001/* 002 * Copyright 2002-2018 the original author or authors. 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * https://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 */ 016 017package org.springframework.jdbc.core; 018 019import java.sql.ResultSet; 020import java.sql.SQLException; 021 022import org.springframework.lang.Nullable; 023 024/** 025 * An interface used by {@link JdbcTemplate} for mapping rows of a 026 * {@link java.sql.ResultSet} on a per-row basis. Implementations of this 027 * interface perform the actual work of mapping each row to a result object, 028 * but don't need to worry about exception handling. 029 * {@link java.sql.SQLException SQLExceptions} will be caught and handled 030 * by the calling JdbcTemplate. 031 * 032 * <p>Typically used either for {@link JdbcTemplate}'s query methods 033 * or for out parameters of stored procedures. RowMapper objects are 034 * typically stateless and thus reusable; they are an ideal choice for 035 * implementing row-mapping logic in a single place. 036 * 037 * <p>Alternatively, consider subclassing 038 * {@link org.springframework.jdbc.object.MappingSqlQuery} from the 039 * {@code jdbc.object} package: Instead of working with separate 040 * JdbcTemplate and RowMapper objects, you can build executable query 041 * objects (containing row-mapping logic) in that style. 042 * 043 * @author Thomas Risberg 044 * @author Juergen Hoeller 045 * @param <T> the result type 046 * @see JdbcTemplate 047 * @see RowCallbackHandler 048 * @see ResultSetExtractor 049 * @see org.springframework.jdbc.object.MappingSqlQuery 050 */ 051@FunctionalInterface 052public interface RowMapper<T> { 053 054 /** 055 * Implementations must implement this method to map each row of data 056 * in the ResultSet. This method should not call {@code next()} on 057 * the ResultSet; it is only supposed to map values of the current row. 058 * @param rs the ResultSet to map (pre-initialized for the current row) 059 * @param rowNum the number of the current row 060 * @return the result object for the current row (may be {@code null}) 061 * @throws SQLException if an SQLException is encountered getting 062 * column values (that is, there's no need to catch SQLException) 063 */ 064 @Nullable 065 T mapRow(ResultSet rs, int rowNum) throws SQLException; 066 067}