package org.apache.ojb.broker.accesslayer.sql;
/* Copyright 2002-2005 The Apache Software Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import java.lang.ref.WeakReference;
import org.apache.ojb.broker.OJBRuntimeException;
import org.apache.ojb.broker.PersistenceBrokerException;
import org.apache.ojb.broker.metadata.ClassDescriptor;
import org.apache.ojb.broker.metadata.FieldDescriptor;
import org.apache.ojb.broker.util.logging.Logger;
/**
* Model simple Statements based on ClassDescriptor and/or PrimaryKey
*
* @author <a href="mailto:jbraeuchi@hotmail.com">Jakob Braeuchi</a>
* @version $Id: SqlPkStatement.java,v 1.5.2.2 2005/12/21 22:23:44 tomdz Exp $
*/
public abstract class SqlPkStatement implements SqlStatement
{
// arminw: Use weak reference to allow GC of removed metadata instances
private WeakReference m_classDescriptor;
private Logger m_logger;
/** Constructor for SqlPkStatement. */
public SqlPkStatement(ClassDescriptor aCld, Logger aLogger)
{
super();
m_classDescriptor = new WeakReference(aCld);
m_logger = aLogger;
}
/** append table name */
protected void appendTable(ClassDescriptor cld, StringBuffer stmt)
{
stmt.append(cld.getFullTableName());
}
/**
* Returns the logger.
*
* @return Logger
*/
protected Logger getLogger()
{
return m_logger;
}
/**
* Returns the classDescriptor.
*
* @return ClassDescriptor
*/
protected ClassDescriptor getClassDescriptor()
{
ClassDescriptor cld = (ClassDescriptor) m_classDescriptor.get();
if(cld == null)
{
throw new OJBRuntimeException("Requested ClassDescriptor instance was already GC by JVM");
}
return cld;
}
/**
* Generate a sql where-clause for the array of fields
*
* @param fields array containing all columns used in WHERE clause
*/
protected void appendWhereClause(FieldDescriptor[] fields, StringBuffer stmt) throws PersistenceBrokerException
{
stmt.append(" WHERE ");
for(int i = 0; i < fields.length; i++)
{
FieldDescriptor fmd = fields[i];
stmt.append(fmd.getColumnName());
stmt.append(" = ? ");
if(i < fields.length - 1)
{
stmt.append(" AND ");
}
}
}
/**
* Generate a where clause for a prepared Statement.
* Only primary key and locking fields are used in this where clause
*
* @param cld the ClassDescriptor
* @param useLocking true if locking fields should be included
* @param stmt the StatementBuffer
*/
protected void appendWhereClause(ClassDescriptor cld, boolean useLocking, StringBuffer stmt)
{
FieldDescriptor[] pkFields = cld.getPkFields();
FieldDescriptor[] fields;
fields = pkFields;
if(useLocking)
{
FieldDescriptor[] lockingFields = cld.getLockingFields();
if(lockingFields.length > 0)
{
fields = new FieldDescriptor[pkFields.length + lockingFields.length];
System.arraycopy(pkFields, 0, fields, 0, pkFields.length);
System.arraycopy(lockingFields, 0, fields, pkFields.length, lockingFields.length);
}
}
appendWhereClause(fields, stmt);
}
}