/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * 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.id;

import java.io.Serializable;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Properties;

import org.hibernate.HibernateException;
import org.hibernate.MappingException;
import org.hibernate.boot.model.naming.ObjectNameNormalizer;
import org.hibernate.engine.jdbc.env.spi.JdbcEnvironment;
import org.hibernate.engine.spi.SharedSessionContractImplementor;
import org.hibernate.internal.CoreLogging;
import org.hibernate.internal.CoreMessageLogger;
import org.hibernate.internal.util.StringHelper;
import org.hibernate.mapping.Table;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.type.Type;

increment

An IdentifierGenerator that returns a long, constructed by counting from the maximum primary key value at startup. Not safe for use in a cluster!

Mapping parameters supported, but not usually needed: tables, column. (The tables parameter specified a comma-separated list of table names.)
Author:Gavin King, Steve Ebersole, Brett Meyer
/** * <b>increment</b><br> * <br> * An <tt>IdentifierGenerator</tt> that returns a <tt>long</tt>, constructed by * counting from the maximum primary key value at startup. Not safe for use in a * cluster!<br> * <br> * Mapping parameters supported, but not usually needed: tables, column. * (The tables parameter specified a comma-separated list of table names.) * * @author Gavin King * @author Steve Ebersole * @author Brett Meyer */
public class IncrementGenerator implements IdentifierGenerator, Configurable { private static final CoreMessageLogger LOG = CoreLogging.messageLogger( IncrementGenerator.class ); private Class returnClass; private String sql; private IntegralDataTypeHolder previousValueHolder; @Override public synchronized Serializable generate(SharedSessionContractImplementor session, Object object) throws HibernateException { if ( sql != null ) { initializePreviousValueHolder( session ); } return previousValueHolder.makeValueThenIncrement(); } @Override public void configure(Type type, Properties params, ServiceRegistry serviceRegistry) throws MappingException { returnClass = type.getReturnedClass(); final JdbcEnvironment jdbcEnvironment = serviceRegistry.getService( JdbcEnvironment.class ); final ObjectNameNormalizer normalizer = (ObjectNameNormalizer) params.get( PersistentIdentifierGenerator.IDENTIFIER_NORMALIZER ); String column = params.getProperty( "column" ); if ( column == null ) { column = params.getProperty( PersistentIdentifierGenerator.PK ); } column = normalizer.normalizeIdentifierQuoting( column ).render( jdbcEnvironment.getDialect() ); String tableList = params.getProperty( "tables" ); if ( tableList == null ) { tableList = params.getProperty( PersistentIdentifierGenerator.TABLES ); } String[] tables = StringHelper.split( ", ", tableList ); final String schema = normalizer.toDatabaseIdentifierText( params.getProperty( PersistentIdentifierGenerator.SCHEMA ) ); final String catalog = normalizer.toDatabaseIdentifierText( params.getProperty( PersistentIdentifierGenerator.CATALOG ) ); StringBuilder buf = new StringBuilder(); for ( int i = 0; i < tables.length; i++ ) { final String tableName = normalizer.toDatabaseIdentifierText( tables[i] ); if ( tables.length > 1 ) { buf.append( "select max(" ).append( column ).append( ") as mx from " ); } buf.append( Table.qualify( catalog, schema, tableName ) ); if ( i < tables.length - 1 ) { buf.append( " union " ); } } if ( tables.length > 1 ) { buf.insert( 0, "( " ).append( " ) ids_" ); column = "ids_.mx"; } sql = "select max(" + column + ") from " + buf.toString(); } private void initializePreviousValueHolder(SharedSessionContractImplementor session) { previousValueHolder = IdentifierGeneratorHelper.getIntegralDataTypeHolder( returnClass ); final boolean debugEnabled = LOG.isDebugEnabled(); if ( debugEnabled ) { LOG.debugf( "Fetching initial value: %s", sql ); } try { PreparedStatement st = session.getJdbcCoordinator().getStatementPreparer().prepareStatement( sql ); try { ResultSet rs = session.getJdbcCoordinator().getResultSetReturn().extract( st ); try { if ( rs.next() ) { previousValueHolder.initialize( rs, 0L ).increment(); } else { previousValueHolder.initialize( 1L ); } sql = null; if ( debugEnabled ) { LOG.debugf( "First free id: %s", previousValueHolder.makeValue() ); } } finally { session.getJdbcCoordinator().getLogicalConnection().getResourceRegistry().release( rs, st ); } } finally { session.getJdbcCoordinator().getLogicalConnection().getResourceRegistry().release( st ); session.getJdbcCoordinator().afterStatementExecution(); } } catch (SQLException sqle) { throw session.getJdbcServices().getSqlExceptionHelper().convert( sqle, "could not fetch initial value for increment generator", sql ); } } }