1/* 2 * Copyright (c) 2000, 2017, Oracle and/or its affiliates. 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. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25/* 26 * @author IBM Corp. 27 * 28 * Copyright IBM Corp. 1999-2000. All rights reserved. 29 */ 30 31package javax.management; 32 33import java.io.Serializable; 34 35// Javadoc imports: 36import java.lang.management.MemoryUsage; 37import java.util.Arrays; 38import java.util.Locale; 39import java.util.ResourceBundle; 40import javax.management.openmbean.CompositeData; 41import javax.management.openmbean.OpenMBeanAttributeInfoSupport; 42import javax.management.openmbean.OpenMBeanOperationInfoSupport; 43import javax.management.openmbean.OpenMBeanParameterInfoSupport; 44import javax.management.openmbean.OpenType; 45 46/** 47 * <p>Additional metadata for a JMX element. A {@code Descriptor} 48 * is associated with a {@link MBeanInfo}, {@link MBeanAttributeInfo}, etc. 49 * It consists of a collection of fields. A field is a name and an 50 * associated value.</p> 51 * 52 * <p>Field names are not case-sensitive. The names {@code descriptorType}, 53 * {@code descriptortype}, and {@code DESCRIPTORTYPE} are all equivalent. 54 * However, the case that was used when the field was first set is preserved 55 * in the result of the {@link #getFields} and {@link #getFieldNames} 56 * methods.</p> 57 * 58 * <p>Not all field names and values are predefined. 59 * New fields can be defined and added by any program.</p> 60 * 61 * <p>A descriptor can be mutable or immutable. 62 * An immutable descriptor, once created, never changes. 63 * The <code>Descriptor</code> methods that could modify the contents 64 * of the descriptor will throw an exception 65 * for an immutable descriptor. Immutable descriptors are usually 66 * instances of {@link ImmutableDescriptor} or a subclass. Mutable 67 * descriptors are usually instances of 68 * {@link javax.management.modelmbean.DescriptorSupport} or a subclass. 69 * 70 * <p>Certain fields are used by the JMX implementation. This means 71 * either that the presence of the field may change the behavior of 72 * the JMX API or that the field may be set in descriptors returned by 73 * the JMX API. These fields appear in <i>italics</i> in the table 74 * below, and each one has a corresponding constant in the {@link JMX} 75 * class. For example, the field {@code defaultValue} is represented 76 * by the constant {@link JMX#DEFAULT_VALUE_FIELD}.</p> 77 * 78 * <p>Certain other fields have conventional meanings described in the 79 * table below but they are not required to be understood or set by 80 * the JMX implementation.</p> 81 * 82 * <p>Field names defined by the JMX specification in this and all 83 * future versions will never contain a period (.). Users can safely 84 * create their own fields by including a period in the name and be 85 * sure that these names will not collide with any future version of 86 * the JMX API. It is recommended to follow the Java package naming 87 * convention to avoid collisions between field names from different 88 * origins. For example, a field created by {@code example.com} might 89 * have the name {@code com.example.interestLevel}.</p> 90 * 91 * <p>Note that the values in the {@code defaultValue}, {@code 92 * legalValues}, {@code maxValue}, and {@code minValue} fields should 93 * be consistent with the type returned by the {@code getType()} 94 * method for the associated {@code MBeanAttributeInfo} or {@code 95 * MBeanParameterInfo}. For MXBeans, this means that they should be 96 * of the mapped Java type, called <em>opendata</em>(J) in the <a 97 * href="MXBean.html#mapping-rules">MXBean type mapping rules</a>.