1 /*
2 * Copyright 1999-2004 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Sun designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Sun in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any questions.
24 */
25
26 package javax.naming;
27
28 import java.util.Vector;
29 import java.util.Enumeration;
30
31 /**
32 * This class represents a reference to an object that is found outside of
33 * the naming/directory system.
34 *<p>
35 * Reference provides a way of recording address information about
36 * objects which themselves are not directly bound to the naming/directory system.
37 *<p>
38 * A Reference consists of an ordered list of addresses and class information
39 * about the object being referenced.
40 * Each address in the list identifies a communications endpoint
41 * for the same conceptual object. The "communications endpoint"
42 * is information that indicates how to contact the object. It could
43 * be, for example, a network address, a location in memory on the
44 * local machine, another process on the same machine, etc.
45 * The order of the addresses in the list may be of significance
46 * to object factories that interpret the reference.
47 *<p>
48 * Multiple addresses may arise for
49 * various reasons, such as replication or the object offering interfaces
50 * over more than one communication mechanism. The addresses are indexed
51 * starting with zero.
52 *<p>
53 * A Reference also contains information to assist in creating an instance
54 * of the object to which this Reference refers. It contains the class name
55 * of that object, and the class name and location of the factory to be used
56 * to create the object.
57 * The class factory location is a space-separated list of URLs representing
58 * the class path used to load the factory. When the factory class (or
59 * any class or resource upon which it depends) needs to be loaded,
60 * each URL is used (in order) to attempt to load the class.
61 *<p>
62 * A Reference instance is not synchronized against concurrent access by multiple
63 * threads. Threads that need to access a single Reference concurrently should
64 * synchronize amongst themselves and provide the necessary locking.
65 *
66 * @author Rosanna Lee
67 * @author Scott Seligman
68 *
69 * @see RefAddr
70 * @see StringRefAddr
71 * @see BinaryRefAddr
72 * @since 1.3
73 */
74
75 /*<p>
76 * The serialized form of a Reference object consists of the class
77 * name of the object being referenced (a String), a Vector of the
78 * addresses (each a RefAddr), the name of the class factory (a
79 * String), and the location of the class factory (a String).
80 */
81
82
83 public class Reference implements Cloneable, java.io.Serializable {
84 /**
85 * Contains the fully-qualified name of the class of the object to which
86 * this Reference refers.
87 * @serial
88 * @see java.lang.Class#getName
89 */
90 protected String className;
91 /**
92 * Contains the addresses contained in this Reference.
93 * Initialized by constructor.
94 * @serial
95 */
96 protected Vector<RefAddr> addrs = null;
97
98 /**
99 * Contains the name of the factory class for creating
100 * an instance of the object to which this Reference refers.
101 * Initialized to null.
102 * @serial
103 */
104 protected String classFactory = null;
105
106 /**
107 * Contains the location of the factory class.
108 * Initialized to null.
109 * @serial
110 */
111 protected String classFactoryLocation = null;
112
113 /**
114 * Constructs a new reference for an object with class name 'className'.
115 * Class factory and class factory location are set to null.
116 * The newly created reference contains zero addresses.
117 *
118 * @param className The non-null class name of the object to which
119 * this reference refers.
120 */
121 public Reference(String className) {
122 this.className = className;
123 addrs = new Vector();
124 }
125
126 /**
127 * Constructs a new reference for an object with class name 'className' and
128 * an address.
129 * Class factory and class factory location are set to null.
130 *
131 * @param className The non-null class name of the object to
132 * which this reference refers.
133 * @param addr The non-null address of the object.
134 */
135 public Reference(String className, RefAddr addr) {
136 this.className = className;
137 addrs = new Vector();
138 addrs.addElement(addr);
139 }
140
141 /**
142 * Constructs a new reference for an object with class name 'className',
143 * and the class name and location of the object's factory.
144 *
145 * @param className The non-null class name of the object to which
146 * this reference refers.
