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 * Defines how to process columns when constructing a bean from a {@link ResultSet}. Instances do the work of retrieving data from a {@code ResultSet}.
024 *
025 * @param <T> The return type.
026 */
027public interface ColumnHandler<T> {
028
029    /**
030     * Retrieves the current row's column value from a {@link ResultSet} and stores it into an instance of {@code propType}. This method is only called if
031     * {@link #match(Class)} returns true.
032     *
033     * @param resultSet   The source result set. This must be on the correct row.
034     * @param columnIndex The position of the column to retrieve, a 1-based index.
035     * @return The converted value or the original value if something doesn't work out.
036     * @throws SQLException if the columnIndex is not valid; if a database access error occurs or this method is called on a closed result set
037     */
038    T apply(ResultSet resultSet, int columnIndex) throws SQLException;
039
040    /**
041     * Tests whether to handle a column targeted for a value type matching {@code propType}.
042     *
043     * @param propType The type of the target parameter.
044     * @return true is this property handler handles this {@code propType}; false otherwise.
045     */
046    boolean match(Class<?> propType);
047}