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
018
019 package org.apache.commons.beanutils;
020
021
022 import java.io.Serializable;
023 import java.sql.ResultSet;
024 import java.sql.SQLException;
025 import java.util.ArrayList;
026 import java.util.List;
027
028
029 /**
030 * <p>Implementation of {@link DynaClass} that creates an in-memory collection
031 * of {@link DynaBean}s representing the results of an SQL query. Once the
032 * {@link DynaClass} instance has been created, the JDBC <code>ResultSet</code>
033 * and <code>Statement</code> on which it is based can be closed, and the
034 * underlying <code>Connection</code> can be returned to its connection pool
035 * (if you are using one).</p>
036 *
037 * <p>The normal usage pattern is something like:</p>
038 * <pre>
039 * Connection conn = ...; // Acquire connection from pool
040 * Statement stmt = conn.createStatement();
041 * ResultSet rs = stmt.executeQuery("SELECT ...");
042 * RowSetDynaClass rsdc = new RowSetDynaClass(rs);
043 * rs.close();
044 * stmt.close();
045 * ...; // Return connection to pool
046 * List rows = rsdc.getRows();
047 * ...; // Process the rows as desired
048 * </pre>
049 *
050 * <p>Each column in the result set will be represented as a {@link DynaBean}
051 * property of the corresponding name (optionally forced to lower case
052 * for portability). There will be one {@link DynaBean} in the
053 * <code>List</code> returned by <code>getRows()</code> for each
054 * row in the original <code>ResultSet</code>.</p>
055 *
056 * <p>In general, instances of {@link RowSetDynaClass} can be serialized
057 * and deserialized, which will automatically include the list of
058 * {@link DynaBean}s representing the data content. The only exception
059 * to this rule would be when the underlying property values that were
060 * copied from the <code>ResultSet</code> originally cannot themselves
061 * be serialized. Therefore, a {@link RowSetDynaClass} makes a very
062 * convenient mechanism for transporting data sets to remote Java-based
063 * application components.</p>
064 *
065 * @author Craig R. McClanahan
066 * @version $Revision: 556233 $ $Date: 2007-07-14 07:37:06 +0100 (Sat, 14 Jul 2007) $
067 */
068
069 public class RowSetDynaClass extends JDBCDynaClass implements DynaClass, Serializable {
070
071
072 // ----------------------------------------------------- Instance variables
073
074 /**
075 * <p>Limits the size of the returned list. The call to
076 * <code>getRows()</code> will return at most limit number of rows.
077 * If less than or equal to 0, does not limit the size of the result.
078 */
079 protected int limit = -1;
080
081 /**
082 * <p>The list of {@link DynaBean}s representing the contents of
083 * the original <code>ResultSet</code> on which this
084 * {@link RowSetDynaClass} was based.</p>
085 */
086 protected List rows = new ArrayList();
087
088 // ----------------------------------------------------------- Constructors
089
090
091 /**
092 * <p>Construct a new {@link RowSetDynaClass} for the specified
093 * <code>ResultSet</code>. The property names corresponding
094 * to column names in the result set will be lower cased.</p>
095 *
096 * @param resultSet The result set to be wrapped
097 *
098 * @exception NullPointerException if <code>resultSet</code>
099 * is <code>null</code>
100 * @exception SQLException if the metadata for this result set
101 * cannot be introspected
102 */
103 public RowSetDynaClass(ResultSet resultSet) throws SQLException {
104
105 this(resultSet, true, -1);
106
107 }
108
109 /**
110 * <p>Construct a new {@link RowSetDynaClass} for the specified
111 * <code>ResultSet</code>. The property names corresponding
112 * to column names in the result set will be lower cased.</p>
113 *
114 * If <code>limit</code> is not less than 0, max <code>limit</code>
115 * number of rows will be copied into the list.
116 *
117 * @param resultSet The result set to be wrapped
118 * @param limit The maximum for the size of the result.
