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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   * @author Craig McClanahan
37   * @version $Revision: 556229 $ $Date: 2007-07-14 07:11:19 +0100 (Sat, 14 Jul 2007) $
38   */
39  
40  public class BasicDynaClass implements DynaClass, Serializable {
41  
42  
43      // ----------------------------------------------------------- Constructors
44  
45  
46      /***
47       * Construct a new BasicDynaClass with default parameters.
48       */
49      public BasicDynaClass() {
50  
51          this(null, null, null);
52  
53      }
54  
55  
56      /***
57       * Construct a new BasicDynaClass with the specified parameters.
58       *
59       * @param name Name of this DynaBean class
60       * @param dynaBeanClass The implementation class for new instances
61       */
62      public BasicDynaClass(String name, Class dynaBeanClass) {
63  
64          this(name, dynaBeanClass, null);
65  
66      }
67  
68  
69      /***
70       * Construct a new BasicDynaClass with the specified parameters.
71       *
72       * @param name Name of this DynaBean class
73       * @param dynaBeanClass The implementation class for new intances
74       * @param properties Property descriptors for the supported properties
75       */
76      public BasicDynaClass(String name, Class dynaBeanClass,
77                            DynaProperty[] properties) {
78  
79          super();
80          if (name != null) {
81              this.name = name;
82          }
83          if (dynaBeanClass == null) {
84              dynaBeanClass = BasicDynaBean.class;
85          }
86          setDynaBeanClass(dynaBeanClass);
87          if (properties != null) {
88              setProperties(properties);
89          }
90  
91      }
92  
93  
94      // ----------------------------------------------------- Instance Variables
95  
96  
97      /***
98       * The constructor of the <code>dynaBeanClass</code> that we will use
99       * for creating new instances.
100      */
101     protected transient Constructor constructor = null;
102 
103 
104     /***
105      * The method signature of the constructor we will use to create
106      * new DynaBean instances.
107      */
108     protected static Class[] constructorTypes = { DynaClass.class };
109 
110 
111     /***
112      * The argument values to be passed to the constructore we will use
113      * to create new DynaBean instances.
114      */
115     protected Object[] constructorValues = { this };
116 
117 
118     /***
119      * The <code>DynaBean</code> implementation class we will use for
120      * creating new instances.
121      */
122     protected Class dynaBeanClass = BasicDynaBean.class;
123 
124 
125     /***
126      * The "name" of this DynaBean class.
127      */
128     protected String name = this.getClass().getName();
129 
130 
131     /***
132      * The set of dynamic properties that are part of this DynaClass.
133      */
134     protected DynaProperty[] properties = new DynaProperty[0];
135 
136 
137     /***
138      * The set of dynamic properties that are part of this DynaClass,
139      * keyed by the property name.  Individual descriptor instances will
140      * be the same instances as those in the <code>properties</code> list.
141      */
142     protected HashMap propertiesMap = new HashMap();
143 
144 
145     // ------------------------------------------------------ DynaClass Methods
146 
147 
148     /***
149      * Return the name of this DynaClass (analogous to the
150      * <code>getName()</code> method of <code>java.lang.Class</code), which
151      * allows the same <code>DynaClass</code> implementation class to support
152      * different dynamic classes, with different sets of properties.
153      *
154      * @return the name of the DynaClass
155      */
156     public String getName() {
157 
158         return (this.name);
159 
160     }
161 
162 
163     /***
164      * Return a property descriptor for the specified property, if it exists;
165      * otherwise, return <code>null</code>.