147 * @param factory The possibly null class name of the object's factory.
148 * @param factoryLocation
149 * The possibly null location from which to load
150 * the factory (e.g. URL)
151 * @see javax.naming.spi.ObjectFactory
152 * @see javax.naming.spi.NamingManager#getObjectInstance
153 */
154 public Reference(String className, String factory, String factoryLocation) {
155 this(className);
156 classFactory = factory;
157 classFactoryLocation = factoryLocation;
158 }
159
160 /**
161 * Constructs a new reference for an object with class name 'className',
162 * the class name and location of the object's factory, and the address for
163 * the object.
164 *
165 * @param className The non-null class name of the object to
166 * which this reference refers.
167 * @param factory The possibly null class name of the object's factory.
168 * @param factoryLocation The possibly null location from which
169 * to load the factory (e.g. URL)
170 * @param addr The non-null address of the object.
171 * @see javax.naming.spi.ObjectFactory
172 * @see javax.naming.spi.NamingManager#getObjectInstance
173 */
174 public Reference(String className, RefAddr addr,
175 String factory, String factoryLocation) {
176 this(className, addr);
177 classFactory = factory;
178 classFactoryLocation = factoryLocation;
179 }
180
181 /**
182 * Retrieves the class name of the object to which this reference refers.
183 *
184 * @return The non-null fully-qualified class name of the object.
185 * (e.g. "java.lang.String")
186 */
187 public String getClassName() {
188 return className;
189 }
190
191 /**
192 * Retrieves the class name of the factory of the object
193 * to which this reference refers.
194 *
195 * @return The possibly null fully-qualified class name of the factory.
196 * (e.g. "java.lang.String")
197 */
198 public String getFactoryClassName() {
199 return classFactory;
200 }
201
202 /**
203 * Retrieves the location of the factory of the object
204 * to which this reference refers.
205 * If it is a codebase, then it is an ordered list of URLs,
206 * separated by spaces, listing locations from where the factory
207 * class definition should be loaded.
208 *
209 * @return The possibly null string containing the
210 * location for loading in the factory's class.
211 */
212 public String getFactoryClassLocation() {
213 return classFactoryLocation;
214 }
215
216 /**
217 * Retrieves the first address that has the address type 'addrType'.
218 * String.compareTo() is used to test the equality of the address types.
219 *
220 * @param addrType The non-null address type for which to find the address.
221 * @return The address in this reference with address type 'addrType;
222 * null if no such address exist.
223 */
224 public RefAddr get(String addrType) {
225 int len = addrs.size();
226 RefAddr addr;
227 for (int i = 0; i < len; i++) {
228 addr = (RefAddr) addrs.elementAt(i);
229 if (addr.getType().compareTo(addrType) == 0)
230 return addr;
231 }
232 return null;
233 }
234
235 /**
236 * Retrieves the address at index posn.
237 * @param posn The index of the address to retrieve.
238 * @return The address at the 0-based index posn. It must be in the
239 * range [0,getAddressCount()).
240 * @exception ArrayIndexOutOfBoundsException If posn not in the specified
241 * range.
242 */
243 public RefAddr get(int posn) {
244 return ((RefAddr) addrs.elementAt(posn));
245 }
246
247 /**
248 * Retrieves an enumeration of the addresses in this reference.
249 * When addresses are added, changed or removed from this reference,
250 * its effects on this enumeration are undefined.
251 *
252 * @return An non-null enumeration of the addresses
253 * (<tt>RefAddr</tt>) in this reference.
254 * If this reference has zero addresses, an enumeration with
255 * zero elements is returned.
256 */
257 public Enumeration<RefAddr> getAll() {
258 return addrs.elements();
259 }
260
261 /**
262 * Retrieves the number of addresses in this reference.
263 *
264 * @return The nonnegative number of addresses in this reference.
265 */
266 public int size() {
267 return addrs.size();
268 }
269
270 /**
271 * Adds an address to the end of the list of addresses.
