BasicRowProcessor.java
/*
* 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.commons.dbutils;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;
/**
* Basic implementation of the {@code RowProcessor} interface.
*
* <p>
* This class is thread-safe.
* </p>
*
* @see RowProcessor
*/
public class BasicRowProcessor implements RowProcessor {
/**
* A Map that converts all keys to lowercase Strings for case insensitive
* lookups. This is needed for the toMap() implementation because
* databases don't consistently handle the casing of column names.
*
* <p>The keys are stored as they are given [BUG #DBUTILS-34], so we maintain
* an internal mapping from lowercase keys to the real keys in order to
* achieve the case insensitive lookup.
*
* <p>Note: This implementation does not allow {@code null}
* for key, whereas {@link LinkedHashMap} does, because of the code:
* <pre>
* key.toString().toLowerCase()
* </pre>
*/
private static final class CaseInsensitiveHashMap extends LinkedHashMap<String, Object> {
/**
* Required for serialization support.
*
* @see java.io.Serializable
*/
private static final long serialVersionUID = -2848100435296897392L;
/**
* The internal mapping from lowercase keys to the real keys.
*
* <p>
* Any query operation using the key
* ({@link #get(Object)}, {@link #containsKey(Object)})
* is done in three steps:
* <ul>
* <li>convert the parameter key to lower case</li>
* <li>get the actual key that corresponds to the lower case key</li>
* <li>query the map with the actual key</li>
* </ul>
* </p>
*/
private final Map<String, String> lowerCaseMap = new HashMap<>();
private CaseInsensitiveHashMap(final int initialCapacity) {
super(initialCapacity);
}
/** {@inheritDoc} */
@Override
public boolean containsKey(final Object key) {
final Object realKey = lowerCaseMap.get(key.toString().toLowerCase(Locale.ENGLISH));
return super.containsKey(realKey);
// Possible optimisation here:
// Since the lowerCaseMap contains a mapping for all the keys,
// we could just do this:
// return lowerCaseMap.containsKey(key.toString().toLowerCase());
}
/** {@inheritDoc} */
@Override
public Object get(final Object key) {
final Object realKey = lowerCaseMap.get(key.toString().toLowerCase(Locale.ENGLISH));
return super.get(realKey);
}
/** {@inheritDoc} */
@Override
public Object put(final String key, final Object value) {
/*
* In order to keep the map and lowerCaseMap synchronized,
* we have to remove the old mapping before putting the
* new one. Indeed, oldKey and key are not necessarily equals.
* (That's why we call super.remove(oldKey) and not just
* super.put(key, value))
*/
final Object oldKey = lowerCaseMap.put(key.toLowerCase(Locale.ENGLISH), key);
final Object oldValue = super.remove(oldKey);
super.put(key, value);
return oldValue;
}
/** {@inheritDoc} */
@Override
public void putAll(final Map<? extends String, ?> m) {
m.forEach(this::put);
}
/** {@inheritDoc} */
@Override
public Object remove(final Object key) {
final Object realKey = lowerCaseMap.remove(key.toString().toLowerCase(Locale.ENGLISH));
return super.remove(realKey);
}
}
/**
* The default BeanProcessor instance to use if not supplied in the
* constructor.
*/
private static final BeanProcessor defaultConvert = new BeanProcessor();
/**
* The Singleton instance of this class.
*/
private static final BasicRowProcessor instance = new BasicRowProcessor();
protected static Map<String, Object> createCaseInsensitiveHashMap(final int cols) {
return new CaseInsensitiveHashMap(cols);
}
/**
* Returns the Singleton instance of this class.
*
* @return The single instance of this class.
* @deprecated Create instances with the constructors instead. This will
* be removed after DbUtils 1.1.
*/
@Deprecated
public static BasicRowProcessor instance() {
return instance;
}
/**
* Use this to process beans.
*/
private final BeanProcessor convert;
/**
* BasicRowProcessor constructor. Bean processing defaults to a
* BeanProcessor instance.
