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 */
017package org.apache.commons.dbutils;
018
019import java.sql.ResultSet;
020import java.sql.SQLException;
021
022/**
023 * Interface to define how implementations can interact with column handling when constructing a bean from a
024 * {@link java.sql.ResultSet}.  ColumnHandlers do the work of retrieving data correctly from the {@code ResultSet}.
025 */
026public interface ColumnHandler {
027    /**
028     * Test whether this {@code ColumnHandler} wants to handle a column targeted for a value type matching
029     * {@code propType}.
030     *
031     * @param propType The type of the target parameter.
032     * @return true is this property handler can/wants to handle this value; false otherwise.
033     */
034    boolean match(Class<?> propType);
035
036    /**
037     * Do the work required to retrieve and store a column from {@code ResultSet} into something of type
038     * {@code propType}. This method is called only if this handler responded {@code true} after a call to
039     * {@link #match(Class)}.
040     *
041     * @param rs The result set to get data from. This should be moved to the correct row already.
042     * @param columnIndex The position of the column to retrieve.
043     * @return The converted value or the original value if something doesn't work out.
044     * @throws SQLException if the columnIndex is not valid; if a database access error occurs or this method is
045     *                called on a closed result set
046     */
047    Object apply(ResultSet rs, int columnIndex) throws SQLException;
048}