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Cayenne Object Persistence Framework
/*****************************************************************
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.
****************************************************************/
package org.apache.cayenne.access.jdbc;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.Map;
import org.apache.cayenne.CayenneRuntimeException;
import org.apache.cayenne.access.types.ExtendedType;
import org.apache.cayenne.access.types.ExtendedTypeMap;
/**
* A descriptor of a result row obtained from a database.
*
* @since 1.2
* @author Andrei Adamchik
*/
// replaces 1.1 ResultDescriptor
public class RowDescriptor {
protected ColumnDescriptor[] columns;
protected ExtendedType[] converters;
/**
* Creates an empty RowDescriptor. Intended mainly for testing and use by subclasses.
*/
protected RowDescriptor() {
}
/**
* Creates a RowDescriptor for an array of columns.
*/
public RowDescriptor(ColumnDescriptor[] columns, ExtendedTypeMap types) {
this.columns = columns;
indexTypes(types);
}
/**
* Creates new RowDescriptor using ResultSet metadata to determine the columns.
*/
public RowDescriptor(ResultSet resultSet, ExtendedTypeMap types) {
this(resultSet, types, null);
}
/**
* Creates new RowDescriptor using ResultSet metadata to determine the columns. Note
* that if javaTypeOverrides array is null, default JDBC to Java types mapping is
* used.
*/
public RowDescriptor(ResultSet resultSet, ExtendedTypeMap types, Map javaTypeOverrides) {
initFromResultSet(resultSet);
if (javaTypeOverrides != null) {
overrideJavaTypes(javaTypeOverrides);
}
indexTypes(types);
}
/**
* Initializes converters for columns.
*/
protected void indexTypes(ExtendedTypeMap types) {
this.converters = new ExtendedType[columns.length];
for (int i = 0; i < columns.length; i++) {
converters[i] = types.getRegisteredType(columns[i].getJavaClass());
}
}
/**
* Builds columns list from ResultSet metadata.
*/
protected void initFromResultSet(ResultSet resultSet) {
try {
ResultSetMetaData md = resultSet.getMetaData();
int len = md.getColumnCount();
if (len == 0) {
throw new CayenneRuntimeException("No columns in ResultSet.");
}
this.columns = new ColumnDescriptor[len];
for (int i = 0; i < len; i++) {
columns[i] = new ColumnDescriptor(md, i + 1);
}
}
catch (SQLException sqex) {
throw new CayenneRuntimeException("Error reading metadata.", sqex);
}
}
/**
* Overrides Java types of result columns. Keys in the map must correspond to the
* names of the columns.
*/
protected void overrideJavaTypes(Map overrides) {
for (int i = 0; i < columns.length; i++) {
String type = (String) overrides.get(columns[i].getName());
if (type != null) {
columns[i].setJavaClass(type);
}
}
}
/**
* Returns a number of columns in a row.
*/
public int getWidth() {
return columns.length;
}
/**
* Returns column descriptors.
*/
public ColumnDescriptor[] getColumns() {
return columns;
}
/**
* Returns extended types for columns.
*/
public ExtendedType[] getConverters() {
return converters;
}
}
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