XmlUtil.java

/*******************************************************************************
 * Copyright (c) 2011, 2016 Eurotech and/or its affiliates
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     Eurotech
 *******************************************************************************/
package org.eclipse.kura.core.configuration.util;

import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;
import java.io.StringWriter;
import java.io.Writer;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.stream.FactoryConfigurationError;
import javax.xml.stream.XMLStreamException;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;

import org.eclipse.kura.core.configuration.XmlComponentConfigurations;
import org.eclipse.kura.core.configuration.XmlSnapshotIdResult;
import org.eclipse.kura.core.configuration.util.serializers.XmlJavaComponentConfigurationsMapper;
import org.eclipse.kura.core.configuration.util.serializers.XmlJavaMetadataMapper;
import org.eclipse.kura.core.configuration.util.serializers.XmlJavaSnapshotIdResultMapper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.w3c.dom.Document;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

public class XmlUtil {

    private static final Logger s_logger = LoggerFactory.getLogger(XmlUtil.class);

    //
    // Public methods
    //

    // Marshalling
    public static String marshal(Object object) throws Exception {
        StringWriter sw = new StringWriter();
        marshal(object, sw);
        return sw.toString();
    }

    public static void marshal(Object object, Writer w) throws Exception {
        try {
            DocumentBuilderFactory docFactory = DocumentBuilderFactory.newInstance();
            DocumentBuilder docBuilder = docFactory.newDocumentBuilder();

            // root elements
            Document doc = docBuilder.newDocument();
            doc.setXmlStandalone(true);

            if (object instanceof XmlSnapshotIdResult) {
                // Resulting xml:
                // <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
                // <esf:snapshot-ids xmlns:ocd="http://www.osgi.org/xmlns/metatype/v1.2.0"
                // xmlns:esf="http://eurotech.com/esf/2.0">
                // <esf:snapshotIds>1434122113492</esf:snapshotIds>
                // <esf:snapshotIds>1434122124387</esf:snapshotIds>
                // </esf:snapshot-ids>

                new XmlJavaSnapshotIdResultMapper().marshal(doc, object);

            } else if (object instanceof XmlComponentConfigurations) {
                new XmlJavaComponentConfigurationsMapper().marshal(doc, object);
            }

            // write the content into xml file
            TransformerFactory transformerFactory = TransformerFactory.newInstance();
            Transformer transformer = transformerFactory.newTransformer();
            transformer.setOutputProperty(OutputKeys.INDENT, "yes");
            transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "4");
            DOMSource source = new DOMSource(doc);

            StreamResult result = new StreamResult(w); // System.out
            transformer.transform(source, result);
        } catch (ParserConfigurationException pce) {
            s_logger.warn("Parser Exception", pce);
        } catch (TransformerException tfe) {
            s_logger.warn("Transformer Exception", tfe);
        }
    }

    // un-marshalling
    public static <T> T unmarshal(String s, Class<T> clazz) throws XMLStreamException, FactoryConfigurationError {
        StringReader sr = new StringReader(s);
        T result = unmarshal(sr, clazz);
        return result;
    }

    public static <T> T unmarshal(Reader r, Class<T> clazz) throws XMLStreamException, FactoryConfigurationError {
        DocumentBuilderFactory factory = null;
        DocumentBuilder parser = null;

        try {
            factory = DocumentBuilderFactory.newInstance();
            // factory.setValidating(true);
            parser = factory.newDocumentBuilder();
        } catch (FactoryConfigurationError fce) {
            // The implementation is not available or cannot be instantiated
            s_logger.error("Parser Factory configuration Error");
            throw fce;
        } catch (ParserConfigurationException pce) {
            // the parser cannot be created with the specified configuration
            s_logger.error("Parser configuration exception");
            throw new FactoryConfigurationError(pce);
        }

        // parse the document
        Document doc = null;
        try {
            InputSource is = new InputSource(r);
            doc = parser.parse(is);
            doc.getDocumentElement().normalize();
        } catch (SAXException se) {
            throw new XMLStreamException(se.getMessage());
        } catch (IOException ioe) {
            throw new XMLStreamException(ioe.getMessage());
        } catch (IllegalArgumentException iae) {
            throw new XMLStreamException(iae.getMessage());
        }

        // identify the correct parser that has to execute
        if (clazz.equals(XmlComponentConfigurations.class)) {
            try {
                // Snapshot parser
                return new XmlJavaComponentConfigurationsMapper().unmarshal(doc);
            } catch (Exception e) {
                throw new XMLStreamException(e.getMessage());
            }
        } else {
            // MetaData parser
            return new XmlJavaMetadataMapper().unmarshal(doc);
        }
    }
}