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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   * @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 }