1 /*
2 * Copyright 2000-2007 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
27 package javax.management.openmbean;
28
29
30 // java import
31 //
32 import java.util.Arrays;
33
34 import javax.management.Descriptor;
35 import javax.management.MBeanConstructorInfo;
36 import javax.management.MBeanParameterInfo;
37
38
39 /**
40 * Describes a constructor of an Open MBean.
41 *
42 *
43 * @since 1.5
44 */
45 public class OpenMBeanConstructorInfoSupport
46 extends MBeanConstructorInfo
47 implements OpenMBeanConstructorInfo {
48
49 /* Serial version */
50 static final long serialVersionUID = -4400441579007477003L;
51
52
53 // As this instance is immutable,
54 // these two values need only be calculated once.
55 private transient Integer myHashCode = null;
56 private transient String myToString = null;
57
58 /**
59 * <p>Constructs an {@code OpenMBeanConstructorInfoSupport}
60 * instance, which describes the constructor of a class of open
61 * MBeans with the specified {@code name}, {@code description} and
62 * {@code signature}.</p>
63 *
64 * <p>The {@code signature} array parameter is internally copied,
65 * so that subsequent changes to the array referenced by {@code
66 * signature} have no effect on this instance.</p>
67 *
68 * @param name cannot be a null or empty string.
69 *
70 * @param description cannot be a null or empty string.
71 *
72 * @param signature can be null or empty if there are no
73 * parameters to describe.
74 *
75 * @throws IllegalArgumentException if {@code name} or {@code
76 * description} are null or empty string.
77 *
78 * @throws ArrayStoreException If {@code signature} is not an
79 * array of instances of a subclass of {@code MBeanParameterInfo}.
80 */
81 public OpenMBeanConstructorInfoSupport(String name,
82 String description,
83 OpenMBeanParameterInfo[] signature) {
84 this(name, description, signature, (Descriptor) null);
85 }
86
87 /**
88 * <p>Constructs an {@code OpenMBeanConstructorInfoSupport}
89 * instance, which describes the constructor of a class of open
90 * MBeans with the specified {@code name}, {@code description},
91 * {@code signature}, and {@code descriptor}.</p>
92 *
93 * <p>The {@code signature} array parameter is internally copied,
94 * so that subsequent changes to the array referenced by {@code
95 * signature} have no effect on this instance.</p>
96 *
97 * @param name cannot be a null or empty string.
98 *
99 * @param description cannot be a null or empty string.
100 *
101 * @param signature can be null or empty if there are no
102 * parameters to describe.
103 *
104 * @param descriptor The descriptor for the constructor. This may
105 * be null which is equivalent to an empty descriptor.
106 *
107 * @throws IllegalArgumentException if {@code name} or {@code
108 * description} are null or empty string.
109 *
110 * @throws ArrayStoreException If {@code signature} is not an
111 * array of instances of a subclass of {@code MBeanParameterInfo}.
112 *
113 * @since 1.6
114 */
115 public OpenMBeanConstructorInfoSupport(String name,
116 String description,
117 OpenMBeanParameterInfo[] signature,
118 Descriptor descriptor) {
119 super(name,
120 description,
121 arrayCopyCast(signature), // may throw an ArrayStoreException
122 descriptor);
123
124 // check parameters that should not be null or empty
125 // (unfortunately it is not done in superclass :-( ! )
126 //
127 if (name == null || name.trim().equals("")) {
128 throw new IllegalArgumentException("Argument name cannot be " +
129 "null or empty");
130 }
131 if (description == null || description.trim().equals("")) {
132 throw new IllegalArgumentException("Argument description cannot " +
133 "be null or empty");
134 }
135
136 }
137
138 private static MBeanParameterInfo[]
139 arrayCopyCast(OpenMBeanParameterInfo[] src) {
140 if (src == null)
141 return null;
142
143 MBeanParameterInfo[] dst = new MBeanParameterInfo[src.length];
144 System.arraycopy(src, 0, dst, 0, src.length);
145 // may throw an ArrayStoreException
146 return dst;
147 }
148
149
150 /* *** Commodity methods from java.lang.Object *** */
151
152
153 /**
154 * <p>Compares the specified {@code obj} parameter with this
155 * {@code OpenMBeanConstructorInfoSupport} instance for
156 * equality.</p>
157 *
158 * <p>Returns {@code true} if and only if all of the following
159 * statements are true:
160 *
161 * <ul>
162 * <li>{@code obj} is non null,</li>
163 * <li>{@code obj} also implements the {@code
164 * OpenMBeanConstructorInfo} interface,</li>
165 * <li>their names are equal</li>
166 * <li>their signatures are equal.</li>
167 * </ul>
168 *
169 * This ensures that this {@code equals} method works properly for
170 * {@code obj} parameters which are different implementations of
171 * the {@code OpenMBeanConstructorInfo} interface.
