org.hibernate.search.query.fieldcache.impl.MultiStringFieldLoadingStrategy.java Source code

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Here is the source code for org.hibernate.search.query.fieldcache.impl.MultiStringFieldLoadingStrategy.java

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/*
 * Hibernate Search, full-text search for your domain model
 *
 * License: GNU Lesser General Public License (LGPL), version 2.1 or later
 * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
 */

package org.hibernate.search.query.fieldcache.impl;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.apache.lucene.index.AtomicReaderContext;
import org.apache.lucene.index.SortedSetDocValues;
import org.apache.lucene.search.FieldCache;
import org.apache.lucene.util.BytesRef;

/**
 * A {@code FieldLoadingStrategy} which uses {@link SortedSetDocValues} to load fields with multiple values.
 *
 * @author Hardy Ferentschik
 */
public final class MultiStringFieldLoadingStrategy implements FieldLoadingStrategy {

    private final String fieldName;
    private SortedSetDocValues sortedSetDocValues;

    public MultiStringFieldLoadingStrategy(String fieldName) {
        this.fieldName = fieldName;
    }

    @Override
    public void loadNewCacheValues(AtomicReaderContext context) throws IOException {
        // FieldCache.getDocTermOrd allows to get all terms for a given multi value field per document. SortedSetDocValues
        // allows to retrieve the term values via iterator like API
        // See also https://issues.apache.org/jira/browse/LUCENE-3354
        sortedSetDocValues = FieldCache.DEFAULT.getDocTermOrds(context.reader(), fieldName);
    }

    @Override
    public String[] collect(int relativeDocId) {
        // use the loaded SortedSetDocValues to retrieve all values for the field
        sortedSetDocValues.setDocument(relativeDocId);
        List<String> values = new ArrayList<String>();

        long ordinal = sortedSetDocValues.nextOrd();
        while (ordinal != SortedSetDocValues.NO_MORE_ORDS) {
            BytesRef bytesRef = sortedSetDocValues.lookupOrd(ordinal);
            sortedSetDocValues.lookupOrd(ordinal);
            values.add(bytesRef.utf8ToString());
            ordinal = sortedSetDocValues.nextOrd();
        }

        return values.toArray(new String[values.size()]);
    }

}