/*
* GeoTools - The Open Source Java GIS Toolkit
* http://geotools.org
*
* (C) 2004-2008, Open Source Geospatial Foundation (OSGeo)
*
* This library 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;
* version 2.1 of the License.
*
* This library 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.
*/
package org.geotools.geometry.jts;
import java.lang.reflect.Array;
import java.util.Arrays;
import java.util.Set;
import com.vividsolutions.jts.geom.CoordinateSequenceFactory;
import com.vividsolutions.jts.geom.GeometryFactory;
import com.vividsolutions.jts.geom.PrecisionModel;
import org.geotools.factory.Hints;
import org.geotools.factory.FactoryFinder;
import org.geotools.factory.FactoryCreator;
import org.geotools.factory.FactoryRegistry;
import org.geotools.factory.FactoryRegistryException;
import org.geotools.resources.LazySet;
/**
* Defines static methods used to access {@linkplain GeometryFactory geometry},
* {@linkplain CoordinateSequenceFactory coordinate sequence} or
* {@linkplain PrecisionModel precision model} factories.
*
*
*
* @source $URL$
* @version $Id$
* @author Martin Desruisseaux
*/
public class JTSFactoryFinder extends FactoryFinder {
/**
* The service registry for this manager.
* Will be initialized only when first needed.
*/
private static FactoryRegistry registry;
/**
* Do not allows any instantiation of this class.
*/
private JTSFactoryFinder() {
// singleton
}
/**
* Returns the service registry. The registry will be created the first
* time this method is invoked.
*/
private static FactoryRegistry getServiceRegistry() {
assert Thread.holdsLock(JTSFactoryFinder.class);
if (registry == null) {
registry = new FactoryCreator(Arrays.asList(new Class<?>[] { GeometryFactory.class } ));
registry.registerServiceProvider( new GeometryFactory(), GeometryFactory.class );
}
return registry;
}
/**
* Returns the first implementation of {@link GeometryFactory} matching the specified hints.
* If no implementation matches, a new one is created if possible or an exception is thrown
* otherwise.
* <p>
* Hints that may be understood includes
* {@link Hints#JTS_COORDINATE_SEQUENCE_FACTORY JTS_COORDINATE_SEQUENCE_FACTORY},
* {@link Hints#JTS_PRECISION_MODEL JTS_PRECISION_MODEL} and
* {@link Hints#JTS_SRID JTS_SRID}.
*
* @param hints An optional map of hints, or {@code null} if none.
* @return The first geometry factory that matches the supplied hints.
* @throws FactoryRegistryException if no implementation was found or can be created for the
* {@link GeometryFactory} category and the given hints.
*/
public static synchronized GeometryFactory getGeometryFactory(Hints hints) throws FactoryRegistryException {
hints = mergeSystemHints(hints);
return (GeometryFactory) getServiceRegistry().getServiceProvider(
GeometryFactory.class, null, hints, Hints.JTS_GEOMETRY_FACTORY);
}
/**
* Returns the first implementation of {@link GeometryFactory}, a new one is created if
* possible or an exception is thrown otherwise.
*
* @return The first geometry factory available on the classpath
* @throws FactoryRegistryException if no implementation was found or can be created for the
* {@link GeometryFactory} category.
*/
public static synchronized GeometryFactory getGeometryFactory() throws FactoryRegistryException {
return getGeometryFactory(null);
}
/**
* Returns a set of all available implementations for the {@link GeometryFactory} category.
*
* @return Set of available geometry factory implementations.
*/
public static synchronized Set getGeometryFactories() {
return new LazySet(getServiceRegistry().getServiceProviders(GeometryFactory.class, null, null));
}
/**
* Returns the first implementation of {@link PrecisionModel} matching the specified hints.
* If no implementation matches, a new one is created if possible or an exception is thrown
* otherwise.
*
* @param hints An optional map of hints, or {@code null} if none.
* @return The first precision model that matches the supplied hints.
* @throws FactoryRegistryException if no implementation was found or can be created for the
* {@link PrecisionModel} category and the given hints.
*/
public static synchronized PrecisionModel getPrecisionModel(Hints hints) throws FactoryRegistryException {
hints = mergeSystemHints(hints);
return (PrecisionModel) getServiceRegistry().getServiceProvider(
PrecisionModel.class, null, hints, Hints.JTS_PRECISION_MODEL);
}
/**
* Returns a set of all available implementations for the {@link PrecisionModel} category.
*
* @return Set of available precision model implementations.
*/
public static synchronized Set getPrecisionModels() {
return new LazySet(getServiceRegistry().getServiceProviders(PrecisionModel.class, null, null));
}
/**
* Returns the first implementation of {@link CoordinateSequenceFactory} matching the specified
* hints. If no implementation matches, a new one is created if possible or an exception is
* thrown otherwise.
*
* @param hints An optional map of hints, or {@code null} if none.
* @return The first coordinate sequence factory that matches the supplied hints.
* @throws FactoryRegistryException if no implementation was found or can be created for the
* {@link CoordinateSequenceFactory} interface and the given hints.
