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
019package org.apache.commons.beanutils;
020
021
022import java.io.Serializable;
023import java.lang.reflect.Constructor;
024import java.lang.reflect.InvocationTargetException;
025import java.util.HashMap;
026
027
028/**
029 * <p>Minimal implementation of the <code>DynaClass</code> interface.  Can be
030 * used as a convenience base class for more sophisticated implementations.</p> *
031 * <p><strong>IMPLEMENTATION NOTE</strong> - The <code>DynaBean</code>
032 * implementation class supplied to our constructor MUST have a one-argument
033 * constructor of its own that accepts a <code>DynaClass</code>.  This is
034 * used to associate the DynaBean instance with this DynaClass.</p>
035 *
036 * @author Craig McClanahan
037 * @version $Revision: 926529 $ $Date: 2010-03-23 11:44:24 +0000 (Tue, 23 Mar 2010) $
038 */
039
040public class BasicDynaClass implements DynaClass, Serializable {
041
042
043    // ----------------------------------------------------------- Constructors
044
045
046    /**
047     * Construct a new BasicDynaClass with default parameters.
048     */
049    public BasicDynaClass() {
050
051        this(null, null, null);
052
053    }
054
055
056    /**
057     * Construct a new BasicDynaClass with the specified parameters.
058     *
059     * @param name Name of this DynaBean class
060     * @param dynaBeanClass The implementation class for new instances
061     */
062    public BasicDynaClass(String name, Class dynaBeanClass) {
063
064        this(name, dynaBeanClass, null);
065
066    }
067
068
069    /**
070     * Construct a new BasicDynaClass with the specified parameters.
071     *
072     * @param name Name of this DynaBean class
073     * @param dynaBeanClass The implementation class for new intances
074     * @param properties Property descriptors for the supported properties
075     */
076    public BasicDynaClass(String name, Class dynaBeanClass,
077                          DynaProperty[] properties) {
078
079        super();
080        if (name != null) {
081            this.name = name;
082        }
083        if (dynaBeanClass == null) {
084            dynaBeanClass = BasicDynaBean.class;
085        }
086        setDynaBeanClass(dynaBeanClass);
087        if (properties != null) {
088            setProperties(properties);
089        }
090
091    }
092
093
094    // ----------------------------------------------------- Instance Variables
095
096
097    /**
098     * The constructor of the <code>dynaBeanClass</code> that we will use
099     * 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}