    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 */
    017
    018package org.apache.commons.beanutils;
    019
    020import java.sql.ResultSet;
    021import java.sql.SQLException;
    022import java.util.Iterator;
    023import java.util.Objects;
    024
    025/**
    026 * <p>Implements <code>DynaClass</code> for DynaBeans that wrap the
    027 * <code>java.sql.Row</code> objects of a <code>java.sql.ResultSet</code>.
    028 * The normal usage pattern is something like:</p>
    029 * <pre>
    030 *   ResultSet rs = ...;
    031 *   ResultSetDynaClass rsdc = new ResultSetDynaClass(rs);
    032 *   Iterator rows = rsdc.iterator();
    033 *   while (rows.hasNext())  {
    034 *     DynaBean row = (DynaBean) rows.next();
    035 *     ... process this row ...
    036 *   }
    037 *   rs.close();
    038 * </pre>
    039 *
    040 * <p>Each column in the result set will be represented as a DynaBean
    041 * property of the corresponding name (optionally forced to lower case
    042 * for portability).</p>
    043 *
    044 * <p><strong>WARNING</strong> - Any {@link DynaBean} instance returned by
    045 * this class, or from the <code>Iterator</code> returned by the
    046 * <code>iterator()</code> method, is directly linked to the row that the
    047 * underlying result set is currently positioned at.  This has the following
    048 * implications:</p>
    049 * <ul>
    050 * <li>Once you retrieve a different {@link DynaBean} instance, you should
    051 *     no longer use any previous instance.</li>
    052 * <li>Changing the position of the underlying result set will change the
    053 *     data that the {@link DynaBean} references.</li>
    054 * <li>Once the underlying result set is closed, the {@link DynaBean}
    055 *     instance may no longer be used.</li>
    056 * </ul>
    057 *
    058 * <p>Any database data that you wish to utilize outside the context of the
    059 * current row of an open result set must be copied.  For example, you could
    060 * use the following code to create standalone copies of the information in
    061 * a result set:</p>
    062 * <pre>
    063 *   ArrayList results = new ArrayList(); // To hold copied list
    064 *   ResultSetDynaClass rsdc = ...;
    065 *   DynaProperty[] properties = rsdc.getDynaProperties();
    066 *   BasicDynaClass bdc =
    067 *     new BasicDynaClass("foo", BasicDynaBean.class,
    068 *                        rsdc.getDynaProperties());
    069 *   Iterator rows = rsdc.iterator();
    070 *   while (rows.hasNext()) {
    071 *     DynaBean oldRow = (DynaBean) rows.next();
    072 *     DynaBean newRow = bdc.newInstance();
    073 *     PropertyUtils.copyProperties(newRow, oldRow);
    074 *     results.add(newRow);
    075 *   }
    076 * </pre>
    077 *
    078 */
    079
    080public class ResultSetDynaClass extends JDBCDynaClass {
    081
    082    private static final long serialVersionUID = 1L;
    083
    084    /**
    085     * <p>The <code>ResultSet</code> we are wrapping.</p>
    086     */
    087    protected ResultSet resultSet;
    088
    089    /**
    090     * <p>Construct a new ResultSetDynaClass for the specified
    091     * <code>ResultSet</code>.  The property names corresponding
    092     * to column names in the result set will be lower cased.</p>
    093     *
    094     * @param resultSet The result set to be wrapped
    095     * @throws NullPointerException if <code>resultSet</code>
    096     *  is <code>null</code>
    097     * @throws SQLException if the metadata for this result set
    098     *  cannot be introspected
    099     */
    100    public ResultSetDynaClass(final ResultSet resultSet) throws SQLException {
    101
    102        this(resultSet, true);
    103
    104    }
    105
    106    /**
    107     * <p>Construct a new ResultSetDynaClass for the specified
    108     * <code>ResultSet</code>.  The property names corresponding
    109     * to the column names in the result set will be lower cased or not,
    110     * depending on the specified <code>lowerCase</code> value.</p>
    111     *
    112     * <p><strong>WARNING</strong> - If you specify <code>false</code>
    113     * for <code>lowerCase</code>, the returned property names will
    114     * exactly match the column names returned by your JDBC driver.
