/*
* 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.dialect.resolver;
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.DatabaseMetaData;
import java.util.Properties;
import org.hibernate.HibernateException;
import org.hibernate.dialect.resolver.DialectResolver;
import org.hibernate.dialect.resolver.DialectResolverSet;
import org.hibernate.dialect.resolver.StandardDialectResolver;
import org.hibernate.dialect.Dialect;
import org.hibernate.cfg.Environment;
import org.hibernate.util.ReflectHelper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* A factory for generating Dialect instances.
*
* @author Steve Ebersole
* @author Tomoto Shimizu Washio
*/
public class DialectFactory {
private static final Logger log = LoggerFactory.getLogger( DialectFactory.class );
private static DialectResolverSet DIALECT_RESOLVERS = new DialectResolverSet();
static {
// register the standard dialect resolver
DIALECT_RESOLVERS.addResolver( new StandardDialectResolver() );
// register resolvers set via Environment property
String userSpecifedResolverSetting = Environment.getProperties().getProperty( Environment.DIALECT_RESOLVERS );
if ( userSpecifedResolverSetting != null ) {
String[] userSpecifedResolvers = userSpecifedResolverSetting.split( "\\s+" );
for ( int i = 0; i < userSpecifedResolvers.length; i++ ) {
registerDialectResolver( userSpecifedResolvers[i] );
}
}
}
/*package*/ static void registerDialectResolver(String resolverName) {
try {
DialectResolver resolver = ( DialectResolver ) ReflectHelper.classForName( resolverName ).newInstance();
DIALECT_RESOLVERS.addResolverAtFirst( resolver );
}
catch ( ClassNotFoundException cnfe ) {
log.warn( "Dialect resolver class not found: " + resolverName );
}
catch ( Exception e ) {
log.warn( "Could not instantiate dialect resolver class", e );
}
}
/**
* Builds an appropriate Dialect instance.
* <p/>
* If a dialect is explicitly named in the incoming properties, it is used. Otherwise, it is
* determined by dialect resolvers based on the passed connection.
* <p/>
* An exception is thrown if a dialect was not explicitly set and no resolver could make
* the determination from the given connection.
*
* @param properties The configuration properties.
* @param connection The configured connection.
* @return The appropriate dialect instance.
* @throws HibernateException No dialect specified and no resolver could make the determination.
*/
public static Dialect buildDialect(Properties properties, Connection connection) throws HibernateException {
String dialectName = properties.getProperty( Environment.DIALECT );
if ( dialectName == null ) {
return determineDialect( connection );
}
else {
return constructDialect( dialectName );
}
}
public static Dialect buildDialect(Properties properties) {
String dialectName = properties.getProperty( Environment.DIALECT );
if ( dialectName == null ) {
throw new HibernateException( "'hibernate.dialect' must be set when no Connection avalable" );
}
return constructDialect( dialectName );
}
/**
* Determine the appropriate Dialect to use given the connection.
*
* @param connection The configured connection.
* @return The appropriate dialect instance.
*
* @throws HibernateException No connection given or no resolver could make
* the determination from the given connection.
*/
private static Dialect determineDialect(Connection connection) {
if ( connection == null ) {
throw new HibernateException( "Connection cannot be null when 'hibernate.dialect' not set" );
}
try {
final DatabaseMetaData databaseMetaData = connection.getMetaData();
final Dialect dialect = DIALECT_RESOLVERS.resolveDialect( databaseMetaData );
if ( dialect == null ) {
throw new HibernateException(
"Unable to determine Dialect to use [name=" + databaseMetaData.getDatabaseProductName() +
", majorVersion=" + databaseMetaData.getDatabaseMajorVersion() +
"]; user must register resolver or explicitly set 'hibernate.dialect'"
);
}
return dialect;
}
catch ( SQLException sqlException ) {
throw new HibernateException(
"Unable to access java.sql.DatabaseMetaData to determine appropriate Dialect to use",
sqlException
);
}
}
/**
* Returns a dialect instance given the name of the class to use.
*
* @param dialectName The name of the dialect class.
*
* @return The dialect instance.
*/
public static Dialect constructDialect(String dialectName) {
try {
return ( Dialect ) ReflectHelper.classForName( dialectName ).newInstance();
}
catch ( ClassNotFoundException cnfe ) {
throw new HibernateException( "Dialect class not found: " + dialectName, cnfe );
}
catch ( Exception e ) {
throw new HibernateException( "Could not instantiate dialect class", e );
}
}
}