272 *
273 * @param addr The non-null address to add.
274 */
275 public void add(RefAddr addr) {
276 addrs.addElement(addr);
277 }
278
279 /**
280 * Adds an address to the list of addresses at index posn.
281 * All addresses at index posn or greater are shifted up
282 * the list by one (away from index 0).
283 *
284 * @param posn The 0-based index of the list to insert addr.
285 * @param addr The non-null address to add.
286 * @exception ArrayIndexOutOfBoundsException If posn not in the specified
287 * range.
288 */
289 public void add(int posn, RefAddr addr) {
290 addrs.insertElementAt(addr, posn);
291 }
292
293 /**
294 * Deletes the address at index posn from the list of addresses.
295 * All addresses at index greater than posn are shifted down
296 * the list by one (towards index 0).
297 *
298 * @param posn The 0-based index of in address to delete.
299 * @return The address removed.
300 * @exception ArrayIndexOutOfBoundsException If posn not in the specified
301 * range.
302 */
303 public Object remove(int posn) {
304 Object r = addrs.elementAt(posn);
305 addrs.removeElementAt(posn);
306 return r;
307 }
308
309 /**
310 * Deletes all addresses from this reference.
311 */
312 public void clear() {
313 addrs.setSize(0);
314 }
315
316 /**
317 * Determines whether obj is a reference with the same addresses
318 * (in same order) as this reference.
319 * The addresses are checked using RefAddr.equals().
320 * In addition to having the same addresses, the Reference also needs to
321 * have the same class name as this reference.
322 * The class factory and class factory location are not checked.
323 * If obj is null or not an instance of Reference, null is returned.
324 *
325 * @param obj The possibly null object to check.
326 * @return true if obj is equal to this reference; false otherwise.
327 */
328 public boolean equals(Object obj) {
329 if ((obj != null) && (obj instanceof Reference)) {
330 Reference target = (Reference)obj;
331 // ignore factory information
332 if (target.className.equals(this.className) &&
333 target.size() == this.size()) {
334 Enumeration mycomps = getAll();
335 Enumeration comps = target.getAll();
336 while (mycomps.hasMoreElements())
337 if (!(mycomps.nextElement().equals(comps.nextElement())))
338 return false;
339 return true;
340 }
341 }
342 return false;
343 }
344
345 /**
346 * Computes the hash code of this reference.
347 * The hash code is the sum of the hash code of its addresses.
348 *
349 * @return A hash code of this reference as an int.
350 */
351 public int hashCode() {
352 int hash = className.hashCode();
353 for (Enumeration e = getAll(); e.hasMoreElements();)
354 hash += e.nextElement().hashCode();
355 return hash;
356 }
357
358 /**
359 * Generates the string representation of this reference.
360 * The string consists of the class name to which this reference refers,
361 * and the string representation of each of its addresses.
362 * This representation is intended for display only and not to be parsed.
363 *
364 * @return The non-null string representation of this reference.
365 */
366 public String toString() {
367 StringBuffer buf = new StringBuffer("Reference Class Name: " +
368 className + "\n");
369 int len = addrs.size();
370 for (int i = 0; i < len; i++)
371 buf.append(get(i).toString());
372
373 return buf.toString();
374 }
375
376 /**
377 * Makes a copy of this reference using its class name
378 * list of addresses, class factory name and class factory location.
379 * Changes to the newly created copy does not affect this Reference
380 * and vice versa.
381 */
382 public Object clone() {
383 Reference r = new Reference(className, classFactory, classFactoryLocation);
384 Enumeration<RefAddr> a = getAll();
385 r.addrs = new Vector();
386
387 while (a.hasMoreElements())
388 r.addrs.addElement(a.nextElement());
389 return r;
390 }
391 /**
392 * Use serialVersionUID from JNDI 1.1.1 for interoperability
393 */
394 private static final long serialVersionUID = -1673475790065791735L;
395 };
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