    115     * Because different drivers might return column names in different
    116     * cases, the property names seen by your application will vary
    117     * depending on which JDBC driver you are using.</p>
    118     *
    119     * @param resultSet The result set to be wrapped
    120     * @param lowerCase Should property names be lower cased?
    121     * @throws NullPointerException if <code>resultSet</code>
    122     *  is <code>null</code>
    123     * @throws SQLException if the metadata for this result set
    124     *  cannot be introspected
    125     */
    126    public ResultSetDynaClass(final ResultSet resultSet, final boolean lowerCase)
    127        throws SQLException {
    128
    129        this(resultSet, lowerCase, false);
    130
    131    }
    132
    133    /**
    134     * <p>Construct a new ResultSetDynaClass for the specified
    135     * <code>ResultSet</code>.  The property names corresponding
    136     * to the column names in the result set will be lower cased or not,
    137     * depending on the specified <code>lowerCase</code> value.</p>
    138     *
    139     * <p><strong>WARNING</strong> - If you specify <code>false</code>
    140     * for <code>lowerCase</code>, the returned property names will
    141     * exactly match the column names returned by your JDBC driver.
    142     * Because different drivers might return column names in different
    143     * cases, the property names seen by your application will vary
    144     * depending on which JDBC driver you are using.</p>
    145     *
    146     * @param resultSet The result set to be wrapped
    147     * @param lowerCase Should property names be lower cased?
    148     * @param useColumnLabel true if the column label should be used, otherwise false
    149     * @throws NullPointerException if <code>resultSet</code>
    150     *  is <code>null</code>
    151     * @throws SQLException if the metadata for this result set
    152     *  cannot be introspected
    153     * @since 1.8.3
    154     */
    155    public ResultSetDynaClass(final ResultSet resultSet, final boolean lowerCase, final boolean useColumnLabel)
    156        throws SQLException {
    157        this.resultSet = Objects.requireNonNull(resultSet, "resultSet");
    158        this.lowerCase = lowerCase;
    159        setUseColumnLabel(useColumnLabel);
    160        introspect(resultSet);
    161
    162    }
    163
    164    /**
    165     * Get a value from the {@link ResultSet} for the specified
    166     * property name.
    167     *
    168     * @param name The property name
    169     * @return The value
    170     * @throws SQLException if an error occurs
    171     * @since 1.8.0
    172     */
    173    public Object getObjectFromResultSet(final String name) throws SQLException {
    174        return getObject(getResultSet(), name);
    175    }
    176
    177    /**
    178     * <p>Return the result set we are wrapping.</p>
    179     */
    180    ResultSet getResultSet() {
    181
    182        return this.resultSet;
    183
    184    }
    185
    186    /**
    187     * <p>Return an <code>Iterator</code> of {@link DynaBean} instances for
    188     * each row of the wrapped <code>ResultSet</code>, in "forward" order.
    189     * Unless the underlying result set supports scrolling, this method
    190     * should be called only once.</p>
    191     * @return An <code>Iterator</code> of {@link DynaBean} instances
    192     */
    193    public Iterator<DynaBean> iterator() {
    194
    195        return new ResultSetIterator(this);
    196
    197    }
    198
    199    /**
    200     * <p>Loads the class of the given name which by default uses the class loader used
    201     * to load this library.
    202     * Dervations of this class could implement alternative class loading policies such as
    203     * using custom ClassLoader or using the Threads's context class loader etc.
    204     * </p>
    205     * @param className The name of the class to load
    206     * @return The loaded class
    207     * @throws SQLException if the class cannot be loaded
    208     */
    209    @Override
    210    protected Class<?> loadClass(final String className) throws SQLException {
    211
    212        try {
    213            return getClass().getClassLoader().loadClass(className);
    214        }
    215        catch (final Exception e) {
    216            throw new SQLException("Cannot load column class '" +
    217                                   className + "': " + e);
    218        }
    219    }
    220}