de.lemo.dms.db.hibernate.HibernateDBHandler.java Source code

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Here is the source code for de.lemo.dms.db.hibernate.HibernateDBHandler.java

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/**
 * File ./src/main/java/de/lemo/dms/db/hibernate/HibernateDBHandler.java
 * Lemo-Data-Management-Server for learning analytics.
 * Copyright (C) 2013
 * Leonard Kappe, Andreas Pursian, Sebastian Schwarzrock, Boris Wenzlaff
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * any later version.
 * 
 * This program 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 General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
**/

/**
 * File ./main/java/de/lemo/dms/db/hibernate/HibernateDBHandler.java
 * Date 2013-01-24
 * Project Lemo Learning Analytics
 */

package de.lemo.dms.db.hibernate;

import java.util.Collection;
import java.util.List;
import org.apache.log4j.Logger;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.Transaction;
import de.lemo.dms.db.EQueryType;
import de.lemo.dms.db.IDBHandler;

/**
 * Implementation of the IDBHandler interface for Hibernate.
 * 
 * @author s.schwarzrock
 */
public class HibernateDBHandler implements IDBHandler {

    private static final int BATCH_SIZE = 50;

    private final Logger logger = Logger.getLogger(this.getClass());

    @Override
    public Session getMiningSession() {
        return MiningHibernateUtil.getSessionFactory().openSession();
    }

    /**
     * Saves a list of generic objects to the database.
     */
    @Override
    public void saveCollectionToDB(final Session session, final List<Collection<?>> data) {

        try {
            int classOb = 0;
            String className = "";
            Transaction tx = session.beginTransaction();
            int i = 0;
            for (int j = 0; j < data.size(); j++) {
                for (final Object obj : data.get(j)) {

                    if (!className.equals("") && !className.equals(obj.getClass().getName())) {
                        this.logger.info("Wrote " + classOb + " objects of class " + className);
                        classOb = 0;
                    }
                    className = obj.getClass().getName();
                    i++;
                    classOb++;
                    session.saveOrUpdate(obj);
                    if ((i % HibernateDBHandler.BATCH_SIZE) == 0) {
                        // flush a batch of inserts and release memory:
                        session.flush();
                        session.clear();
                    }
                }
            }
            this.logger.info("Wrote " + classOb + " objects of class " + className + " to database.");
            session.flush();
            tx.commit();
            session.clear();
            //this.closeSession(session);
        } catch (final HibernateException e) {
            logger.error(e.getMessage());
        }
    }

    /**
     * Save a single object to the database.
     */
    @Override
    public void saveToDB(final Session session, final Object data) {
        final Transaction tx = session.beginTransaction();
        session.saveOrUpdate(data);
        tx.commit();
        session.clear();
    }

    /**
     * Closes the database connection.
     */
    @Override
    public void closeSession(final Session session) {
        try {
            session.clear();
            session.close();
        } catch (final HibernateException he) {
            logger.error(he.getMessage());
        }
    }

    /**
     * Performs a Hibernate query.
     */
    @Override
    public List<?> performQuery(final Session session, final EQueryType queryType, final String query) {
        try {
            switch (queryType) {
            case HQL:
                return session.createQuery(query).list();
            case SQL:
                return session.createSQLQuery(query).list();
            default:
                break;
            }
        } catch (final HibernateException he) {
            logger.error(he.getMessage());
        }
        return null;
    }

}