/*
 * $Header: /home/cvs/commons/dbutils-1.0/ja/src/org/apache/commons/dbutils/handlers/MapHandler.java,v 1.1.1.1 2004/02/13 10:02:04 hioki Exp $
 * $Revision: 1.1.1.1 $
 * $Date: 2004/02/13 10:02:04 $
 * 
 * ====================================================================
 *
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2003 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowledgement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgement may appear in the software itself,
 *    if and wherever such third-party acknowledgements normally appear.
 *
 * 4. The names "The Jakarta Project", "Commons", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache"
 *    nor may "Apache" appear in their names without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.commons.dbutils.handlers;

import java.sql.ResultSet;
import java.sql.SQLException;

import org.apache.commons.dbutils.BasicRowProcessor;
import org.apache.commons.dbutils.ResultSetHandler;
import org.apache.commons.dbutils.RowProcessor;

/**
 * ResultSetの先頭行をMapへ変換するResultSetHandlerの実装です。 このクラスはスレッドセーフです。
 * {@primary <code>ResultSetHandler</code> implementation that converts the first
 * <code>ResultSet</code> row into a <code>Map</code>. This class is thread 
 * safe.}
 * 
 * @see ResultSetHandler
 * @author Juozas Baliuka
 * @author David Graham
 * @translator 小川 環
 * @editor 日置 聡
 * @status underproof
 * @update 2003/12/22
 */
public class MapHandler implements ResultSetHandler {

    /**
     * The RowProcessor implementation to use when converting rows 
     * into Maps.
     */
    private RowProcessor convert = BasicRowProcessor.instance();

    /** 
     * 変換に <code>BasicRowProcessor</code> を使用する MapHandler の新規インスタンスを作成します。
     * {@primary Creates a new instance of MapHandler using a 
     * <code>BasicRowProcessor</code> for conversion.}
     */
    public MapHandler() {
        super();
    }

    /** 
     * MapHandlerの新規インスタンスを作成します。 
     * {@primary Creates a new instance of MapHandler.}
     * 
     * @param convert 行を Map へ変換する際に使用する <code>RowProcessor</code> 実装。
     * {@primary The <code>RowProcessor</code> implementation 
     * to use when converting rows into Maps.}
     */
    public MapHandler(RowProcessor convert) {
        super();
        this.convert = convert;
    }

    /**
     * <code>ResultSet</code> の先頭行を <code>Map</code> へ変換します。
     * {@primary Converts the first row in the <code>ResultSet</code> into a 
     * <code>Map</code>.}
     * 
     * @return 先頭行から取得した値を入れた <code>Map</code>、 <code>ResultSet</code> が0行の場合は <code>null</code>。 
     * {@primary A <code>Map</code> with the values from the first row or 
     * <code>null</code> if there are no rows in the <code>ResultSet</code>. }
     * 
     * @throws SQLException
     * 
     * @see org.apache.commons.dbutils.ResultSetHandler#handle(java.sql.ResultSet)
     */
    public Object handle(ResultSet rs) throws SQLException {
        return rs.next() ? this.convert.toMap(rs) : null;
    }

}