*/
public BasicRowProcessor() {
this(defaultConvert);
}
/**
* BasicRowProcessor constructor.
* @param convert The BeanProcessor to use when converting columns to
* bean properties.
* @since 1.1
*/
public BasicRowProcessor(final BeanProcessor convert) {
this.convert = convert;
}
/**
* Convert a {@code ResultSet} row into an {@code Object[]}.
* This implementation copies column values into the array in the same
* order they're returned from the {@code ResultSet}. Array elements
* will be set to {@code null} if the column was SQL NULL.
*
* @see org.apache.commons.dbutils.RowProcessor#toArray(java.sql.ResultSet)
* @param resultSet ResultSet that supplies the array data
* @throws SQLException if a database access error occurs
* @return the newly created array
*/
@Override
public Object[] toArray(final ResultSet resultSet) throws SQLException {
final ResultSetMetaData meta = resultSet.getMetaData();
final int cols = meta.getColumnCount();
final Object[] result = new Object[cols];
for (int i = 0; i < cols; i++) {
result[i] = resultSet.getObject(i + 1);
}
return result;
}
/**
* Convert a {@code ResultSet} row into a JavaBean. This
* implementation delegates to a BeanProcessor instance.
* @see org.apache.commons.dbutils.RowProcessor#toBean(java.sql.ResultSet, Class)
* @see org.apache.commons.dbutils.BeanProcessor#toBean(java.sql.ResultSet, Class)
* @param <T> The type of bean to create
* @param resultSet ResultSet that supplies the bean data
* @param type Class from which to create the bean instance
* @throws SQLException if a database access error occurs
* @return the newly created bean
*/
@Override
public <T> T toBean(final ResultSet resultSet, final Class<? extends T> type) throws SQLException {
return this.convert.toBean(resultSet, type);
}
/**
* Convert a {@code ResultSet} into a {@code List} of JavaBeans.
* This implementation delegates to a BeanProcessor instance.
* @see org.apache.commons.dbutils.RowProcessor#toBeanList(java.sql.ResultSet, Class)
* @see org.apache.commons.dbutils.BeanProcessor#toBeanList(java.sql.ResultSet, Class)
* @param <T> The type of bean to create
* @param resultSet ResultSet that supplies the bean data
* @param type Class from which to create the bean instance
* @throws SQLException if a database access error occurs
* @return A {@code List} of beans with the given type in the order
* they were returned by the {@code ResultSet}.
*/
@Override
public <T> List<T> toBeanList(final ResultSet resultSet, final Class<? extends T> type) throws SQLException {
return this.convert.toBeanList(resultSet, type);
}
/**
* Convert a {@code ResultSet} row into a {@code Map}.
*
* <p>
* This implementation returns a {@code Map} with case insensitive column names as keys. Calls to
* {@code map.get("COL")} and {@code map.get("col")} return the same value. Furthermore this implementation
* will return an ordered map, that preserves the ordering of the columns in the ResultSet, so that iterating over
* the entry set of the returned map will return the first column of the ResultSet, then the second and so forth.
* </p>
*
* @param resultSet ResultSet that supplies the map data
* @return the newly created Map
* @throws SQLException if a database access error occurs
* @see org.apache.commons.dbutils.RowProcessor#toMap(java.sql.ResultSet)
*/
@Override
public Map<String, Object> toMap(final ResultSet resultSet) throws SQLException {
final ResultSetMetaData rsmd = resultSet.getMetaData();
final int cols = rsmd.getColumnCount();
final Map<String, Object> result = createCaseInsensitiveHashMap(cols);
for (int i = 1; i <= cols; i++) {
String propKey = rsmd.getColumnLabel(i);
if (null == propKey || 0 == propKey.length()) {
propKey = rsmd.getColumnName(i);
}
if (null == propKey || 0 == propKey.length()) {
// The column index can't be null
propKey = Integer.toString(i);
}
result.put(propKey, resultSet.getObject(i));
}
return result;
}
}