InfoDescriptor


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50  
51  package org.apache.avalon.meta.info;
52  
53  import java.util.Properties  ;
54  
55  import org.apache.avalon.framework.Version;
56  
57  /**
58   * This class is used to provide explicit information to assembler
59   * and administrator about the Component. It includes information
60   * such as;
61   *
62   * <ul>
63   *   <li>a symbolic name</li>
64   *   <li>classname</li>
65   *   <li>version</li>
66   * </ul>
67   *
68   * <p>The InfoDescriptor also includes an arbitrary set
69   * of attributes about component. Usually these are container
70   * specific attributes that can store arbitrary information.
71   * The attributes should be stored with keys based on package
72   * name of container.
73   *
74   * @author <a HREF="mailto:dev@avalon.apache.org">Avalon Development Team</a>
75   * @version $Revision: 1.7 $ $Date: 2003/07/24 12:12:00 $
76   */
77  public final class InfoDescriptor extends Descriptor
78  {
79      //-------------------------------------------------------------------
80      // static
81      //-------------------------------------------------------------------
82  
83      public static final String   TRANSIENT = "transient";
84  
85      public static final String   SINGLETON = "singleton";
86  
87      public static final String   THREAD = "thread";
88  
89      public static final String   POOLED = "pooled";
90  
91      //-------------------------------------------------------------------
92      // immutable state
93      //-------------------------------------------------------------------
94  
95      /**
96       * The short name of the Component Type. Useful for displaying
97       * human readable strings describing the type in
98       * assembly tools or generators.
99       */
100     private final String   m_name;
101 
102     /**
103      * The implementation classname.
104      */
105     private final String   m_classname;
106 
107     /**
108      * The version of component that descriptor describes.
109      */
110     private final Version m_version;
111 
112     /**
113      * The component lifestyle.
114      */
115     private final String   m_lifestyle;
116 
117     /**
118      * The component configuration schema.
119      */
120     private final String   m_schema;
121 
122     //-------------------------------------------------------------------
123     // constructor
124     //-------------------------------------------------------------------
125 
126     /**
127      * Creation of a new component descriptor using a supplied name, key, version
128      * and attribute set.
129      *
130      * @param classname the implemetation classname
131      * @exception IllegalArgumentException if the implementation key is not a classname
132      */
133     public InfoDescriptor( final String   classname )
134             throws IllegalArgumentException  
135     {
136         this( null, classname, null, null, null, null );
137     }
138 
139     /**
140      * Creation of a new info descriptor using a supplied name, key, version
141      * and attribute set.
142      *
143      * @param name the component name
144      * @param classname the implemetation classname
145      * @param version the implementation version
146      * @param attributes a set of attributes associated with the component type
147      * @exception IllegalArgumentException if the implementation key is not a classname
148      */
149     public InfoDescriptor( final String   name,
150                            final String   classname,
151                            final Version version,
152                            final String   lifestyle,
153                            final String   schema,
154                            final Properties   attributes )
155             throws IllegalArgumentException  
156     {
157         super( attributes );
158 
159         if ( null == classname ) throw new NullPointerException  ( "classname" );
160 
161         if ( classname.indexOf( "/" ) > -1 )
162         {
163             throw new IllegalArgumentException  ( "classname: " + classname );
164         }
165 
166         m_classname = classname;
167         m_version = version;
168         m_schema = schema;
169 
170         if ( lifestyle == null )
171         {
172             m_lifestyle = TRANSIENT;
173         }
174         else
175         {
176             validateLifestyle( lifestyle );
177             m_lifestyle = lifestyle;
178         }
179 
180         if ( name != null )
181         {
182             m_name = name;
183         }
184         else
185         {
186             m_name = getClassName( classname );
187         }
188     }
189 
190     private void validateLifestyle( String   lifestyle ) throws IllegalArgumentException  
191     {
192         if ( lifestyle.equals( TRANSIENT )
193                 || lifestyle.equals( SINGLETON )
194                 || lifestyle.equals( THREAD )
195                 || lifestyle.equals( POOLED ) )
196         {
197             return;
198         }
199         final String   error = "Lifestyle policy not recognized: " + lifestyle;
200         throw new IllegalArgumentException  ( error );
201     }
202 
203     private String   getClassName( String   classname )
204     {
205         int i = classname.lastIndexOf( "." );
206         if ( i == -1 )
207         {
208             return classname.toLowerCase();
209         }
210         else
211         {
212             return classname.substring( i + 1, classname.length() ).toLowerCase();
213         }
214     }
215 
216     /**
217      * Return the symbolic name of component.
218      *
219      * @return the symbolic name of component.
220      */
221     public String   getName()
222     {
223         return m_name;
224     }
225 
226     /**
227      * Return the configuration schema.
228      *
229      * @return the schema declaration (possibly null)
230      */
231     public String   getConfigurationSchema()
232     {
233         return m_schema;
234     }
235 
236     /**
237      * Return the implementation class name for the component type.
238      *
239      * @return the implementation class name
240      */
241     public String   getClassname()
242     {
243         return m_classname;
244     }
245 
246     /**
247      * Return the version of component.
248      *
249      * @return the version of component.
250      */
251     public Version getVersion()
252     {
253         return m_version;
254     }
255 
256     /**
257      * Return the component lifestyle.
258      *
259      * @return the lifestyle
260      */
261     public String   getLifestyle()
262     {
263         return m_lifestyle;
264     }
265 
266     /**
267      * Return a string representation of the info descriptor.
268      * @return the stringified type
269      */
270     public String   toString()
271     {
272         return "[" + getName() + "] " + getClassname() + ":" + getVersion();
273     }
274 
275    /**
276     * Test is the supplied object is equal to this object.
277     * @return true if the object are equivalent
278     */
279     public boolean equals(Object   other)
280     {
281         boolean isEqual = super.equals(other) && other instanceof InfoDescriptor;
282 
283         if (isEqual)
284         {
285             InfoDescriptor info = (InfoDescriptor)other;
286             isEqual = isEqual && m_classname.equals( info.m_classname );
287             isEqual = isEqual && m_name.equals( info.m_name );
288             isEqual = isEqual && m_lifestyle.equals( info.m_lifestyle );
289 
290             if ( null == m_version )
291             {
292                 isEqual = isEqual && null == info.m_version;
293             }
294             else
295             {
296                 isEqual = isEqual && m_version.equals(info.m_version);
297             }
298         }
299 
300         return isEqual;
301     }
302 
303    /**
304     * Return the hashcode for the object.
305     * @return the hashcode value
306     */
307     public int hashCode()
308     {
309         int hash = super.hashCode();
310 
311         hash >>>= 7;
312         hash ^= m_classname.hashCode();
313         hash >>>= 7;
314 
315         if ( null != m_name )
316         {
317             hash >>>= 7;
318             hash ^= m_name.hashCode();
319         }
320 
321         if ( null != m_lifestyle )
322         {
323             hash >>>= 7;
324             hash ^= m_lifestyle.hashCode();
325         }
326 
327         if ( null != m_version )
328         {
329             hash >>>= 7;
330             hash ^= m_version.hashCode();
331         }
332 
333         return hash;
334     }
335 }
336
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