166      *
167      * @param name Name of the dynamic property for which a descriptor
168      *  is requested
169      * @return The descriptor for the specified property
170      *
171      * @exception IllegalArgumentException if no property name is specified
172      */
173     public DynaProperty getDynaProperty(String name) {
174 
175         if (name == null) {
176             throw new IllegalArgumentException
177                     ("No property name specified");
178         }
179         return ((DynaProperty) propertiesMap.get(name));
180 
181     }
182 
183 
184     /***
185      * <p>Return an array of <code>ProperyDescriptors</code> for the properties
186      * currently defined in this DynaClass.  If no properties are defined, a
187      * zero-length array will be returned.</p>
188      *
189      * <p><strong>FIXME</strong> - Should we really be implementing
190      * <code>getBeanInfo()</code> instead, which returns property descriptors
191      * and a bunch of other stuff?</p>
192      *
193      * @return the set of properties for this DynaClass
194      */
195     public DynaProperty[] getDynaProperties() {
196 
197         return (properties);
198 
199     }
200 
201 
202     /***
203      * Instantiate and return a new DynaBean instance, associated
204      * with this DynaClass.
205      *
206      * @return A new <code>DynaBean</code> instance
207      * @exception IllegalAccessException if the Class or the appropriate
208      *  constructor is not accessible
209      * @exception InstantiationException if this Class represents an abstract
210      *  class, an array class, a primitive type, or void; or if instantiation
211      *  fails for some other reason
212      */
213     public DynaBean newInstance()
214             throws IllegalAccessException, InstantiationException {
215 
216         try {
217             // Refind the constructor after a deserialization (if needed)
218             if (constructor == null) {
219                 setDynaBeanClass(this.dynaBeanClass);
220             }
221             // Invoke the constructor to create a new bean instance
222             return ((DynaBean) constructor.newInstance(constructorValues));
223         } catch (InvocationTargetException e) {
224             throw new InstantiationException
225                     (e.getTargetException().getMessage());
226         }
227 
228     }
229 
230 
231     // --------------------------------------------------------- Public Methods
232 
233 
234     /***
235      * Return the Class object we will use to create new instances in the
236      * <code>newInstance()</code> method.  This Class <strong>MUST</strong>
237      * implement the <code>DynaBean</code> interface.
238      *
239      * @return The class of the {@link DynaBean}
240      */
241     public Class getDynaBeanClass() {
242 
243         return (this.dynaBeanClass);
244 
245     }
246 
247 
248     // ------------------------------------------------------ Protected Methods
249 
250 
251     /***
252      * Set the Class object we will use to create new instances in the
253      * <code>newInstance()</code> method.  This Class <strong>MUST</strong>
254      * implement the <code>DynaBean</code> interface.
255      *
256      * @param dynaBeanClass The new Class object
257      *
258      * @exception IllegalArgumentException if the specified Class does not
259      *  implement the <code>DynaBean</code> interface
260      */
261     protected void setDynaBeanClass(Class dynaBeanClass) {
262 
263         // Validate the argument type specified
264         if (dynaBeanClass.isInterface()) {
265             throw new IllegalArgumentException
266                     ("Class " + dynaBeanClass.getName() +
267                     " is an interface, not a class");
268         }
269         if (!DynaBean.class.isAssignableFrom(dynaBeanClass)) {
270             throw new IllegalArgumentException
271                     ("Class " + dynaBeanClass.getName() +
272                     " does not implement DynaBean");
273         }
274 
275         // Identify the Constructor we will use in newInstance()
276         try {
277             this.constructor = dynaBeanClass.getConstructor(constructorTypes);
278         } catch (NoSuchMethodException e) {
279             throw new IllegalArgumentException
280                     ("Class " + dynaBeanClass.getName() +
281                     " does not have an appropriate constructor");
282         }
283         this.dynaBeanClass = dynaBeanClass;
284 
285     }
286 
287 
288     /***
289      * Set the list of dynamic properties supported by this DynaClass.
290      *
291      * @param properties List of dynamic properties to be supported
292      */
293     protected void setProperties(DynaProperty[] properties) {
294 
295         this.properties = properties;
296         propertiesMap.clear();
297         for (int i = 0; i < properties.length; i++) {
298             propertiesMap.put(properties[i].getName(), properties[i]);
299         }
300 
301     }
302 
303 
304 }