beanhandler.java

实现了从Google

/* 
 * $Header: /home/cvs/jakarta-commons/dbutils/src/java/org/apache/commons/dbutils/handlers/BeanHandler.java,v 1.1 2003/11/02 19:15:24 dgraham Exp $
 * $Revision: 1.1 $
 * $Date: 2003/11/02 19:15:24 $
 * 
 * ====================================================================
 * 
 * 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.
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 * 4. The names "The Jakarta Project", "Commons", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
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 * 5. Products derived from this software may not be called "Apache"
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 * This software consists of voluntary contributions made by many
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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;

/**
 * <code>ResultSetHandler</code> implementation that converts the first 
 * <code>ResultSet</code> row into a JavaBean. This class is thread safe.
 * 
 * @see ResultSetHandler
 * 
 * @author Juozas Baliuka
 * @author David Graham
 */
public class BeanHandler implements ResultSetHandler {

    /**
     * The Class of beans produced by this handler.
     */
    private Class type = null;

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

    /** 
     * Creates a new instance of BeanHandler.
     * 
     * @param type The Class that objects returned from <code>handle()</code>
     * are created from.
     */
    public BeanHandler(Class type) {
        this.type = type;
    }

    /** 
     * Creates a new instance of BeanHandler.
     * 
     * @param type The Class that objects returned from <code>handle()</code>
     * are created from.
     * @param convert The <code>RowProcessor</code> implementation 
     * to use when converting rows into beans.
     */
    public BeanHandler(Class type, RowProcessor convert) {
        this.type = type;
        this.convert = convert;
    }

    /**
     * Convert the first row of the <code>ResultSet</code> into a bean with the
     * <code>Class</code> given in the constructor.
     * 
     * @return An initialized JavaBean or <code>null</code> if there were 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.toBean(rs, this.type) : null;
    }

}