</p> 98 * 99 * <table class="striped"> 100 * <caption style="display:none">Descriptor Fields</caption> 101 * <thead> 102 * <tr><th scope="col">Name</th> 103 * <th scope="col">Type</th> 104 * <th scope="col">Used in</th> 105 * <th scope="col">Meaning</th></tr> 106 * </thead> 107 * 108 * <tbody style="text-align:left"> 109 * <tr id="defaultValue"><th scope="row"><i>defaultValue</i><td>Object</td> 110 * <td>MBeanAttributeInfo<br>MBeanParameterInfo</td> 111 * 112 * <td>Default value for an attribute or parameter. See 113 * {@link javax.management.openmbean}.</td> 114 * 115 * <tr><th scope="row">deprecated</th><td>String</td><td>Any</td> 116 * 117 * <td>An indication that this element of the information model is no 118 * longer recommended for use. A set of MBeans defined by an 119 * application is collectively called an <em>information model</em>. 120 * The convention is for the value of this field to contain a string 121 * that is the version of the model in which the element was first 122 * deprecated, followed by a space, followed by an explanation of the 123 * deprecation, for example {@code "1.3 Replaced by the Capacity 124 * attribute"}.</td> 125 * 126 * <tr><th scope="row" id="descriptionResourceBundleBaseName">descriptionResource<br> 127 * BundleBaseName</th><td>String</td><td>Any</td> 128 * 129 * <td>The base name for the {@link ResourceBundle} in which the key given in 130 * the {@code descriptionResourceKey} field can be found, for example 131 * {@code "com.example.myapp.MBeanResources"}. The meaning of this 132 * field is defined by this specification but the field is not set or 133 * used by the JMX API itself.</td> 134 * 135 * <tr><th scope="row" id="descriptionResourceKey">descriptionResourceKey</th> 136 * <td>String</td><td>Any</td> 137 * 138 * <td>A resource key for the description of this element. In 139 * conjunction with the {@code descriptionResourceBundleBaseName}, 140 * this can be used to find a localized version of the description. 141 * The meaning of this field is defined by this specification but the 142 * field is not set or used by the JMX API itself.</td> 143 * 144 * <tr><th scope="row">enabled</th><td>String</td> 145 * <td>MBeanAttributeInfo<br>MBeanNotificationInfo<br>MBeanOperationInfo</td> 146 * 147 * <td>The string {@code "true"} or {@code "false"} according as this 148 * item is enabled. When an attribute or operation is not enabled, it 149 * exists but cannot currently be accessed. A user interface might 150 * present it as a greyed-out item. For example, an attribute might 151 * only be meaningful after the {@code start()} method of an MBean has 152 * been called, and is otherwise disabled. Likewise, a notification 153 * might be disabled if it cannot currently be emitted but could be in 154 * other circumstances.</td> 155 * 156 * <tr id="exceptions"><th scope="row">exceptions<td>String[]</td> 157 * <td>MBeanAttributeInfo, MBeanConstructorInfo, MBeanOperationInfo</td> 158 * 159 * <td>The class names of the exceptions that can be thrown when invoking a 160 * constructor or operation, or getting an attribute. The meaning of this field 161 * is defined by this specification but the field is not set or used by the 162 * JMX API itself. Exceptions thrown when 163 * setting an attribute are specified by the field 164 * <a href="#setExceptions">{@code setExceptions}</a>. 165 * 166 * <tr id="immutableInfo"><th scope="row"><i>immutableInfo</i><td>String</td> 167 * <td>MBeanInfo</td> 168 * 169 * <td>The string {@code "true"} or {@code "false"} according as this 170 * MBean's MBeanInfo is <em>immutable</em>. When this field is true, 171 * the MBeanInfo for the given MBean is guaranteed not to change over 172 * the lifetime of the MBean. Hence, a client can read it once and 173 * cache the read value. When this field is false or absent, there is 174 * no such guarantee, although that does not mean that the MBeanInfo 175 * will necessarily change. See also the <a 176 * href="MBeanInfo.html#info-changed">{@code "jmx.mbean.info.changed"}</a> 177 * notification.