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    
019    package org.apache.commons.beanutils;
020    
021    
022    import java.io.IOException;
023    import java.io.Serializable;
024    import java.io.ObjectOutputStream;
025    import java.io.ObjectInputStream;
026    import java.io.StreamCorruptedException;
027    import java.util.List;
028    import java.util.Map;
029    
030    
031    /**
032     * <p>The metadata describing an individual property of a DynaBean.</p>
033     *
034     * <p>The meta contains an <em>optional</em> content type property ({@link #getContentType})
035     * for use by mapped and iterated properties. 
036     * A mapped or iterated property may choose to indicate the type it expects.
037     * The DynaBean implementation may choose to enforce this type on its entries.
038     * Alternatively, an implementatin may choose to ignore this property.
039     * All keys for maps must be of type String so no meta data is needed for map keys.</p>
040     *
041     * @author Craig R. McClanahan
042     * @version $Revision: 555824 $ $Date: 2007-07-13 01:27:15 +0100 (Fri, 13 Jul 2007) $
043     */
044    
045    public class DynaProperty implements Serializable {
046    
047        // ----------------------------------------------------------- Constants
048        
049        /*
050         * There are issues with serializing primitive class types on certain JVM versions
051         * (including java 1.3).
052         * This class uses a custom serialization implementation that writes an integer
053         * for these primitive class.
054         * This list of constants are the ones used in serialization.
055         * If these values are changed, then older versions will no longer be read correctly
056         */
057        private static final int BOOLEAN_TYPE = 1;
058        private static final int BYTE_TYPE = 2;
059        private static final int CHAR_TYPE = 3;
060        private static final int DOUBLE_TYPE = 4;
061        private static final int FLOAT_TYPE = 5;
062        private static final int INT_TYPE = 6;
063        private static final int LONG_TYPE = 7;
064        private static final int SHORT_TYPE = 8;
065        
066    
067        // ----------------------------------------------------------- Constructors
068    
069    
070        /**
071         * Construct a property that accepts any data type.
072         *
073         * @param name Name of the property being described
074         */
075        public DynaProperty(String name) {
076    
077            this(name, Object.class);
078    
079        }
080    
081    
082        /**
083         * Construct a property of the specified data type.
084         *
085         * @param name Name of the property being described
086         * @param type Java class representing the property data type
087         */
088        public DynaProperty(String name, Class type) {
089    
090            super();
091            this.name = name;
092            this.type = type;
093            if (type != null && type.isArray()) {
094                this.contentType = type.getComponentType();
095            }
096    
097        }
098        
099        /**
100         * Construct an indexed or mapped <code>DynaProperty</code> that supports (pseudo)-introspection
101         * of the content type.
102         *
103         * @param name Name of the property being described
104         * @param type Java class representing the property data type
105         * @param contentType Class that all indexed or mapped elements are instances of
106         */
107        public DynaProperty(String name, Class type, Class contentType) {
108    
109            super();
110            this.name = name;
111            this.type = type;
112            this.contentType = contentType;
113            
114        }
115    
116        // ------------------------------------------------------------- Properties
117    
118        /** Property name */
119        protected String name = null;
120        /**
121         * Get the name of this property.
122         * @return the name of the property
123         */
124        public String getName() {
125            return (this.name);
126        }
127        
128        /** Property type */
129        protected transient Class type = null;
130        /**
131         * <p>Gets the Java class representing the data type of the underlying property
132         * values.</p>
133         * 
134         * <p>There are issues with serializing primitive class types on certain JVM versions
135         * (including java 1.3).
136         * Therefore, this field <strong>must not be serialized using the standard methods</strong>.</p>
137         * 
138         * <p><strong>Please leave this field as <code>transient</code></strong></p>
139         *
140         * @return the property type
141         */
142        public Class getType() {
143            return (this.type);
144        }
145        
146        
147        /** The <em>(optional)</em> type of content elements for indexed <code>DynaProperty</code> */
148        protected transient Class contentType;
149        /**
150         * Gets the <em>(optional)</em> type of the indexed content for <code>DynaProperty</code>'s
151         * that support this feature.
152         *
153         * <p>There are issues with serializing primitive class types on certain JVM versions
154         * (including java 1.3).
155         * Therefore, this field <strong>must not be serialized using the standard methods</strong>.</p>
156         *
157         * @return the Class for the content type if this is an indexed <code>DynaProperty</code> 
158         * and this feature is supported. Otherwise null.
159         */
160        public Class getContentType() {
161            return contentType;
162        }
163        
164        // --------------------------------------------------------- Public Methods
165    
166    
167        /**
168         * Does this property represent an indexed value (ie an array or List)?
169         *
170         * @return <code>true</code> if the property is indexed (i.e. is a List or
171         * array), otherwise <code>false</code>
172         */
173        public boolean isIndexed() {
174    
175            if (type == null) {
176                return (false);
177            } else if (type.isArray()) {
178                return (true);
179            } else if (List.class.isAssignableFrom(type)) {
180                return (true);
181            } else {
182                return (false);
183            }
184    
185        }
186    
187    
188        /**
189         * Does this property represent a mapped value (ie a Map)?
