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.ResultSetHandler;
023import org.apache.commons.dbutils.RowProcessor;
024
025/**
026 * <code>ResultSetHandler</code> implementation that converts the first
027 * <code>ResultSet</code> row into a JavaBean. This class is thread safe.
028 *
029 * @param <T> the target bean type
030 * @see org.apache.commons.dbutils.ResultSetHandler
031 */
032public class BeanHandler<T> implements ResultSetHandler<T> {
033
034    /**
035     * The Class of beans produced by this handler.
036     */
037    private final Class<? extends T> type;
038
039    /**
040     * The RowProcessor implementation to use when converting rows
041     * into beans.
042     */
043    private final RowProcessor convert;
044
045    /**
046     * Creates a new instance of BeanHandler.
047     *
048     * @param type The Class that objects returned from <code>handle()</code>
049     * are created from.
050     */
051    public BeanHandler(Class<? extends T> type) {
052        this(type, ArrayHandler.ROW_PROCESSOR);
053    }
054
055    /**
056     * Creates a new instance of BeanHandler.
057     *
058     * @param type The Class that objects returned from <code>handle()</code>
059     * are created from.
060     * @param convert The <code>RowProcessor</code> implementation
061     * to use when converting rows into beans.
062     */
063    public BeanHandler(Class<? extends T> type, RowProcessor convert) {
064        this.type = type;
065        this.convert = convert;
066    }
067
068    /**
069     * Convert the first row of the <code>ResultSet</code> into a bean with the
070     * <code>Class</code> given in the constructor.
071     * @param rs <code>ResultSet</code> to process.
072     * @return An initialized JavaBean or <code>null</code> if there were no
073     * rows in the <code>ResultSet</code>.
074     *
075     * @throws SQLException if a database access error occurs
076     * @see org.apache.commons.dbutils.ResultSetHandler#handle(java.sql.ResultSet)
077     */
078    @Override
079    public T handle(ResultSet rs) throws SQLException {
080        return rs.next() ? this.convert.toBean(rs, this.type) : null;
081    }
082
083}