</td> 178 * 179 * <tr id="infoTimeout"><th scope="row">infoTimeout</th><td>String<br>Long</td><td>MBeanInfo</td> 180 * 181 * <td>The time in milli-seconds that the MBeanInfo can reasonably be 182 * expected to be unchanged. The value can be a {@code Long} or a 183 * decimal string. This provides a hint from a DynamicMBean or any 184 * MBean that does not define {@code immutableInfo} as {@code true} 185 * that the MBeanInfo is not likely to change within this period and 186 * therefore can be cached. When this field is missing or has the 187 * value zero, it is not recommended to cache the MBeanInfo unless it 188 * has the {@code immutableInfo} set to {@code true} or it has <a 189 * href="MBeanInfo.html#info-changed">{@code "jmx.mbean.info.changed"}</a> in 190 * its {@link MBeanNotificationInfo} array.</td></tr> 191 * 192 * <tr id="interfaceClassName"><th scope="row"><i>interfaceClassName</i></th> 193 * <td>String</td><td>MBeanInfo</td> 194 * 195 * <td>The Java interface name for a Standard MBean or MXBean, as 196 * returned by {@link Class#getName()}. A Standard MBean or MXBean 197 * registered directly in the MBean Server or created using the {@link 198 * StandardMBean} class will have this field in its MBeanInfo 199 * Descriptor.</td> 200 * 201 * <tr id="legalValues"><th scope="row"><i>legalValues</i></th> 202 * <td>{@literal Set<?>}</td><td>MBeanAttributeInfo<br>MBeanParameterInfo</td> 203 * 204 * <td>Legal values for an attribute or parameter. See 205 * {@link javax.management.openmbean}.</td> 206 * 207 * <tr id="locale"><th scope="row">locale</th> 208 * <td>String</td><td>Any</td> 209 * 210 * <td>The {@linkplain Locale locale} of the description in this 211 * {@code MBeanInfo}, {@code MBeanAttributeInfo}, etc, as returned 212 * by {@link Locale#toString()}.</td> 213 * 214 * <tr id="maxValue"><th scope="row"><i>maxValue</i><td>Object</td> 215 * <td>MBeanAttributeInfo<br>MBeanParameterInfo</td> 216 * 217 * <td>Maximum legal value for an attribute or parameter. See 218 * {@link javax.management.openmbean}.</td> 219 * 220 * <tr id="metricType"><th scope="row">metricType</th><td>String</td> 221 * <td>MBeanAttributeInfo<br>MBeanOperationInfo</td> 222 * 223 * <td>The type of a metric, one of the strings "counter" or "gauge". 224 * A metric is a measurement exported by an MBean, usually an 225 * attribute but sometimes the result of an operation. A metric that 226 * is a <em>counter</em> has a value that never decreases except by 227 * being reset to a starting value. Counter metrics are almost always 228 * non-negative integers. An example might be the number of requests 229 * received. A metric that is a <em>gauge</em> has a numeric value 230 * that can increase or decrease. Examples might be the number of 231 * open connections or a cache hit rate or a temperature reading. 232 * 233 * <tr id="minValue"><th scope="row"><i>minValue</i><td>Object</td> 234 * <td>MBeanAttributeInfo<br>MBeanParameterInfo</td> 235 * 236 * <td>Minimum legal value for an attribute or parameter. See 237 * {@link javax.management.openmbean}.</td> 238 * 239 * <tr id="mxbean"><th scope="row"><i>mxbean</i><td>String</td> 240 * <td>MBeanInfo</td> 241 * 242 * <td>The string {@code "true"} or {@code "false"} according as this 243 * MBean is an {@link MXBean}. A Standard MBean or MXBean registered 244 * directly with the MBean Server or created using the {@link 245 * StandardMBean} class will have this field in its MBeanInfo 246 * Descriptor.