190         *
191         * @return <code>true</code> if the property is a Map
192         * otherwise <code>false</code>
193         */
194        public boolean isMapped() {
195    
196            if (type == null) {
197                return (false);
198            } else {
199                return (Map.class.isAssignableFrom(type));
200            }
201    
202        }
203    
204        /**
205         * Checks this instance against the specified Object for equality. Overrides the
206         * default refererence test for equality provided by {@link java.lang.Object#equals(Object)}  
207         * @param obj The object to compare to
208         * @return <code>true</code> if object is a dyna property with the same name
209         * type and content type, otherwise <code>false</code>
210         */
211        public boolean equals(final Object obj) {
212    
213            boolean result = false;
214    
215            result = (obj == this);
216    
217            if ((!result) && obj instanceof DynaProperty) {
218                final DynaProperty that = (DynaProperty) obj;
219                result = 
220                   ((this.name == null) ? (that.name == null) : (this.name.equals(that.name))) &&
221                   ((this.type == null) ? (that.type == null) : (this.type.equals(that.type))) &&
222                   ((this.contentType == null) ? (that.contentType == null) : (this.contentType.equals(that.contentType)));
223            }
224    
225            return result;
226        }
227    
228        /**
229         * @return the hashcode for this dyna property
230         * @see java.lang.Object#hashCode
231         */
232        public int hashCode() {
233    
234           int result = 1;
235           
236           result = result * 31 + ((name == null) ? 0 : name.hashCode());
237           result = result * 31 + ((type == null) ? 0 : type.hashCode());
238           result = result * 31 + ((contentType == null) ? 0 : contentType.hashCode());
239    
240           return result;
241        }
242    
243        /**
244         * Return a String representation of this Object.
245         * @return a String representation of the dyna property
246         */
247        public String toString() {
248    
249            StringBuffer sb = new StringBuffer("DynaProperty[name=");
250            sb.append(this.name);
251            sb.append(",type=");
252            sb.append(this.type);
253            if (isMapped() || isIndexed()) {
254                sb.append(" <").append(this.contentType).append(">");
255            }
256            sb.append("]");
257            return (sb.toString());
258    
259        }
260    
261        // --------------------------------------------------------- Serialization helper methods
262        
263        /**
264         * Writes this object safely.
265         * There are issues with serializing primitive class types on certain JVM versions
266         * (including java 1.3).
267         * This method provides a workaround.
268         */
269        private void writeObject(ObjectOutputStream out) throws IOException {
270            
271            writeAnyClass(this.type,out);
272            
273            if (isMapped() || isIndexed()) {
274                writeAnyClass(this.contentType,out);
275            }
276            
277            // write out other values
278            out.defaultWriteObject();
279        }
280    
281        /**
282         * Write a class using safe encoding to workaround java 1.3 serialization bug.
283         */
284        private void writeAnyClass(Class clazz, ObjectOutputStream out) throws IOException {
285            // safely write out any class
286            int primitiveType = 0;
287            if (Boolean.TYPE.equals(clazz)) {
288                primitiveType = BOOLEAN_TYPE;
289            } else if (Byte.TYPE.equals(clazz)) {
290                primitiveType = BYTE_TYPE;
291            } else if (Character.TYPE.equals(clazz)) {
292                primitiveType = CHAR_TYPE;
293            } else if (Double.TYPE.equals(clazz)) {
294                primitiveType = DOUBLE_TYPE;
295            } else if (Float.TYPE.equals(clazz)) {
296                primitiveType = FLOAT_TYPE;
297            } else if (Integer.TYPE.equals(clazz)) {
298                primitiveType = INT_TYPE;
299            } else if (Long.TYPE.equals(clazz)) {
300                primitiveType = LONG_TYPE;
301            } else if (Short.TYPE.equals(clazz)) {
302                primitiveType = SHORT_TYPE;
303            }
304            
305            if (primitiveType == 0) {
306                // then it's not a primitive type
307                out.writeBoolean(false);
308                out.writeObject(clazz);
309            } else {
310                // we'll write out a constant instead
311                out.writeBoolean(true);
312                out.writeInt(primitiveType);
313            }
314        }
315        
316        /**
317         * Reads field values for this object safely.
318         * There are issues with serializing primitive class types on certain JVM versions
319         * (including java 1.3).
320         * This method provides a workaround.
321         *
322         * @throws StreamCorruptedException when the stream data values are outside expected range 
323         */
324        private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
325            
326            this.type = readAnyClass(in);
327            
328            if (isMapped() || isIndexed()) {
329                this.contentType = readAnyClass(in);
330            }
331            
332            // read other values
333            in.defaultReadObject();
334        }
335        
336    
337        /**
338         * Reads a class using safe encoding to workaround java 1.3 serialization bug.
339         */
340        private Class readAnyClass(ObjectInputStream in) throws IOException, ClassNotFoundException {
341            // read back type class safely 
342            if (in.readBoolean()) {
343                // it's a type constant
344                switch (in.readInt()) {
345                
346                    case BOOLEAN_TYPE: return   Boolean.TYPE;
347                    case BYTE_TYPE:    return      Byte.TYPE;
348                    case CHAR_TYPE:    return Character.TYPE;
349                    case DOUBLE_TYPE:  return    Double.TYPE;
350                    case FLOAT_TYPE:   return     Float.TYPE;
351                    case INT_TYPE:     return   Integer.TYPE;
352                    case LONG_TYPE:    return      Long.TYPE;
353                    case SHORT_TYPE:   return     Short.TYPE;
354                    default:
355                        // something's gone wrong
356                        throw new StreamCorruptedException(
357                            "Invalid primitive type. "
358                            + "Check version of beanutils used to serialize is compatible.");
359    
360                }
361                  
362            } else {
363                // it's another class
364                return ((Class) in.readObject());
365            }
366        }
367    }