JBossObject


1   /*
2     * JBoss, Home of Professional Open Source
3     * Copyright 2005, JBoss Inc., and individual contributors as indicated
4     * by the @authors tag. See the copyright.txt in the distribution for a
5     * full listing of individual contributors.
6     *
7     * This is free software; you can redistribute it and/or modify it
8     * under the terms of the GNU Lesser General Public License as
9     * published by the Free Software Foundation; either version 2.1 of
10    * the License, or (at your option) any later version.
11    *
12    * This software is distributed in the hope that it will be useful,
13    * but WITHOUT ANY WARRANTY; without even the implied warranty of
14    * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15    * Lesser General Public License for more details.
16    *
17    * You should have received a copy of the GNU Lesser General Public
18    * License along with this software; if not, write to the Free
19    * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
20    * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
21    */
22  package org.jboss.util;
23  
24  import java.lang.ref.SoftReference  ;
25  import java.util.Collection  ;
26  import java.util.Iterator  ;
27  
28  import org.jboss.logging.Logger;
29  
30  /**
31   * Utility Class
32   * 
33   * Utility Class that provides a Logger instance (log) and
34   * caching of toString() and hashCode() values.
35   * 
36   * You most probably want to override the method that
37   * comes from JBossInterface:
38   * 
39   *    public void toShortString(StringBuffer buffer)
40   *
41   * to append to the buffer the key class properties, and
42   * also override the following methods to provide the
43   * hashCode and the class properties that should be cached:
44   * 
45   *    protected void toString(StringBuffer buffer)
46   *    protected int getHashCode()
47   * 
48   * Cached values can be flushed using flushJBossObjectCache()
49   * 
50   * Caching can be disabled by simply overriding toString()
51   * and hashCode(), or returning false from methods:
52   * 
53   *    protected boolean cacheToString()
54   *    protected boolean cacheGetHashCode()  
55   * 
56   * @author <a HREF="adrian@jboss.com">Adrian Brock</a>
57   * @version $Revision: 1958 $
58   */
59  public class JBossObject implements JBossInterface
60  {
61     /** The log */
62     protected Logger log;
63     
64     /** Cached toString */
65     protected transient SoftReference   toString;
66     
67     /** Cached hashCode */
68     protected transient int hashCode = Integer.MIN_VALUE;
69  
70     /**
71      * Safe equality check
72      * 
73      * @param one an object
74      * @param two another object
75      */
76     public static boolean equals(Object   one, Object   two)
77     {
78        if (one == null && two != null)
79           return false;
80        if (one != null && one.equals(two) == false)
81           return false;
82        return true;
83     }
84  
85     /**
86      * Safe inequality check
87      * 
88      * @param one an object
89      * @param two another object
90      */
91     public static boolean notEqual(Object   one, Object   two)
92     {
93        return equals(one, two) == false;
94     }
95  
96     /**
97      * List the set of JBossObjects
98      *
99      * @param buffer the buffer
100     * @param objects the collection of objects
101     */
102    public static void list(JBossStringBuilder buffer, Collection   objects)
103    {
104       if (objects == null)
105          return;
106 
107       buffer.append('[');
108       if (objects.isEmpty() == false)
109       {
110          for (Iterator   i = objects.iterator(); i.hasNext();)
111          {
112             Object   object = i.next();
113             if (object instanceof JBossObject)
114                ((JBossObject) object).toShortString(buffer);
115             else
116                buffer.append(object.toString());
117             if (i.hasNext())
118                buffer.append(", ");
119          }
120       }
121       buffer.append(']');
122    }
123 
124    /**
125     * Create a new object
126     */
127    public JBossObject()
128    {
129       log = Logger.getLogger(getClass());
130    }
131    
132    /**
133     * Create a new object using the specified Logger instace
134     * 
135     * @param log the Logger instance to use
136     */
137    public JBossObject(Logger log)
138    {
139       this.log = (log != null) ? log : Logger.getLogger(getClass());
140    }
141    
142    /**
143     * Override toString to cache the value
144     * 
145     * @return the String
146     */
147    public String   toString()
148    {
149       if (cacheToString() == false)
150          return toStringImplementation();
151 
152       String   result = null;
153       if (toString != null)
154          result = (String  ) toString.get();
155 
156       if (result == null)
157       {
158          result = toStringImplementation();
159          toString = new SoftReference  (result);
160       }
161       return result;
162    }
163    
164    /**
165     * Override hashCode to cache the value
166     * 
167     * @return the hashCode
168     */
169    public int hashCode()
170    {
171       if (hashCode == Integer.MIN_VALUE || cacheGetHashCode() == false)
172          hashCode = getHashCode();
173       return hashCode;
174    }
175    
176    public Object   clone()
177    {
178       try
179       {
180          return super.clone();
181       }
182       catch (CloneNotSupportedException   e)
183       {
184          throw new RuntimeException  (e);
185       }
186    }
187 
188    public String   toShortString()
189    {
190       JBossStringBuilder buffer = new JBossStringBuilder();
191       toShortString(buffer);
192       return buffer.toString();
193    }
194    
195    /**
196     * Append the key class properties to the buffer
197     * 
198     * @param buffer the buffer
199     */
200    public void toShortString(JBossStringBuilder buffer)
201    {
202    }
203    
204    /**
205     * Get the class short name
206     * 
207     * @return the short name of the class
208     */
209    public String   getClassShortName()
210    {
211       String   longName = getClass().getName();
212       int dot = longName.lastIndexOf('.');
213       if (dot != -1)
214          return longName.substring(dot + 1);
215       return longName;
216    }
217 
218    /**
219     * Implementation of String
220     * 
221     * @return the string
222     */
223    protected String   toStringImplementation()
224    {
225       JBossStringBuilder buffer = new JBossStringBuilder();
226       buffer.append(getClassShortName()).append('@');
227       buffer.append(Integer.toHexString(System.identityHashCode(this)));
228       buffer.append('{');
229       toString(buffer);
230       buffer.append('}');
231       return buffer.toString();
232    }
233    
234    /**
235     * Flush the JBossObject cached values
236     */
237    protected void flushJBossObjectCache()
238    {
239       toString = null;
240       hashCode = Integer.MIN_VALUE;
241    }
242    
243    /**
244     * Append the class properties to the buffer
245     * 
246     * @param buffer the buffer
247     */
248    protected void toString(JBossStringBuilder buffer)
249    {
250    }
251    
252    /**
253     * Calculate the hashcode
254     * 
255     * @return the hash code
256     */
257    protected int getHashCode()
258    {
259       return super.hashCode();
260    }
261    
262    /**
263     * Whether we should cache the result toString()
264     * 
265     * @return true by default
266     */
267    protected boolean cacheToString()
268    {
269       return true;
270    }
271    
272    /**
273     * Whether we should cache the result hashCode()
274     * 
275     * @return true by default
276     */
277    protected boolean cacheGetHashCode()
278    {
279       return true;
280    }
281 }
282
A to Z: JavaDoc & Examples Daily Java News & Articles Open Source Projects Open Source Codes Free Computer Books Remove Frame
Popular Tags