001/*
002 * Copyright 2002-2012 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.object;
018
019import java.sql.ResultSet;
020import java.sql.SQLException;
021import java.util.Map;
022import javax.sql.DataSource;
023
024import org.springframework.jdbc.core.RowMapper;
025
026/**
027 * Reusable RDBMS query in which concrete subclasses must implement
028 * the abstract updateRow(ResultSet, int, context) method to update each
029 * row of the JDBC ResultSet and optionally map contents into an object.
030 *
031 * <p>Subclasses can be constructed providing SQL, parameter types
032 * and a DataSource. SQL will often vary between subclasses.
033 *
034 * @author Thomas Risberg
035 * @see org.springframework.jdbc.object.SqlQuery
036 */
037public abstract class UpdatableSqlQuery<T> extends SqlQuery<T> {
038
039        /**
040         * Constructor to allow use as a JavaBean
041         */
042        public UpdatableSqlQuery() {
043                setUpdatableResults(true);
044        }
045
046        /**
047         * Convenient constructor with DataSource and SQL string.
048         * @param ds DataSource to use to get connections
049         * @param sql SQL to run
050         */
051        public UpdatableSqlQuery(DataSource ds, String sql) {
052                super(ds, sql);
053                setUpdatableResults(true);
054        }
055
056
057        /**
058         * Implementation of the superclass template method. This invokes the subclass's
059         * implementation of the {@code updateRow()} method.
060         */
061        @Override
062        protected RowMapper<T> newRowMapper(Object[] parameters, Map<?, ?> context) {
063                return new RowMapperImpl(context);
064        }
065
066        /**
067         * Subclasses must implement this method to update each row of the
068         * ResultSet and optionally create object of the result type.
069         * @param rs ResultSet we're working through
070         * @param rowNum row number (from 0) we're up to
071         * @param context passed to the execute() method.
072         * It can be {@code null} if no contextual information is need.  If you
073         * need to pass in data for each row, you can pass in a HashMap with
074         * the primary key of the row being the key for the HashMap.  That way
075         * it is easy to locate the updates for each row
076         * @return an object of the result type
077         * @throws SQLException if there's an error updateing data.
078         * Subclasses can simply not catch SQLExceptions, relying on the
079         * framework to clean up.
080         */
081        protected abstract T updateRow(ResultSet rs, int rowNum, Map<?, ?> context) throws SQLException;
082
083
084        /**
085         * Implementation of RowMapper that calls the enclosing
086         * class's {@code updateRow()} method for each row.
087         */
088        protected class RowMapperImpl implements RowMapper<T> {
089
090                private final Map<?, ?> context;
091
092                public RowMapperImpl(Map<?, ?> context) {
093                        this.context = context;
094                }
095
096                @Override
097                public T mapRow(ResultSet rs, int rowNum) throws SQLException {
098                        T result = updateRow(rs, rowNum, this.context);
099                        rs.updateRow();
100                        return result;
101                }
102        }
103
104}