    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}