*/
public static synchronized CoordinateSequenceFactory getCoordinateSequenceFactory(Hints hints) throws FactoryRegistryException {
hints = mergeSystemHints(hints);
return (CoordinateSequenceFactory) getServiceRegistry().getServiceProvider(
CoordinateSequenceFactory.class, null, hints, Hints.JTS_COORDINATE_SEQUENCE_FACTORY);
}
/**
* Returns a set of all available implementations for the {@link CoordinateSequenceFactory}
* interface.
*
* @return Set of available coordinate sequence factory implementations.
*/
public static synchronized Set getCoordinateSequenceFactories() {
return new LazySet(getServiceRegistry().getServiceProviders(CoordinateSequenceFactory.class, null, null));
}
/**
* Scans for factory plug-ins on the application class path. This method is
* needed because the application class path can theoretically change, or
* additional plug-ins may become available. Rather than re-scanning the
* classpath on every invocation of the API, the class path is scanned
* automatically only on the first invocation. Clients can call this
* method to prompt a re-scan. Thus this method need only be invoked by
* sophisticated applications which dynamically make new plug-ins
* available at runtime.
*/
public static void scanForPlugins() {
if (registry != null) {
registry.scanForPlugins();
}
}
/**
* A custom registry for JTS factories. There is usually no need for custom implementation of
* {@link ServiceRegistry} for geotools object. However, JTS factories are an other story
* because they don't know anything about the Geotools's factory plugin system. Consequently
* we need to process JTS factories in a special way.
*/
private static final class Registry extends FactoryCreator {
/**
* Creates a registry for JTS factories.
*/
public Registry() {
super(Arrays.asList(new Class<?>[] {
GeometryFactory.class,
PrecisionModel.class,
CoordinateSequenceFactory.class}));
}
/**
* Creates a new instance of the specified factory using the specified hints.
*
* @param category The category to instantiate.
* @param implementation The factory class to instantiate.
* @param hints The implementation hints.
* @return The factory.
* @throws FactoryRegistryException if the factory creation failed.
*/
protected Object createServiceProvider(final Class category,
final Class implementation,
final Hints hints)
throws FactoryRegistryException
{
if (GeometryFactory.class.isAssignableFrom(category) &&
GeometryFactory.class.equals(implementation))
{
return new GeometryFactory(getPrecisionModel(hints), getSRID(hints),
getCoordinateSequenceFactory(hints));
}
return super.createServiceProvider(category, implementation, hints);
}
/**
* Extracts the SRID from the hints, or returns {@code 0} if none.
*/
private static int getSRID(final Hints hints) {
if (hints != null) {
final Integer SRID = (Integer) hints.get(Hints.JTS_SRID);
if (SRID != null) {
return SRID.intValue();
}
}
return 0;
}
/**
* Returns {@code true} if the specified {@code provider} meets the requirements specified
* by a map of {@code hints}. This method is invoked automatically when the {@code provider}
* is known to meets standard Geotools requirements.
* <p>
* This implementation add JTS-specific checks. More specifically, we checks if
* {@link GeometryFactory} uses the required {@link CoordinateSequenceFactory}
* and {@link PrecisionModel}.
*
* @param provider The provider to checks.
* @param category The factory's category.
* @param hints The user requirements.
* @return {@code true} if the {@code provider} meets the user requirements.
*/
protected boolean isAcceptable(final Object provider, final Class category, final Hints hints) {
if (GeometryFactory.class.isAssignableFrom(category)) {
final GeometryFactory factory = (GeometryFactory) provider;
final CoordinateSequenceFactory sequence = factory.getCoordinateSequenceFactory();
final PrecisionModel precision = factory.getPrecisionModel();
if (!isAcceptable(sequence, hints.get(Hints.JTS_COORDINATE_SEQUENCE_FACTORY)) ||
!isAcceptable(precision, hints.get(Hints.JTS_PRECISION_MODEL)))
{
return false;
}
final int SRID = getSRID(hints);
if (SRID!=0 && SRID!=factory.getSRID()) {
return false;
}
}
return super.isAcceptable(provider, category, hints);
}
/**
* Checks if an actual {@link GeometryFactory} property matches the given hint.
*
* @param actual The geometry factory property, either a {@link CoordinateSequenceFactory}
* or a {@link PrecisionModel} concrete implementation.
* @param requested The user's hint, either a concrete implementation of the same class
* than {@code actual}, a {@link Class} or an array of them.
* @return {@code true} if the {@code actual} value matches the {@code requested}
* value, or {@code false} otherwise.
*/
private static boolean isAcceptable(final Object actual,
final Object requested)
{
/*
* If the user didn't provided any hint, or if the factory
* already uses the requested object, accepts.
*/
if (requested==null || requested.equals(actual)) {
return true;
}
/*
* If hint is an array (either Class object or concrete
* implementations), iterates over all array's elements.
*/
if (requested.getClass().isArray()) {
final int length = Array.getLength(requested);
for (int i=0; i<length; i++) {
if (!isAcceptable(actual, Array.get(requested, i))) {
return false;
}
}
return true;
}
/*
* If hint is only a class instead of an actual implementation,
* accepts instances of this class or any subclasses.
*/
if (actual!=null && requested instanceof Class) {
return ((Class) requested).isAssignableFrom(actual.getClass());
}
return false;
}
}
}