    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.handlers;
    018
    019import java.sql.ResultSet;
    020import java.sql.SQLException;
    021
    022import org.apache.commons.dbutils.BasicRowProcessor;
    023import org.apache.commons.dbutils.ResultSetHandler;
    024import org.apache.commons.dbutils.RowProcessor;
    025
    026/**
    027 * {@code ResultSetHandler} implementation that converts a
    028 * {@code ResultSet} into an {@code Object[]}. This class is
    029 * thread safe.
    030 *
    031 * @see org.apache.commons.dbutils.ResultSetHandler
    032 */
    033public class ArrayHandler implements ResultSetHandler<Object[]> {
    034
    035    /**
    036     * Singleton processor instance that handlers share to save memory.  Notice
    037     * the default scoping to allow only classes in this package to use this
    038     * instance.
    039     */
    040    static final RowProcessor ROW_PROCESSOR = new BasicRowProcessor();
    041
    042    /**
    043     * An empty array to return when no more rows are available in the ResultSet.
    044     */
    045    private static final Object[] EMPTY_ARRAY = {};
    046
    047    /**
    048     * The RowProcessor implementation to use when converting rows
    049     * into arrays.
    050     */
    051    private final RowProcessor convert;
    052
    053    /**
    054     * Creates a new instance of ArrayHandler using a
    055     * {@code BasicRowProcessor} for conversion.
    056     */
    057    public ArrayHandler() {
    058        this(ROW_PROCESSOR);
    059    }
    060
    061    /**
    062     * Creates a new instance of ArrayHandler.
    063     *
    064     * @param convert The {@code RowProcessor} implementation
    065     * to use when converting rows into arrays.
    066     */
    067    public ArrayHandler(final RowProcessor convert) {
    068        this.convert = convert;
    069    }
    070
    071    /**
    072     * Places the column values from the first row in an {@code Object[]}.
    073     * @param resultSet {@code ResultSet} to process.
    074     * @return An Object[]. If there are no rows in the {@code ResultSet}
    075     * an empty array will be returned.
    076     *
    077     * @throws SQLException if a database access error occurs
    078     * @see org.apache.commons.dbutils.ResultSetHandler#handle(java.sql.ResultSet)
    079     */
    080    @Override
    081    public Object[] handle(final ResultSet resultSet) throws SQLException {
    082        return resultSet.next() ? this.convert.toArray(resultSet) : EMPTY_ARRAY;
    083    }
    084
    085}