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18 package org.apache.commons.beanutils;
19
20
21 import java.io.Serializable;
22 import java.lang.reflect.Constructor;
23 import java.lang.reflect.InvocationTargetException;
24 import java.util.HashMap;
25
26
27 /**
28 * <p>Minimal implementation of the <code>DynaClass</code> interface. Can be
29 * used as a convenience base class for more sophisticated implementations.</p> *
30 * <p><strong>IMPLEMENTATION NOTE</strong> - The <code>DynaBean</code>
31 * implementation class supplied to our constructor MUST have a one-argument
32 * constructor of its own that accepts a <code>DynaClass</code>. This is
33 * used to associate the DynaBean instance with this DynaClass.</p>
34 *
35 * @author Craig McClanahan
36 * @version $Revision: 1.11 $ $Date: 2004/02/28 13:18:33 $
37 */
38
39 public class BasicDynaClass implements DynaClass, Serializable {
40
41
42
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(String name, 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(String name, Class dynaBeanClass,
76 DynaProperty properties[]) {
77
78 super();
79 if (name != null)
80 this.name = name;
81 if (dynaBeanClass == null)
82 dynaBeanClass = BasicDynaBean.class;
83 setDynaBeanClass(dynaBeanClass);
84 if (properties != null)
85 setProperties(properties);
86
87 }
88
89
90
91
92
93 /**
94 * The constructor of the <code>dynaBeanClass</code> that we will use
95 * for creating new instances.
96 */
97 protected transient Constructor constructor = null;
98
99
100 /**
101 * The method signature of the constructor we will use to create
102 * new DynaBean instances.
103 */
104 protected static Class constructorTypes[] = { DynaClass.class };
105
106
107 /**
108 * The argument values to be passed to the constructore we will use
109 * to create new DynaBean instances.
110 */
111 protected Object constructorValues[] = { this };
112
113
114 /**
115 * The <code>DynaBean</code> implementation class we will use for
116 * creating new instances.
117 */
118 protected Class dynaBeanClass = BasicDynaBean.class;
119
120
121 /**
122 * The "name" of this DynaBean class.
123 */
124 protected String name = this.getClass().getName();
125
126
127 /**
128 * The set of dynamic properties that are part of this DynaClass.
129 */
130 protected DynaProperty properties[] = new DynaProperty[0];
131
132
133 /**
134 * The set of dynamic properties that are part of this DynaClass,
135 * keyed by the property name. Individual descriptor instances will
136 * be the same instances as those in the <code>properties</code> list.
137 */
138 protected HashMap propertiesMap = new HashMap();
139
140
141
142
143
144 /**
145 * Return the name of this DynaClass (analogous to the
146 * <code>getName()</code> method of <code>java.lang.Class</code), which
147 * allows the same <code>DynaClass</code> implementation class to support
148 * different dynamic classes, with different sets of properties.
149 */
150 public String getName() {
151
152 return (this.name);
153
154 }
155
156
157 /**
158 * Return a property descriptor for the specified property, if it exists;
159 * otherwise, return <code>null</code>.
160 *
161 * @param name Name of the dynamic property for which a descriptor
162 * is requested
163 *
164 * @exception IllegalArgumentException if no property name is specified
165 */
166 public DynaProperty getDynaProperty(String name) {
167
168 if (name == null) {
169 throw new IllegalArgumentException
170 ("No property name specified");
171 }
172 return ((DynaProperty) propertiesMap.get(name));
173
174 }
175
176
177 /**
178 * <p>Return an array of <code>ProperyDescriptors</code> for the properties
179 * currently defined in this DynaClass. If no properties are defined, a
180 * zero-length array will be returned.</p>
181 *
182 * <p><strong>FIXME</strong> - Should we really be implementing
183 * <code>getBeanInfo()</code> instead, which returns property descriptors
184 * and a bunch of other stuff?</p>
185 */
186 public DynaProperty[] getDynaProperties() {
187
188 return (properties);
189
190 }
191
192
193 /**
194 * Instantiate and return a new DynaBean instance, associated
195 * with this DynaClass.
196 *
197 * @exception IllegalAccessException if the Class or the appropriate
198 * constructor is not accessible
199 * @exception InstantiationException if this Class represents an abstract
200 * class, an array class, a primitive type, or void; or if instantiation
201 * fails for some other reason
202 */
203 public DynaBean newInstance()
204 throws IllegalAccessException, InstantiationException {
205
206 try {
207
208 if (constructor == null) {
209 setDynaBeanClass(this.dynaBeanClass);
210 }
211
212 return ((DynaBean) constructor.newInstance(constructorValues));
213 } catch (InvocationTargetException e) {
214 throw new InstantiationException
215 (e.getTargetException().getMessage());
216 }
217
218 }
219
220
221
222
223
224 /**
225 * Return the Class object we will use to create new instances in the
226 * <code>newInstance()</code> method. This Class <strong>MUST</strong>
227 * implement the <code>DynaBean</code> interface.
228 */
229 public Class getDynaBeanClass() {
230
231 return (this.dynaBeanClass);
232
233 }
234
235
236
237
238
239 /**
240 * Set the Class object we will use to create new instances in the
241 * <code>newInstance()</code> method. This Class <strong>MUST</strong>
242 * implement the <code>DynaBean</code> interface.
243 *
244 * @param dynaBeanClass The new Class object
245 *
246 * @exception IllegalArgumentException if the specified Class does not
247 * implement the <code>DynaBean</code> interface
248 */
249 protected void setDynaBeanClass(Class dynaBeanClass) {
250
251
252 if (dynaBeanClass.isInterface())
253 throw new IllegalArgumentException
254 ("Class " + dynaBeanClass.getName() +
255 " is an interface, not a class");
256 if (!DynaBean.class.isAssignableFrom(dynaBeanClass))
257 throw new IllegalArgumentException
258 ("Class " + dynaBeanClass.getName() +
259 " does not implement DynaBean");
260
261
262 try {
263 this.constructor = dynaBeanClass.getConstructor(constructorTypes);
264 } catch (NoSuchMethodException e) {
265 throw new IllegalArgumentException
266 ("Class " + dynaBeanClass.getName() +
267 " does not have an appropriate constructor");
268 }
269 this.dynaBeanClass = dynaBeanClass;
270
271 }
272
273
274 /**
275 * Set the list of dynamic properties supported by this DynaClass.
276 *
277 * @param properties List of dynamic properties to be supported
278 */
279 protected void setProperties(DynaProperty properties[]) {
280
281 this.properties = properties;
282 propertiesMap.clear();
283 for (int i = 0; i < properties.length; i++) {
284 propertiesMap.put(properties[i].getName(), properties[i]);
285 }
286
287 }
288
289
290 }