valueOf(xml);
            } catch (Exception e) {
                throw new MediaPackageException("Error deserializing paths in media package", e);
            }
        } else {
            return MediaPackageImpl.valueOf(xml);
        }
    }

    /**
     * Rewrite the url elements using the serializer. Attention: This method modifies the given DOM!
     */
    private static void rewriteUrls(Node xml, MediaPackageSerializer serializer)
            throws XPathExpressionException, URISyntaxException {
        XPath xPath = XPathFactory.newInstance().newXPath();
        NodeList nodes = (NodeList) xPath.evaluate("//*[local-name() = 'url']", xml, XPathConstants.NODESET);
        for (int i = 0; i < nodes.getLength(); i++) {
            Node uri = nodes.item(i).getFirstChild();
            if (uri != null)
                uri.setNodeValue(serializer.resolvePath(uri.getNodeValue()).toString());
        }
    }

}