Application: gvSIG desktop

package org.gvsig.fmap.dal.feature.impl;

import java.util.HashMap;

import java.util.Iterator;

import java.util.Map;

import org.gvsig.fmap.dal.DALLocator;

import org.gvsig.fmap.dal.exception.DataException;

import org.gvsig.fmap.dal.feature.AbstractFeatureStoreTransform;

import org.gvsig.fmap.dal.feature.EditableFeature;

import org.gvsig.fmap.dal.feature.EditableFeatureType;

import org.gvsig.fmap.dal.feature.Feature;

import org.gvsig.fmap.dal.feature.FeatureAttributeDescriptor;

import org.gvsig.fmap.dal.feature.FeatureQuery;

import org.gvsig.fmap.dal.feature.FeatureSet;

import org.gvsig.fmap.dal.feature.FeatureStore;

import org.gvsig.tools.evaluator.Evaluator;

import org.gvsig.tools.persistence.PersistenceException;

import org.gvsig.tools.persistence.PersistentState;

public class JoinTransform extends AbstractFeatureStoreTransform {

        /**

         * Store whose default feature type will be transformed

         */

        private FeatureStore store1;

        /**

         * Store from which the join transform will get the additional attributes

         */

        private FeatureStore store2;

        /**

         * name of the key attr in store1 that will be used to match features in

         * store2

         */

        private String keyAttr1;

        /**

         * name of the key attr in store2 that will be used to match features in

         * store1

         */

        private String keyAttr2;

        /**

         * names of the attributes to join from store2 to store1

         */

        private String[] attrs;

        /**

         * Attribute names may change after transformation if they are repeated in

         * both stores. This map keeps correspondence between store2 original names

         * and their transformed counterparts.

         */

        private Map targetNamesMap;

        /**

         * A default constructor

         */

        public JoinTransform() {

                targetNamesMap = new HashMap();

        }

        /**

         * Initializes all the necessary data for this transform

         *

         * @param store1

         *            store whose default feature type is the target of this

         *            transform

         *

         * @param store2

         *            store whose default feature type will provide the new

         *            attributes to join

         *

         * @param keyAttr1

         *            key attribute in store1 that matches keyAttr2 in store2

         *            (foreign key), used for joining both stores.

         *

         * @param keyAttr2

         *            key attribute in store2 that matches keyAttr1 in store2

         *            (foreign key), used for joining both stores.

         *

         * @param attrs

         *            names of the attributes in store2 that will be joined to

         *            store1.

         */

        public void initialize(FeatureStore store1, FeatureStore store2,

                        String keyAttr1, String keyAttr2, String[] attrs)

                        throws DataException {

                // Initialize needed data

                this.store1 = store1;

                this.store2 = store2;

                this.keyAttr1 = keyAttr1;

                this.keyAttr2 = keyAttr2;

                this.attrs = attrs;

                // calculate this transform resulting feature type

                // by adding all specified attrs from store2 to store1's default

                // feature type

                EditableFeatureType type = this.store1.getDefaultFeatureType().getEditable();

                for (int i = 0; i < attrs.length; i++) {

                        String name = attrs[i];

                        // If an attribute already exists with the same name in store1's

                        // default feature type,

                        // calculate an alternate name and add it to our type

                        int j = 0;

                        while (type.get(name) != null) {

                                name = attrs[i] + "_" + ++j;

                        }

                        type.add(name, store2.getDefaultFeatureType()

                                        .getAttributeDescriptor(attrs[i]).getDataType());

                        // keep correspondence between original name and transformed name

                        this.targetNamesMap.put(attrs[i], name);

                }

                // assign calculated feature type as this transform's feature type

                setDefaultFeatureType(type.getNotEditableCopy());

        }

        /**

         *

         *

         * @param source

         *

         * @param target

         *

         * @throws DataException

         */

        public void applyTransform(Feature source, EditableFeature target)

                        throws DataException {

                // copy the data from store1 into the resulting feature

                target.copyFrom(source);

                // ask store2 for the specified attributes, filtering by the key

                // attribute value

                // from the source feature

                Evaluator eval = DALLocator.getDataManager().createExpresion(

                                keyAttr2 + "=" + source.get(keyAttr1));

                FeatureQuery query = new FeatureQuery(attrs, eval);

                FeatureSet set = store2.getFeatureSet(query);

                // In this join implementation, we will take only the first matching

                // feature found in store2

                Iterator it = set.iterator();

                if (it.hasNext()) {

                        Feature feat = (Feature) it.next();

                        // copy all attributes from joined feature to target

                        Iterator it2 = feat.getType().iterator();

                        while (it2.hasNext()) {

                                FeatureAttributeDescriptor attr = (FeatureAttributeDescriptor) it2

                                                .next();

                                // find original attribute name

                                String targetName = (String) this.targetNamesMap.get(attr

                                                .getName());

                                // copy its value to target feature attribute

                                target.set(targetName, feat.get(attr.getName()));

                        }

                }

                set.dispose();

        }

        public void loadState(PersistentState state) throws PersistenceException {

                // TODO Auto-generated method stub

        }

        public void setState(PersistentState state) throws PersistenceException {

                // TODO Auto-generated method stub

        }

}