GmlGeometryConverter.java

/**
 * Copyright (c) Codice Foundation
 *
 * This 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 3 of the
 * License, or 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. A copy of the GNU Lesser General Public License
 * is distributed along with this program and can be found at
 * <http://www.gnu.org/licenses/lgpl.html>.
 *
 **/

package org.codice.ddf.spatial.ogc.wfs.catalog.converter.impl;

import java.io.IOException;
import java.io.StringReader;

import javax.xml.parsers.ParserConfigurationException;

import org.codice.ddf.spatial.ogc.catalog.common.converter.XmlNode;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.xml.sax.SAXException;
import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;

import com.thoughtworks.xstream.converters.Converter;
import com.thoughtworks.xstream.converters.MarshallingContext;
import com.thoughtworks.xstream.converters.UnmarshallingContext;
import com.thoughtworks.xstream.io.HierarchicalStreamReader;
import com.thoughtworks.xstream.io.HierarchicalStreamWriter;
import com.thoughtworks.xstream.io.copy.HierarchicalStreamCopier;
import com.thoughtworks.xstream.io.xml.XppReader;
import com.thoughtworks.xstream.io.xml.xppdom.XppFactory;
import com.vividsolutions.jts.geom.Geometry;
import com.vividsolutions.jts.io.WKTWriter;
import com.vividsolutions.jts.io.gml2.GMLReader;
import com.vividsolutions.jts.io.gml2.GMLWriter;

public class GmlGeometryConverter implements Converter {

    private static final Logger LOGGER = LoggerFactory.getLogger(GmlGeometryConverter.class);

    private static final String ERROR_SERIALIZING_MSG = "Failed to serialize GML from Geometry.";

    private static final String ERROR_PARSING_MSG = "Error parsing Geometry from feature xml.";

    @Override
    public boolean canConvert(Class clazz) {
        return Geometry.class.isAssignableFrom(clazz);
    }

    @Override
    public void marshal(Object value, HierarchicalStreamWriter writer, MarshallingContext context) {
        Geometry geometry = (Geometry) value;
        GMLWriter gmlWriter = new GMLWriter();
        String gmlXml = gmlWriter.write(geometry);
        // Copy the GML XML into the writer
        XmlPullParser parser = null;
        try {
            parser = XppFactory.createDefaultParser();
            new HierarchicalStreamCopier()
                    .copy(new XppReader(new StringReader(gmlXml), parser), writer);
        } catch (XmlPullParserException e) {
            LOGGER.warn(ERROR_SERIALIZING_MSG, e);
        }
    }

    @Override
    public Object unmarshal(HierarchicalStreamReader reader, UnmarshallingContext context) {
        XmlNode gmlNode = new XmlNode(reader);
        GMLReader gmlReader = new GMLReader();
        Geometry geo = null;
        try {
            geo = gmlReader.read(gmlNode.toString(), null);
        } catch (SAXException e) {
            LOGGER.warn(ERROR_PARSING_MSG, e);
        } catch (IOException e) {
            LOGGER.warn(ERROR_PARSING_MSG, e);
        } catch (ParserConfigurationException e) {
            LOGGER.warn(ERROR_PARSING_MSG, e);
        }
        if (geo != null) {
            WKTWriter wktWriter = new WKTWriter();
            return wktWriter.write(geo);
        }
        return null;
    }

}