org.springframework.jdbc.core.ColumnMapRowMapper.java Source code

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Here is the source code for org.springframework.jdbc.core.ColumnMapRowMapper.java

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/*
 * Copyright 2002-2018 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
 *
 *      https://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.jdbc.support.JdbcUtils;
import org.springframework.lang.Nullable;
import org.springframework.util.LinkedCaseInsensitiveMap;

/**
 * {@link RowMapper} implementation that creates a {@code java.util.Map}
 * 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
 * {@link #createColumnMap} and {@link #getColumnKey}, respectively.
 *
 * <p><b>Note:</b> By default, ColumnMapRowMapper will try to build a linked Map
 * with case-insensitive keys, to preserve column order as well as allow any
 * casing to be used for column names. This requires Commons Collections on the
 * classpath (which will be autodetected). Else, the fallback is a standard linked
 * HashMap, which will still preserve column order but requires the application
 * to specify the column names in the same casing as exposed by the driver.
 *
 * @author Juergen Hoeller
 * @since 1.2
 * @see JdbcTemplate#queryForList(String)
 * @see JdbcTemplate#queryForMap(String)
 */
public class ColumnMapRowMapper implements RowMapper<Map<String, Object>> {

    @Override
    public Map<String, Object> mapRow(ResultSet rs, int rowNum) throws SQLException {
        ResultSetMetaData rsmd = rs.getMetaData();
        int columnCount = rsmd.getColumnCount();
        Map<String, Object> mapOfColumnValues = createColumnMap(columnCount);
        for (int i = 1; i <= columnCount; i++) {
            String column = JdbcUtils.lookupColumnName(rsmd, i);
            mapOfColumnValues.putIfAbsent(getColumnKey(column), getColumnValue(rs, i));
        }
        return mapOfColumnValues;
    }

    /**
     * Create a Map instance to be used as column map.
     * <p>By default, a linked case-insensitive Map will be created.
     * @param columnCount the column count, to be used as initial
     * capacity for the Map
     * @return the new Map instance
     * @see org.springframework.util.LinkedCaseInsensitiveMap
     */
    protected Map<String, Object> createColumnMap(int columnCount) {
        return new LinkedCaseInsensitiveMap<>(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} 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
     */
    @Nullable
    protected Object getColumnValue(ResultSet rs, int index) throws SQLException {
        return JdbcUtils.getResultSetValue(rs, index);
    }

}