1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18
19 package org.apache.commons.beanutils;
20
21
22 import java.io.Serializable;
23 import java.lang.reflect.Constructor;
24 import java.lang.reflect.InvocationTargetException;
25 import java.util.HashMap;
26
27
28 /**
29 * <p>Minimal implementation of the <code>DynaClass</code> interface. Can be
30 * used as a convenience base class for more sophisticated implementations.</p> *
31 * <p><strong>IMPLEMENTATION NOTE</strong> - The <code>DynaBean</code>
32 * implementation class supplied to our constructor MUST have a one-argument
33 * constructor of its own that accepts a <code>DynaClass</code>. This is
34 * used to associate the DynaBean instance with this DynaClass.</p>
35 *
36 * @version $Id$
37 */
38
39 public class BasicDynaClass implements DynaClass, Serializable {
40
41
42 // ----------------------------------------------------------- Constructors
43
44
45 /**
46 * Construct a new BasicDynaClass with default parameters.
47 */
48 public BasicDynaClass() {
49
50 this(null, null, null);
51
52 }
53
54
55 /**
56 * Construct a new BasicDynaClass with the specified parameters.
57 *
58 * @param name Name of this DynaBean class
59 * @param dynaBeanClass The implementation class for new instances
60 */
61 public BasicDynaClass(final String name, final Class<?> dynaBeanClass) {
62
63 this(name, dynaBeanClass, null);
64
65 }
66
67
68 /**
69 * Construct a new BasicDynaClass with the specified parameters.
70 *
71 * @param name Name of this DynaBean class
72 * @param dynaBeanClass The implementation class for new intances
73 * @param properties Property descriptors for the supported properties
74 */
75 public BasicDynaClass(final String name, Class<?> dynaBeanClass,
76 final DynaProperty[] properties) {
77
78 super();
79 if (name != null) {
80 this.name = name;
81 }
82 if (dynaBeanClass == null) {
83 dynaBeanClass = BasicDynaBean.class;
84 }
85 setDynaBeanClass(dynaBeanClass);
86 if (properties != null) {
87 setProperties(properties);
88 }
89
90 }
91
92
93 // ----------------------------------------------------- Instance Variables
94
95
96 /**
97 * The constructor of the <code>dynaBeanClass</code> that we will use
98 * for creating new instances.
99 */
100 protected transient Constructor<?> constructor = null;
101
102
103 /**
104 * The method signature of the constructor we will use to create
105 * new DynaBean instances.
106 */
107 protected static Class<?>[] constructorTypes = { DynaClass.class };
108
109
110 /**
111 * The argument values to be passed to the constructore we will use
112 * to create new DynaBean instances.
113 */
114 protected Object[] constructorValues = { this };
115
116
117 /**
118 * The <code>DynaBean</code> implementation class we will use for
119 * creating new instances.
120 */
121 protected Class<?> dynaBeanClass = BasicDynaBean.class;
122
123
124 /**
125 * The "name" of this DynaBean class.
126 */
127 protected String name = this.getClass().getName();
128
129
130 /**
131 * The set of dynamic properties that are part of this DynaClass.
132 */
133 protected DynaProperty[] properties = new DynaProperty[0];
134
135
136 /**
137 * The set of dynamic properties that are part of this DynaClass,
138 * keyed by the property name. Individual descriptor instances will
139 * be the same instances as those in the <code>properties</code> list.
140 */
141 protected HashMap<String, DynaProperty> propertiesMap = new HashMap<String, DynaProperty>();
142
143
144 // ------------------------------------------------------ DynaClass Methods
145
146
147 /**
148 * Return the name of this DynaClass (analogous to the
149 * <code>getName()</code> method of <code>java.lang.Class</code), which
150 * allows the same <code>DynaClass</code> implementation class to support
151 * different dynamic classes, with different sets of properties.
152 *
153 * @return the name of the DynaClass
154 */
155 public String getName() {
156
157 return (this.name);
158
159 }
160
161
162 /**
163 * Return a property descriptor for the specified property, if it exists;
164 * otherwise, return <code>null</code>.