172 *
173 * @param obj the object to be compared for equality with this
174 * {@code OpenMBeanConstructorInfoSupport} instance;
175 *
176 * @return {@code true} if the specified object is equal to this
177 * {@code OpenMBeanConstructorInfoSupport} instance.
178 */
179 public boolean equals(Object obj) {
180
181 // if obj is null, return false
182 //
183 if (obj == null) {
184 return false;
185 }
186
187 // if obj is not a OpenMBeanConstructorInfo, return false
188 //
189 OpenMBeanConstructorInfo other;
190 try {
191 other = (OpenMBeanConstructorInfo) obj;
192 } catch (ClassCastException e) {
193 return false;
194 }
195
196 // Now, really test for equality between this
197 // OpenMBeanConstructorInfo implementation and the other:
198 //
199
200 // their Name should be equal
201 if ( ! this.getName().equals(other.getName()) ) {
202 return false;
203 }
204
205 // their Signatures should be equal
206 if ( ! Arrays.equals(this.getSignature(), other.getSignature()) ) {
207 return false;
208 }
209
210 // All tests for equality were successfull
211 //
212 return true;
213 }
214
215 /**
216 * <p>Returns the hash code value for this {@code
217 * OpenMBeanConstructorInfoSupport} instance.</p>
218 *
219 * <p>The hash code of an {@code OpenMBeanConstructorInfoSupport}
220 * instance is the sum of the hash codes of all elements of
221 * information used in {@code equals} comparisons (ie: its name
222 * and signature, where the signature hashCode is calculated by a
223 * call to {@code
224 * java.util.Arrays.asList(this.getSignature).hashCode()}).</p>
225 *
226 * <p>This ensures that {@code t1.equals(t2)} implies that {@code
227 * t1.hashCode()==t2.hashCode()} for any two {@code
228 * OpenMBeanConstructorInfoSupport} instances {@code t1} and
229 * {@code t2}, as required by the general contract of the method
230 * {@link Object#hashCode() Object.hashCode()}.</p>
231 *
232 * <p>However, note that another instance of a class implementing
233 * the {@code OpenMBeanConstructorInfo} interface may be equal to
234 * this {@code OpenMBeanConstructorInfoSupport} instance as
235 * defined by {@link #equals(java.lang.Object)}, but may have a
236 * different hash code if it is calculated differently.</p>
237 *
238 * <p>As {@code OpenMBeanConstructorInfoSupport} instances are
239 * immutable, the hash code for this instance is calculated once,
240 * on the first call to {@code hashCode}, and then the same value
241 * is returned for subsequent calls.</p>
242 *
243 * @return the hash code value for this {@code
244 * OpenMBeanConstructorInfoSupport} instance
245 */
246 public int hashCode() {
247
248 // Calculate the hash code value if it has not yet been done
249 // (ie 1st call to hashCode())
250 //
251 if (myHashCode == null) {
252 int value = 0;
253 value += this.getName().hashCode();
254 value += Arrays.asList(this.getSignature()).hashCode();
255 myHashCode = Integer.valueOf(value);
256 }
257
258 // return always the same hash code for this instance (immutable)
259 //
260 return myHashCode.intValue();
261 }
262
263 /**
264 * <p>Returns a string representation of this {@code
265 * OpenMBeanConstructorInfoSupport} instance.</p>
266 *
267 * <p>The string representation consists of the name of this class
268 * (ie {@code
269 * javax.management.openmbean.OpenMBeanConstructorInfoSupport}),
270 * the name and signature of the described constructor and the
271 * string representation of its descriptor.</p>
272 *
273 * <p>As {@code OpenMBeanConstructorInfoSupport} instances are
274 * immutable, the string representation for this instance is
275 * calculated once, on the first call to {@code toString}, and
276 * then the same value is returned for subsequent calls.</p>
277 *
278 * @return a string representation of this {@code
279 * OpenMBeanConstructorInfoSupport} instance
280 */
281 public String toString() {
282
283 // Calculate the string value if it has not yet been done (ie
284 // 1st call to toString())
285 //
286 if (myToString == null) {
287 myToString = new StringBuilder()
288 .append(this.getClass().getName())
289 .append("(name=")
290 .append(this.getName())
291 .append(",signature=")
292 .append(Arrays.asList(this.getSignature()).toString())
293 .append(",descriptor=")
294 .append(this.getDescriptor())
295 .append(")")
296 .toString();
297 }
298
299 // return always the same string representation for this
300 // instance (immutable)
301 //
302 return myToString;
303 }
304
305 }
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