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Hibernate example source code file (IteratorImpl.java)

This example Hibernate source code file (IteratorImpl.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Hibernate tags/keywords

entitytype, eventsource, hibernateexception, iteratorimpl, jdbc, not, object, object, preparedstatement, resultset, sql, sqlexception, sqlexception, string, type, unsupportedoperationexception, util

The Hibernate IteratorImpl.java source code

/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2008, Red Hat Middleware LLC or third-party contributors as
 * indicated by the @author tags or express copyright attribution
 * statements applied by the authors.  All third-party contributions are
 * distributed under license by Red Hat Middleware LLC.
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * 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 Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 *
 */
package org.hibernate.internal;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.NoSuchElementException;
import org.hibernate.HibernateException;
import org.hibernate.JDBCException;
import org.hibernate.engine.HibernateIterator;
import org.hibernate.event.spi.EventSource;
import org.hibernate.hql.internal.HolderInstantiator;
import org.hibernate.type.EntityType;
import org.hibernate.type.Type;
import org.jboss.logging.Logger;

/**
 * An implementation of <tt>java.util.Iterator that is
 * returned by <tt>iterate() query execution methods.
 * @author Gavin King
 */
public final class IteratorImpl implements HibernateIterator {

    private static final CoreMessageLogger LOG = Logger.getMessageLogger(CoreMessageLogger.class, IteratorImpl.class.getName());

	private ResultSet rs;
	private final EventSource session;
	private boolean readOnly;
	private final Type[] types;
	private final boolean single;
	private Object currentResult;
	private boolean hasNext;
	private final String[][] names;
	private PreparedStatement ps;
	private HolderInstantiator holderInstantiator;

	public IteratorImpl(
	        ResultSet rs,
	        PreparedStatement ps,
	        EventSource sess,
	        boolean readOnly,
	        Type[] types,
	        String[][] columnNames,
	        HolderInstantiator holderInstantiator)
	throws HibernateException, SQLException {

		this.rs=rs;
		this.ps=ps;
		this.session = sess;
		this.readOnly = readOnly;
		this.types = types;
		this.names = columnNames;
		this.holderInstantiator = holderInstantiator;

		single = types.length==1;

		postNext();
	}

	public void close() throws JDBCException {
		if (ps!=null) {
			try {
                LOG.debugf("Closing iterator");
				ps.close();
				ps = null;
				rs = null;
				hasNext = false;
			}
			catch (SQLException e) {
                LOG.unableToCloseIterator(e);
				throw session.getFactory().getSQLExceptionHelper().convert(
				        e,
				        "Unable to close iterator"
					);
			}
			finally {
				try {
					session.getPersistenceContext().getLoadContexts().cleanup( rs );
				}
				catch( Throwable ignore ) {
					// ignore this error for now
                    LOG.debugf("Exception trying to cleanup load context : %s", ignore.getMessage());
				}
			}
		}
	}

	private void postNext() throws SQLException {
        LOG.debugf("Attempting to retrieve next results");
		this.hasNext = rs.next();
		if (!hasNext) {
            LOG.debugf("Exhausted results");
			close();
        } else LOG.debugf("Retrieved next results");
	}

	public boolean hasNext() {
		return hasNext;
	}

	public Object next() throws HibernateException {
		if ( !hasNext ) throw new NoSuchElementException("No more results");
		boolean sessionDefaultReadOnlyOrig = session.isDefaultReadOnly();
		session.setDefaultReadOnly( readOnly );
		try {
			boolean isHolder = holderInstantiator.isRequired();

            LOG.debugf("Assembling results");
			if ( single && !isHolder ) {
				currentResult = types[0].nullSafeGet( rs, names[0], session, null );
			}
			else {
				Object[] currentResults = new Object[types.length];
				for (int i=0; i<types.length; i++) {
					currentResults[i] = types[i].nullSafeGet( rs, names[i], session, null );
				}

				if (isHolder) {
					currentResult = holderInstantiator.instantiate(currentResults);
				}
				else {
					currentResult = currentResults;
				}
			}

			postNext();
            LOG.debugf("Returning current results");
			return currentResult;
		}
		catch (SQLException sqle) {
			throw session.getFactory().getSQLExceptionHelper().convert(
					sqle,
					"could not get next iterator result"
				);
		}
		finally {
			session.setDefaultReadOnly( sessionDefaultReadOnlyOrig );
		}
	}

	public void remove() {
		if (!single) {
			throw new UnsupportedOperationException("Not a single column hibernate query result set");
		}
		if (currentResult==null) {
			throw new IllegalStateException("Called Iterator.remove() before next()");
		}
		if ( !( types[0] instanceof EntityType ) ) {
			throw new UnsupportedOperationException("Not an entity");
		}

		session.delete(
				( (EntityType) types[0] ).getAssociatedEntityName(),
				currentResult,
				false,
		        null
			);
	}
}

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