001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.commons.dbutils.handlers;
018    
019    import java.sql.ResultSet;
020    import java.sql.SQLException;
021    
022    /**
023     * <code>ResultSetHandler</code> implementation that converts one
024     * <code>ResultSet</code> column into a <code>List</code> of
025     * <code>Object</code>s. This class is thread safe.
026     *
027     * @see org.apache.commons.dbutils.ResultSetHandler
028     * @since DbUtils 1.1
029     */
030    public class ColumnListHandler extends AbstractListHandler<Object> {
031    
032        /**
033         * The column number to retrieve.
034         */
035        private final int columnIndex;
036    
037        /**
038         * The column name to retrieve.  Either columnName or columnIndex
039         * will be used but never both.
040         */
041        private final String columnName;
042    
043        /**
044         * Creates a new instance of ColumnListHandler.  The first column of each
045         * row will be returned from <code>handle()</code>.
046         */
047        public ColumnListHandler() {
048            this(1, null);
049        }
050    
051        /**
052         * Creates a new instance of ColumnListHandler.
053         *
054         * @param columnIndex The index of the column to retrieve from the
055         * <code>ResultSet</code>.
056         */
057        public ColumnListHandler(int columnIndex) {
058            this(columnIndex, null);
059        }
060    
061        /**
062         * Creates a new instance of ColumnListHandler.
063         *
064         * @param columnName The name of the column to retrieve from the
065         * <code>ResultSet</code>.
066         */
067        public ColumnListHandler(String columnName) {
068            this(1, columnName);
069        }
070    
071        /** Private Helper
072         * @param columnIndex The index of the column to retrieve from the
073         * <code>ResultSet</code>.
074         * @param columnName The name of the column to retrieve from the
075         * <code>ResultSet</code>.
076         */
077        private ColumnListHandler(int columnIndex, String columnName) {
078            super();
079            this.columnIndex = columnIndex;
080            this.columnName = columnName;
081        }
082    
083        /**
084         * Returns one <code>ResultSet</code> column value as <code>Object</code>.
085         * @param rs <code>ResultSet</code> to process.
086         * @return <code>Object</code>, never <code>null</code>.
087         *
088         * @throws SQLException if a database access error occurs
089         *
090         * @see org.apache.commons.dbutils.handlers.AbstractListHandler#handle(ResultSet)
091         */
092        @Override
093        protected Object handleRow(ResultSet rs) throws SQLException {
094            if (this.columnName == null) {
095                return rs.getObject(this.columnIndex);
096            } else {
097                return rs.getObject(this.columnName);
098            }
099       }
100    
101    }