columnmaprowmapper.java

spring的源代码

/*
 * Copyright 2002-2005 the original author or authors.
 *
 * 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.
 */

package org.springframework.jdbc.core;

import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.Map;

import org.springframework.core.CollectionFactory;
import org.springframework.jdbc.support.JdbcUtils;

/**
 * RowMapper implementation that creates a <code>java.util.Map</code>
 * for each row, representing all columns as key-value pairs: one
 * entry for each column, with the column name as key.
 *
 * <p>The Map implementation to use and the key to use for each column
 * in the column Map can be customized through overriding
 * <code>createColumnMap</code> and <code>getColumnKey</code>, respectively.
 *
 * @author Juergen Hoeller
 * @since 1.2
 * @see #createColumnMap
 * @see #getColumnKey
 * @see JdbcTemplate#queryForList(String)
 * @see JdbcTemplate#queryForMap(String)
 */
public class ColumnMapRowMapper implements RowMapper {

	public Object mapRow(ResultSet rs, int rowNum) throws SQLException {
		ResultSetMetaData rsmd = rs.getMetaData();
		int columnCount = rsmd.getColumnCount();
		Map mapOfColValues = createColumnMap(columnCount);
		for (int i = 1; i <= columnCount; i++) {
			String key = getColumnKey(rsmd.getColumnName(i));
			Object obj = getColumnValue(rs, i);
			mapOfColValues.put(key, obj);
		}
		return mapOfColValues;
	}

	/**
	 * Create a Map instance to be used as column map.
	 * <p>By default, a linked case-insensitive Map will be created if possible,
	 * else a plain HashMap (see Spring's CollectionFactory).
	 * @param columnCount the column count, to be used as initial
	 * capacity for the Map
	 * @return the new Map instance
	 * @see org.springframework.core.CollectionFactory#createLinkedCaseInsensitiveMapIfPossible
	 */
	protected Map createColumnMap(int columnCount) {
		return CollectionFactory.createLinkedCaseInsensitiveMapIfPossible(columnCount);
	}

	/**
	 * Determine the key to use for the given column in the column Map.
	 * @param columnName the column name as returned by the ResultSet
	 * @return the column key to use
	 * @see java.sql.ResultSetMetaData#getColumnName
	 */
	protected String getColumnKey(String columnName) {
		return columnName;
	}

	/**
	 * Retrieve a JDBC object value for the specified column.
	 * <p>The default implementation uses the <code>getObject</code> method.
	 * Additionally, this implementation includes a "hack" to get around Oracle
	 * returning a non standard object for their TIMESTAMP datatype.
	 * @param rs is the ResultSet holding the data
	 * @param index is the column index
	 * @return the Object returned
	 * @see org.springframework.jdbc.support.JdbcUtils#getResultSetValue
	 */
	protected Object getColumnValue(ResultSet rs, int index) throws SQLException {
		return JdbcUtils.getResultSetValue(rs, index);
	}

}