uit.qabpss.util.dao.orm.hibernate.QueryUtil.java Source code

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Here is the source code for uit.qabpss.util.dao.orm.hibernate.QueryUtil.java

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/**
 * Copyright (c) 2000-2009 Liferay, Inc. All rights reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

package uit.qabpss.util.dao.orm.hibernate;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import org.hibernate.Query;
import org.hibernate.ScrollableResults;
import org.hibernate.dialect.Dialect;
import uit.qabpss.util.Randomizer;
import uit.qabpss.util.log.Log;
import uit.qabpss.util.log.LogFactoryUtil;

/**
 * <a href="QueryUtil.java.html"><b><i>View Source</i></b></a>
 *
 * @author Brian Wing Shun Chan
 *
 */
public class QueryUtil {

    public static final int ALL_POS = -1;

    public static Iterator<?> iterate(Query query, int start, int end) {

        return iterate(query, start, end, true);
    }

    public static Iterator<?> iterate(Query query, int start, int end, boolean unmodifiable) {

        return list(query, start, end).iterator();
    }

    public static List<?> list(Query query, int start, int end) {

        if ((start == ALL_POS) && (end == ALL_POS)) {
            return query.list();
        } else {

            query.setMaxResults(end - start);
            query.setFirstResult(start);

            return query.list();

        }
    }

    public static List<?> randomList(Query query, Dialect dialect, int total, int num) {

        return randomList(query, dialect, total, num, true);
    }

    public static List<?> randomList(Query query, Dialect dialect, int total, int num, boolean unmodifiable) {

        if ((total == 0) || (num == 0)) {
            return new ArrayList<Object>();
        }

        if (num >= total) {
            return list(query, ALL_POS, ALL_POS);
        }

        int[] scrollIds = Randomizer.getInstance().nextInt(total, num);

        List<Object> list = new ArrayList<Object>();

        ScrollableResults sr = query.scroll();

        for (int i = 0; i < scrollIds.length; i++) {
            if (sr.scroll(scrollIds[i])) {
                Object obj = sr.get(0);

                list.add(obj);

                sr.first();
            }
        }

        return list;

    }

    private static Log _log = LogFactoryUtil.getLog(QueryUtil.class);

}