    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;
    021import java.util.Iterator;
    022
    023/**
    024 * <p>
    025 * Wraps a {@code ResultSet} in an {@code Iterator&lt;Object[]&gt;}.  This is useful
    026 * when you want to present a non-database application layer with domain
    027 * neutral data.
    028 * </p>
    029 *
    030 * <p>
    031 * This implementation requires the {@code ResultSet.isLast()} method
    032 * to be implemented.
    033 * </p>
    034 */
    035public class ResultSetIterator implements Iterator<Object[]> {
    036
    037    /**
    038     * Generates an {@code Iterable}, suitable for use in for-each loops.
    039     *
    040     * @param resultSet Wrap this {@code ResultSet} in an {@code Iterator}.
    041     * @return an {@code Iterable}, suitable for use in for-each loops.
    042     */
    043    public static Iterable<Object[]> iterable(final ResultSet resultSet) {
    044        return () -> new ResultSetIterator(resultSet);
    045    }
    046
    047    /**
    048     * The wrapped {@code ResultSet}.
    049     */
    050    private final ResultSet resultSet;
    051
    052    /**
    053     * The processor to use when converting a row into an Object[].
    054     */
    055    private final RowProcessor convert;
    056
    057    /**
    058     * Constructor for ResultSetIterator.
    059     * @param resultSet Wrap this {@code ResultSet} in an {@code Iterator}.
    060     */
    061    public ResultSetIterator(final ResultSet resultSet) {
    062        this(resultSet, new BasicRowProcessor());
    063    }
    064
    065    /**
    066     * Constructor for ResultSetIterator.
    067     * @param resultSet Wrap this {@code ResultSet} in an {@code Iterator}.
    068     * @param convert The processor to use when converting a row into an
    069     * {@code Object[]}.  Defaults to a
    070     * {@code BasicRowProcessor}.
    071     */
    072    public ResultSetIterator(final ResultSet resultSet, final RowProcessor convert) {
    073        this.resultSet = resultSet;
    074        this.convert = convert;
    075    }
    076
    077    /**
    078     * Returns true if there are more rows in the ResultSet.
    079     * @return boolean {@code true} if there are more rows
    080     * @throws RuntimeException if an SQLException occurs.
    081     */
    082    @Override
    083    public boolean hasNext() {
    084        try {
    085            return !resultSet.isLast();
    086        } catch (final SQLException e) {
    087            rethrow(e);
    088            return false;
    089        }
    090    }
    091
    092    /**
    093     * Returns the next row as an {@code Object[]}.
    094     * @return An {@code Object[]} with the same number of elements as
    095     * columns in the {@code ResultSet}.
    096     * @see java.util.Iterator#next()
    097     * @throws RuntimeException if an SQLException occurs.
    098     */
    099    @Override
    100    public Object[] next() {
    101        try {
    102            resultSet.next();
    103            return this.convert.toArray(resultSet);
    104        } catch (final SQLException e) {
    105            rethrow(e);
    106            return null;
    107        }
    108    }
    109
    110    /**
    111     * Deletes the current row from the {@code ResultSet}.
    112     * @see java.util.Iterator#remove()
    113     * @throws RuntimeException if an SQLException occurs.
    114     */
    115    @Override
    116    public void remove() {
    117        try {
    118            this.resultSet.deleteRow();
    119        } catch (final SQLException e) {
    120            rethrow(e);
    121        }
    122    }
    123
    124    /**
    125     * Rethrow the SQLException as a RuntimeException.  This implementation
    126     * creates a new RuntimeException with the SQLException's error message.
    127     * @param e SQLException to rethrow
    128     * @since 1.1
    129     */
    130    protected void rethrow(final SQLException e) {
    131        throw new RuntimeException(e.getMessage());
    132    }
    133
    134}