/**
* Redistribution and use of this software and associated documentation
* ("Software"), with or without modification, are permitted provided
* that the following conditions are met:
*
* 1. Redistributions of source code must retain copyright
* statements and notices. Redistributions must also contain a
* copy of this document.
*
* 2. Redistributions in binary form must reproduce the
* above copyright notice, this list of conditions and the
* following disclaimer in the documentation and/or other
* materials provided with the distribution.
*
* 3. The name "Exolab" must not be used to endorse or promote
* products derived from this Software without prior written
* permission of Intalio, Inc. For written permission,
* please contact info@exolab.org.
*
* 4. Products derived from this Software may not be called "Exolab"
* nor may "Exolab" appear in their names without prior written
* permission of Intalio, Inc. Exolab is a registered
* trademark of Intalio, Inc.
*
* 5. Due credit should be given to the Exolab Project
* (http://www.exolab.org/).
*
* THIS SOFTWARE IS PROVIDED BY INTALIO, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
* NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
* INTALIO, INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*
* Copyright 1999 (C) Intalio, Inc. All Rights Reserved.
*
* $Id: MaxKeyGenerator.java,v 1.4 2004/03/25 12:30:18 wguttmann Exp $
*/
package org.exolab.castor.jdo.drivers;
import java.math.BigDecimal;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Types;
import java.util.Properties;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.exolab.castor.jdo.PersistenceException;
import org.exolab.castor.mapping.MappingException;
import org.exolab.castor.persist.spi.KeyGenerator;
import org.exolab.castor.persist.spi.PersistenceFactory;
import org.exolab.castor.persist.spi.QueryExpression;
import org.exolab.castor.util.Messages;
/**
* MAX key generator.
* @author <a href="on@ibis.odessa.ua">Oleg Nitz</a>
* @author <a href="leonardo@itera.com.br">Leonardo Souza Mario Bueno</a>
* @version $Revision: 1.4 $ $Date: 2004/03/25 12:30:18 $
* @see MaxKeyGeneratorFactory
*/
public final class MaxKeyGenerator implements KeyGenerator
{
/**
* The <a href="http://jakarta.apache.org/commons/logging/">Jakarta
* Commons Logging</a> instance used for all logging.
*/
private static Log _log = LogFactory.getFactory().getInstance(MaxKeyGenerator.class);
private static final BigDecimal ONE = new BigDecimal( 1 );
private final int _sqlType;
private final PersistenceFactory _factory;
/**
* Initialize the MAX key generator.
*/
public MaxKeyGenerator( PersistenceFactory factory, int sqlType )
throws MappingException
{
_factory = factory;
_sqlType = sqlType;
if ( sqlType != Types.INTEGER && sqlType != Types.NUMERIC && sqlType != Types.DECIMAL && sqlType != Types.BIGINT)
throw new MappingException( Messages.format( "mapping.keyGenSQLType",
getClass().getName(), new Integer( sqlType ) ) );
}
/**
* Generate a new key for the specified table as "MAX(primary_key) + 1".
*
* If there is no records in the table, then the value 1 is returned.
*
* @param conn An open connection within the given transaction
* @param tableName The table name
* @param primKeyName The primary key name
* @param props A temporary replacement for Principal object
* @return A new key
* @throws PersistenceException An error occured talking to persistent
* storage
*/
public Object generateKey( Connection conn, String tableName, String primKeyName,
Properties props )
throws PersistenceException
{
String sql;
PreparedStatement stmt = null;
ResultSet rs;
QueryExpression query;
Object identity = null;
try {
query = _factory.getQueryExpression();
if ( _factory.getFactoryName().equals( "mysql" ) ) {
// Create SQL sentence of the form
// "SELECT MAX(pk) FROM table"
query.addSelect("MAX(" + _factory.quoteName(primKeyName)+ ")");
query.addTable(tableName);
// SELECT without lock
sql = query.getStatement( false );
} else {
// Create SQL sentence of the form
// "SELECT pk FROM table WHERE pk=(SELECT MAX(t1.pk) FROM table t1)"
// with database-dependent keyword for lock
query.addColumn( tableName, primKeyName);
query.addCondition( tableName, primKeyName, QueryExpression.OpEquals,
"(SELECT MAX(t1." + _factory.quoteName(primKeyName) + ") FROM " + _factory.quoteName(tableName) + " t1)");
// SELECT and put lock on the last record
sql = query.getStatement( true );
}
stmt = conn.prepareStatement(sql);
rs = stmt.executeQuery();
if ( rs.next() ) {
if ( _sqlType == Types.INTEGER )
identity = new Integer( rs.getInt( 1 ) + 1 );
else if ( _sqlType == Types.BIGINT )
identity = new Long( rs.getLong( 1 ) + 1 );
else {
BigDecimal max = rs.getBigDecimal( 1 );
if (max == null) {
identity = ONE;
} else {
identity = max.add( ONE );
}
}
} else {
if ( _sqlType == Types.INTEGER )
identity = new Integer( 1 );
else if ( _sqlType == Types.BIGINT )
identity = new Long( 1 );
else
identity = ONE;
}
} catch ( SQLException ex ) {
throw new PersistenceException( Messages.format(
"persist.keyGenSQL", ex.toString() ), ex );
} finally {
if ( stmt != null ) {
try {
stmt.close();
} catch ( SQLException ex ) {
_log.warn (Messages.message ("persist.stClosingFailed"), ex);
}
}
}
if (identity == null) {
throw new PersistenceException( Messages.format(
"persist.keyGenOverflow", getClass().getName() ) );
}
return identity;
}
/**
* Style of key generator: BEFORE_INSERT, DURING_INSERT or AFTER_INSERT ?
*/
public final byte getStyle() {
return BEFORE_INSERT;
}
/**
* Gives a possibility to patch the Castor-generated SQL statement
* for INSERT (makes sense for DURING_INSERT key generators)
*/
public final String patchSQL( String insert, String primKeyName )
throws MappingException {
return insert;
}
/**
* Is key generated in the same connection as INSERT?
*/
public boolean isInSameConnection() {
return true;
}
}