</td> 247 * 248 * <tr id="openType"><th scope="row"><i>openType</i><td>{@link OpenType}</td> 249 * <td>MBeanAttributeInfo<br>MBeanOperationInfo<br>MBeanParameterInfo</td> 250 * 251 * <td><p>The Open Type of this element. In the case of {@code 252 * MBeanAttributeInfo} and {@code MBeanParameterInfo}, this is the 253 * Open Type of the attribute or parameter. In the case of {@code 254 * MBeanOperationInfo}, it is the Open Type of the return value. This 255 * field is set in the Descriptor for all instances of {@link 256 * OpenMBeanAttributeInfoSupport}, {@link 257 * OpenMBeanOperationInfoSupport}, and {@link 258 * OpenMBeanParameterInfoSupport}. It is also set for attributes, 259 * operations, and parameters of MXBeans.</p> 260 * 261 * <p>This field can be set for an {@code MBeanNotificationInfo}, in 262 * which case it indicates the Open Type that the {@link 263 * Notification#getUserData() user data} will have.</td> 264 * 265 * <tr id="originalType"><th scope="row"><i>originalType</i><td>String</td> 266 * <td>MBeanAttributeInfo<br>MBeanOperationInfo<br>MBeanParameterInfo</td> 267 * 268 * <td><p>The original Java type of this element as it appeared in the 269 * {@link MXBean} interface method that produced this {@code 270 * MBeanAttributeInfo} (etc). For example, a method<br> <code>public 271 * </code> {@link MemoryUsage}<code> getHeapMemoryUsage();</code><br> 272 * in an MXBean interface defines an attribute called {@code 273 * HeapMemoryUsage} of type {@link CompositeData}. The {@code 274 * originalType} field in the Descriptor for this attribute will have 275 * the value {@code "java.lang.management.MemoryUsage"}. 276 * 277 * <p>The format of this string is described in the section <a 278 * href="MXBean.html#type-names">Type Names</a> of the MXBean 279 * specification.</p> 280 * 281 * <tr id="setExceptions"><th scope="row"><i>setExceptions</i><td>String[]</td> 282 * <td>MBeanAttributeInfo</td> 283 * 284 * <td>The class names of the exceptions that can be thrown when setting 285 * an attribute. The meaning of this field 286 * is defined by this specification but the field is not set or used by the 287 * JMX API itself. Exceptions thrown when getting an attribute are specified 288 * by the field <a href="#exceptions">{@code exceptions}</a>. 289 * 290 * <tr><th scope="row">severity</th><td>String<br>Integer</td> 291 * <td>MBeanNotificationInfo</td> 292 * 293 * <td>The severity of this notification. It can be 0 to mean 294 * unknown severity or a value from 1 to 6 representing decreasing 295 * levels of severity. It can be represented as a decimal string or 296 * an {@code Integer}.</td> 297 * 298 * <tr><th scope="row">since</th><td>String</td><td>Any</td> 299 * 300 * <td>The version of the information model in which this element 301 * was introduced. A set of MBeans defined by an application is 302 * collectively called an <em>information model</em>. The 303 * application may also define versions of this model, and use the 304 * {@code "since"} field to record the version in which an element 305 * first appeared.</td> 306 * 307 * <tr><th scope="row">units</th><td>String</td> 308 * <td>MBeanAttributeInfo<br>MBeanParameterInfo<br>MBeanOperationInfo</td> 309 * 310 * <td>The units in which an attribute, parameter, or operation return 311 * value is measured, for example {@code "bytes"} or {@code 312 * "seconds"}.</td> 313 * 314 * </tbody> 315 * </table> 316 * 317 * <p>Some additional fields are defined by Model MBeans. See the 318 * information for <a href="modelmbean/ModelMBeanInfo.html#descriptor"><!-- 319 * -->{@code ModelMBeanInfo}</a>, 320 * <a href="modelmbean/ModelMBeanAttributeInfo.html#descriptor"><!-- 321 * -->{@code ModelMBeanAttributeInfo}</a>, 322 * <a href="modelmbean/ModelMBeanConstructorInfo.html#descriptor"><!-- 323 * -->{@code ModelMBeanConstructorInfo}</a>, 324 * <a href="modelmbean/ModelMBeanNotificationInfo.html#descriptor"><!-- 325 * -->{@code ModelMBeanNotificationInfo}</a>, and 326 * <a href="modelmbean/ModelMBeanOperationInfo.html#descriptor"><!