FeatureUtil.java

package au.gov.amsa.geo.projection;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

import org.apache.commons.io.IOUtils;
import org.geotools.geometry.jts.JTS;
import org.geotools.referencing.CRS;
import org.opengis.geometry.MismatchedDimensionException;
import org.opengis.referencing.FactoryException;
import org.opengis.referencing.NoSuchAuthorityCodeException;
import org.opengis.referencing.crs.CoordinateReferenceSystem;
import org.opengis.referencing.operation.MathTransform;
import org.opengis.referencing.operation.TransformException;

import au.gov.amsa.geo.model.Position;

import com.vividsolutions.jts.geom.Coordinate;
import com.vividsolutions.jts.geom.GeometryFactory;
import com.vividsolutions.jts.geom.Point;

public class FeatureUtil {
	public static final String EPSG_4326 = "EPSG:4326";
	public static final String EPSG_900913 = "EPSG:900913";
	public static final String EPSG_3857 = "EPSG:3857";
	/**
	 * ARCGIS copy of 3857
	 */
	public static final String EPSG_102100 = "EPSG:102100";

	private static Map<String, CoordinateReferenceSystem> crs = new HashMap<String, CoordinateReferenceSystem>();

	public static synchronized CoordinateReferenceSystem getCrs(String epsg) {
		try {
			if (crs.get(epsg) != null)
				return crs.get(epsg);

			if (epsg.equals(EPSG_900913)) {
				String wkt = IOUtils.toString(FeatureUtil.class
				        .getResourceAsStream("/epsg/EPSG_900913.txt"));
				crs.put(epsg, CRS.parseWKT(wkt));
			} else if (epsg.equals(EPSG_102100)) {
				String wkt = IOUtils.toString(FeatureUtil.class
				        .getResourceAsStream("/epsg/EPSG_102100.txt"));
				crs.put(epsg, CRS.parseWKT(wkt));
			} else if (epsg.equals(EPSG_3857)) {
				String wkt = IOUtils.toString(FeatureUtil.class
				        .getResourceAsStream("/epsg/EPSG_3857.txt"));
				crs.put(epsg, CRS.parseWKT(wkt));
			} else
				crs.put(epsg, CRS.decode(epsg, true));
			return crs.get(epsg);
		} catch (FactoryException e) {
			throw new RuntimeException("could not load " + epsg, e);
		} catch (IOException e) {
			throw new RuntimeException(e);
		}
	}

	public static Point createPoint(double lat, double lon, String srsName) {
		GeometryFactory geometryFactory = new GeometryFactory();
		Coordinate coordinate = new Coordinate(lon, lat);
		Point point = geometryFactory.createPoint(coordinate);

		try {
			if (!srsName.equals(EPSG_4326)) {
				MathTransform transform = CRS.findMathTransform(getCrs(EPSG_4326), getCrs(srsName));
				point = (Point) JTS.transform(point, transform);
			}
			return point;

		} catch (NoSuchAuthorityCodeException e) {
			throw new RuntimeException(e);
		} catch (FactoryException e) {
			throw new RuntimeException(e);
		} catch (MismatchedDimensionException e) {
			throw new RuntimeException(e);
		} catch (TransformException e) {
			throw new RuntimeException(e);
		}
	}

	public static Position convertToLatLon(double x, double y, String srsName) {
		GeometryFactory geometryFactory = new GeometryFactory();
		Coordinate coordinate = new Coordinate(x, y);
		Point point = geometryFactory.createPoint(coordinate);

		try {
			if (!srsName.equals(EPSG_4326)) {
				MathTransform transform = CRS.findMathTransform(getCrs(EPSG_4326), getCrs(srsName));
				point = (Point) JTS.transform(point, transform.inverse());
			}
			return new Position(point.getY(), point.getX());
		} catch (NoSuchAuthorityCodeException e) {
			throw new RuntimeException(e);
		} catch (FactoryException e) {
			throw new RuntimeException(e);
		} catch (MismatchedDimensionException e) {
			throw new RuntimeException(e);
		} catch (TransformException e) {
			throw new RuntimeException(e);
		}
	}

}