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.object;
018
019import java.sql.ResultSet;
020import java.sql.SQLException;
021import java.util.Map;
022
023import javax.sql.DataSource;
024
025import org.springframework.jdbc.core.RowMapper;
026import org.springframework.lang.Nullable;
027
028/**
029 * Reusable RDBMS query in which concrete subclasses must implement
030 * the abstract updateRow(ResultSet, int, context) method to update each
031 * row of the JDBC ResultSet and optionally map contents into an object.
032 *
033 * <p>Subclasses can be constructed providing SQL, parameter types
034 * and a DataSource. SQL will often vary between subclasses.
035 *
036 * @author Thomas Risberg
037 * @param <T> the result type
038 * @see org.springframework.jdbc.object.SqlQuery
039 */
040public abstract class UpdatableSqlQuery<T> extends SqlQuery<T> {
041
042        /**
043         * Constructor to allow use as a JavaBean.
044         */
045        public UpdatableSqlQuery() {
046                setUpdatableResults(true);
047        }
048
049        /**
050         * Convenient constructor with DataSource and SQL string.
051         * @param ds the DataSource to use to get connections
052         * @param sql the SQL to run
053         */
054        public UpdatableSqlQuery(DataSource ds, String sql) {
055                super(ds, sql);
056                setUpdatableResults(true);
057        }
058
059
060        /**
061         * Implementation of the superclass template method. This invokes the subclass's
062         * implementation of the {@code updateRow()} method.
063         */
064        @Override
065        protected RowMapper<T> newRowMapper(@Nullable Object[] parameters, @Nullable Map<?, ?> context) {
066                return new RowMapperImpl(context);
067        }
068
069        /**
070         * Subclasses must implement this method to update each row of the
071         * ResultSet and optionally create object of the result type.
072         * @param rs the ResultSet we're working through
073         * @param rowNum row number (from 0) we're up to
074         * @param context passed to the execute() method.
075         * It can be {@code null} if no contextual information is need.  If you
076         * need to pass in data for each row, you can pass in a HashMap with
077         * the primary key of the row being the key for the HashMap.  That way
078         * it is easy to locate the updates for each row
079         * @return an object of the result type
080         * @throws SQLException if there's an error updateing data.
081         * Subclasses can simply not catch SQLExceptions, relying on the
082         * framework to clean up.
083         */
084        protected abstract T updateRow(ResultSet rs, int rowNum, @Nullable Map<?, ?> context) throws SQLException;
085
086
087        /**
088         * Implementation of RowMapper that calls the enclosing
089         * class's {@code updateRow()} method for each row.
090         */
091        protected class RowMapperImpl implements RowMapper<T> {
092
093                @Nullable
094                private final Map<?, ?> context;
095
096                public RowMapperImpl(@Nullable Map<?, ?> context) {
097                        this.context = context;
098                }
099
100                @Override
101                public T mapRow(ResultSet rs, int rowNum) throws SQLException {
102                        T result = updateRow(rs, rowNum, this.context);
103                        rs.updateRow();
104                        return result;
105                }
106        }
107
108}