119 *
120 * @exception NullPointerException if <code>resultSet</code>
121 * is <code>null</code>
122 * @exception SQLException if the metadata for this result set
123 * cannot be introspected
124 */
125 public RowSetDynaClass(ResultSet resultSet, int limit) throws SQLException {
126
127 this(resultSet, true, limit);
128
129 }
130
131
132 /**
133 * <p>Construct a new {@link RowSetDynaClass} for the specified
134 * <code>ResultSet</code>. The property names corresponding
135 * to the column names in the result set will be lower cased or not,
136 * depending on the specified <code>lowerCase</code> value.</p>
137 *
138 * If <code>limit</code> is not less than 0, max <code>limit</code>
139 * number of rows will be copied into the resultset.
140 *
141 *
142 * @param resultSet The result set to be wrapped
143 * @param lowerCase Should property names be lower cased?
144 *
145 * @exception NullPointerException if <code>resultSet</code>
146 * is <code>null</code>
147 * @exception SQLException if the metadata for this result set
148 * cannot be introspected
149 */
150 public RowSetDynaClass(ResultSet resultSet, boolean lowerCase)
151 throws SQLException {
152 this(resultSet, lowerCase, -1);
153
154 }
155
156 /**
157 * <p>Construct a new {@link RowSetDynaClass} for the specified
158 * <code>ResultSet</code>. The property names corresponding
159 * to the column names in the result set will be lower cased or not,
160 * depending on the specified <code>lowerCase</code> value.</p>
161 *
162 * <p><strong>WARNING</strong> - If you specify <code>false</code>
163 * for <code>lowerCase</code>, the returned property names will
164 * exactly match the column names returned by your JDBC driver.
165 * Because different drivers might return column names in different
166 * cases, the property names seen by your application will vary
167 * depending on which JDBC driver you are using.</p>
168 *
169 * @param resultSet The result set to be wrapped
170 * @param lowerCase Should property names be lower cased?
171 * @param limit Maximum limit for the <code>List</code> of {@link DynaBean}
172 *
173 * @exception NullPointerException if <code>resultSet</code>
174 * is <code>null</code>
175 * @exception SQLException if the metadata for this result set
176 * cannot be introspected
177 */
178 public RowSetDynaClass(ResultSet resultSet, boolean lowerCase, int limit)
179 throws SQLException {
180
181 if (resultSet == null) {
182 throw new NullPointerException();
183 }
184 this.lowerCase = lowerCase;
185 this.limit = limit;
186 introspect(resultSet);
187 copy(resultSet);
188
189 }
190
191 /**
192 * <p>Return a <code>List</code> containing the {@link DynaBean}s that
193 * represent the contents of each <code>Row</code> from the
194 * <code>ResultSet</code> that was the basis of this
195 * {@link RowSetDynaClass} instance. These {@link DynaBean}s are
196 * disconnected from the database itself, so there is no problem with
197 * modifying the contents of the list, or the values of the properties
198 * of these {@link DynaBean}s. However, it is the application's
199 * responsibility to persist any such changes back to the database,
200 * if it so desires.</p>
201 *
202 * @return A <code>List</code> of {@link DynaBean} instances
203 */
204 public List getRows() {
205
206 return (this.rows);
207
208 }
209
210
211 // ------------------------------------------------------ Protected Methods
212
213
214 /**
215 * <p>Copy the column values for each row in the specified
216 * <code>ResultSet</code> into a newly created {@link DynaBean}, and add
217 * this bean to the list of {@link DynaBean}s that will later by
218 * returned by a call to <code>getRows()</code>.</p>
219 *
220 * @param resultSet The <code>ResultSet</code> whose data is to be
221 * copied
222 *
223 * @exception SQLException if an error is encountered copying the data
224 */
225 protected void copy(ResultSet resultSet) throws SQLException {
226
227 int cnt = 0;
228 while (resultSet.next() && (limit < 0 || cnt++ < limit) ) {
229 DynaBean bean = createDynaBean();
230 for (int i = 0; i < properties.length; i++) {
231 String name = properties[i].getName();
232 Object value = getObject(resultSet, name);
233 bean.set(name, value);
234 }
235 rows.add(bean);
236 }
237
238 }
239
240
241 /**
242 * <p>Create and return a new {@link DynaBean} instance to be used for
243 * representing a row in the underlying result set.</p>
244 *
245 * @return A new <code>DynaBean</code> instance
246 */
247 protected DynaBean createDynaBean() {
248
249 return (new BasicDynaBean(this));
250
251 }
252
253
254 }