Subversion Repositories hibernate-spatial

/*

 * $Id: FeatureAdapter.java 165 2010-03-11 20:27:08Z maesenka $

 *

 * This file is part of Hibernate Spatial, an extension to the

 * hibernate ORM solution for geographic data.

 *

 * Copyright © 2007-2010 Geovise BVBA

 *

 * 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; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * 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.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this library; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 *

 * For more information, visit: http://www.hibernatespatial.org/

 */

package org.hibernatespatial.readers;

import org.hibernate.EntityMode;

import org.hibernate.metadata.ClassMetadata;

import org.hibernate.property.Getter;

import org.hibernate.util.ReflectHelper;

import org.hibernatespatial.helper.FinderException;

import org.hibernatespatial.helper.GeometryPropertyFinder;

import java.lang.reflect.InvocationHandler;

import java.lang.reflect.Method;

import java.lang.reflect.Proxy;

/**

 * Adapts arbitrary objects to the {@link Feature} interface using dynamic proxying.

 *

 * @author Karel Maesen

 */

public class FeatureAdapter {

    public static Feature adapt(Object o, ClassMetadata cf) {

        return (Feature) Proxy.newProxyInstance(o.getClass().getClassLoader(),

                new Class[]{Feature.class},

                new FeatureInvocationHandler(o, cf));

    }

    static private class FeatureInvocationHandler implements InvocationHandler {

        private final Object target;

        private final ClassMetadata metadata;

        private Method targetGeomGetter;

        private Method targetIdGetter;

        private static final Method geomGetter;

        private static final Method idGetter;

        private static final Method attrGetter;

        private static GeometryPropertyFinder geomPropertyFinder = new GeometryPropertyFinder();

        static {

            Class featureIntf = Feature.class;

            try {

                geomGetter = featureIntf.getDeclaredMethod("getGeometry", new Class[]{});

                idGetter = featureIntf.getDeclaredMethod("getId", new Class[]{});

                attrGetter = featureIntf.getDeclaredMethod("getAttribute", new Class[]{String.class});

            } catch (Exception e) {

                throw new RuntimeException("Probable programming Error", e);

            }

        }

        private FeatureInvocationHandler(Object o, ClassMetadata meta) {

            //TODO check if this is sufficiently general. What if not a POJO?

            if (meta.getMappedClass(EntityMode.POJO) != o.getClass()) {

                throw new RuntimeException("Metadata and POJO class do not cohere");

            }

            this.target = o;

            this.metadata = meta;

        }

        public Object invoke(Object proxy, Method method, Object[] args)

                throws Throwable {

            Method m = getTargetGetter(method, args);

            if (m == null) {

                return method.invoke(this.target, args);

            } else {

                return m.invoke(this.target);

            }

        }

        private Method getTargetGetter(Method invokedMethod, Object[] args) {

            try {

                if (invokedMethod.equals(geomGetter)) {

                    if (this.targetGeomGetter == null) {

                        this.targetGeomGetter = getGeomGetter();

                    }

                    return this.targetGeomGetter;

                } else if (invokedMethod.equals(idGetter)) {

                    if (this.targetIdGetter == null) {

                        this.targetIdGetter = getIdGetter();

                    }

                    return this.targetIdGetter;

                } else if (invokedMethod.equals(attrGetter)) {

                    String property = (String) args[0];

                    return getGetterFor(property);

                } else {

                    return null;

                }

            } catch (Exception e) {

                throw new RuntimeException("Problem getting suitable target method for method:  " + invokedMethod.getName(), e);

            }

        }

        private Method getGetterFor(String property) {

            Class cl = this.metadata.getMappedClass(EntityMode.POJO);

            Getter getter = ReflectHelper.getGetter(cl, property);

            return getter.getMethod();

        }

        private Method getGeomGetter() {

            try {

                String prop = getGeometryPropertyName();

                return getGetterFor(prop);

            } catch (Exception e) {

                throw new RuntimeException(e);

            }

        }

        public String getGeometryPropertyName() throws FinderException {

            return this.geomPropertyFinder.find(this.metadata);

        }

        public Method getIdGetter() {

            String prop = this.metadata.getIdentifierPropertyName();

            return getGetterFor(prop);

        }

    }

}