165 *
166 * @param name Name of the dynamic property for which a descriptor
167 * is requested
168 * @return The descriptor for the specified property
169 *
170 * @throws IllegalArgumentException if no property name is specified
171 */
172 public DynaProperty getDynaProperty(final String name) {
173
174 if (name == null) {
175 throw new IllegalArgumentException
176 ("No property name specified");
177 }
178 return propertiesMap.get(name);
179
180 }
181
182
183 /**
184 * <p>Return an array of <code>ProperyDescriptors</code> for the properties
185 * currently defined in this DynaClass. If no properties are defined, a
186 * zero-length array will be returned.</p>
187 *
188 * <p><strong>FIXME</strong> - Should we really be implementing
189 * <code>getBeanInfo()</code> instead, which returns property descriptors
190 * and a bunch of other stuff?</p>
191 *
192 * @return the set of properties for this DynaClass
193 */
194 public DynaProperty[] getDynaProperties() {
195
196 return (properties);
197
198 }
199
200
201 /**
202 * Instantiate and return a new DynaBean instance, associated
203 * with this DynaClass.
204 *
205 * @return A new <code>DynaBean</code> instance
206 * @throws IllegalAccessException if the Class or the appropriate
207 * constructor is not accessible
208 * @throws InstantiationException if this Class represents an abstract
209 * class, an array class, a primitive type, or void; or if instantiation
210 * fails for some other reason
211 */
212 public DynaBean newInstance()
213 throws IllegalAccessException, InstantiationException {
214
215 try {
216 // Refind the constructor after a deserialization (if needed)
217 if (constructor == null) {
218 setDynaBeanClass(this.dynaBeanClass);
219 }
220 // Invoke the constructor to create a new bean instance
221 return ((DynaBean) constructor.newInstance(constructorValues));
222 } catch (final InvocationTargetException e) {
223 throw new InstantiationException
224 (e.getTargetException().getMessage());
225 }
226
227 }
228
229
230 // --------------------------------------------------------- Public Methods
231
232
233 /**
234 * Return the Class object we will use to create new instances in the
235 * <code>newInstance()</code> method. This Class <strong>MUST</strong>
236 * implement the <code>DynaBean</code> interface.
237 *
238 * @return The class of the {@link DynaBean}
239 */
240 public Class<?> getDynaBeanClass() {
241
242 return (this.dynaBeanClass);
243
244 }
245
246
247 // ------------------------------------------------------ Protected Methods
248
249
250 /**
251 * Set the Class object we will use to create new instances in the
252 * <code>newInstance()</code> method. This Class <strong>MUST</strong>
253 * implement the <code>DynaBean</code> interface.
254 *
255 * @param dynaBeanClass The new Class object
256 *
257 * @throws IllegalArgumentException if the specified Class does not
258 * implement the <code>DynaBean</code> interface
259 */
260 protected void setDynaBeanClass(final Class<?> dynaBeanClass) {
261
262 // Validate the argument type specified
263 if (dynaBeanClass.isInterface()) {
264 throw new IllegalArgumentException
265 ("Class " + dynaBeanClass.getName() +
266 " is an interface, not a class");
267 }
268 if (!DynaBean.class.isAssignableFrom(dynaBeanClass)) {
269 throw new IllegalArgumentException
270 ("Class " + dynaBeanClass.getName() +
271 " does not implement DynaBean");
272 }
273
274 // Identify the Constructor we will use in newInstance()
275 try {
276 this.constructor = dynaBeanClass.getConstructor(constructorTypes);
277 } catch (final NoSuchMethodException e) {
278 throw new IllegalArgumentException
279 ("Class " + dynaBeanClass.getName() +
280 " does not have an appropriate constructor");
281 }
282 this.dynaBeanClass = dynaBeanClass;
283
284 }
285
286
287 /**
288 * Set the list of dynamic properties supported by this DynaClass.
289 *
290 * @param properties List of dynamic properties to be supported
291 */
292 protected void setProperties(final DynaProperty[] properties) {
293
294 this.properties = properties;
295 propertiesMap.clear();
296 for (DynaProperty propertie : properties) {
297 propertiesMap.put(propertie.getName(), propertie);
298 }
299
300 }
301
302
303 }