-- 327 * -->{@code ModelMBeanOperationInfo}</a>, as 328 * well as the chapter "Model MBeans" of the <a 329 * href="http://www.oracle.com/technetwork/java/javase/tech/javamanagement-140525.html">JMX 330 * Specification</a>. The following table summarizes these fields. Note 331 * that when the Type in this table is Number, a String that is the decimal 332 * representation of a Long can also be used.</p> 333 * 334 * <p>Nothing prevents the use of these fields in MBeans that are not Model 335 * MBeans. The <a href="#displayName">displayName</a>, <a href="#severity"><!-- 336 * -->severity</a>, and <a href="#visibility">visibility</a> fields are of 337 * interest outside Model MBeans, for example. But only Model MBeans have 338 * a predefined behavior for these fields.</p> 339 * 340 * <table class="striped"> 341 * <caption style="display:none">ModelMBean Fields</caption> 342 * 343 * <thead> 344 * <tr><th scope="col">Name</th> 345 * <th scope="col">Type</th> 346 * <th scope="col">Used in</th> 347 * <th scope="col">Meaning</th></tr> 348 * </thead> 349 * 350 * <tbody style="text-align:left"> 351 * <tr><th scope="row">class</th><td>String</td><td>ModelMBeanOperationInfo</td> 352 * <td>Class where method is defined (fully qualified).</td></tr> 353 * 354 * <tr><th scope="row">currencyTimeLimit</th><td>Number</td> 355 * <td>ModelMBeanInfo<br>ModelMBeanAttributeInfo<br>ModelMBeanOperationInfo</td> 356 * <td>How long cached value is valid: <0 never, =0 always, 357 * >0 seconds.</td></tr> 358 * 359 * <tr><th scope="row">default</th><td>Object</td><td>ModelMBeanAttributeInfo</td> 360 * <td>Default value for attribute.</td></tr> 361 * 362 * <tr><th scope="row">descriptorType</th><td>String</td><td>Any</td> 363 * <td>Type of descriptor, "mbean", "attribute", "constructor", "operation", 364 * or "notification".</td></tr> 365 * 366 * <tr id="displayName"><th scope="row">displayName</th><td>String</td><td>Any</td> 367 * <td>Human readable name of this item.</td></tr> 368 * 369 * <tr><th scope="row">export</th><td>String</td><td>ModelMBeanInfo</td> 370 * <td>Name to be used to export/expose this MBean so that it is 371 * findable by other JMX Agents.</td></tr> 372 * 373 * <tr><th scope="row">getMethod</th><td>String</td><td>ModelMBeanAttributeInfo</td> 374 * <td>Name of operation descriptor for get method.</td></tr> 375 * 376 * <tr><th scope="row">lastUpdatedTimeStamp</th><td>Number</td> 377 * <td>ModelMBeanAttributeInfo<br>ModelMBeanOperationInfo</td> 378 * <td>When <a href="#value-field">value</a> was set.</td></tr> 379 * 380 * <tr><th scope="row">log</th><td>String</td><td>ModelMBeanInfo<br>ModelMBeanNotificationInfo</td> 381 * <td>t or T: log all notifications, f or F: log no notifications.</td></tr> 382 * 383 * <tr><th scope="row">logFile</th><td>String</td><td>ModelMBeanInfo<br>ModelMBeanNotificationInfo</td> 384 * <td>Fully qualified filename to log events to.</td></tr> 385 * 386 * <tr><th scope="row">messageID</th><td>String</td><td>ModelMBeanNotificationInfo</td> 387 * <td>Unique key for message text (to allow translation, analysis).</td></tr> 388 * 389 * <tr><th scope="row">messageText</th><td>String</td><td>ModelMBeanNotificationInfo</td> 390 * <td>Text of notification.</td></tr> 391 * 392 * <tr><th scope="row">name</th><td>String</td><td>Any</td> 393 * <td>Name of this item.</td></tr> 394 * 395 * <tr><th scope="row">persistFile</th><td>String</td><td>ModelMBeanInfo</td> 396 * <td>File name into which the MBean should be persisted.</td></tr> 397 * 398 * <tr><th scope="row">persistLocation</th><td>String</td><td>ModelMBeanInfo</td> 399 * <td>The fully qualified directory name where the MBean should be 400 * persisted (if appropriate).</td></tr> 401 * 402 * <tr><th scope="row">persistPeriod</th><td>Number</td> 403 * <td>ModelMBeanInfo<br>ModelMBeanAttributeInfo</td> 404 * <td>Frequency of persist cycle in seconds. Used when persistPolicy is 405 * "OnTimer" or "NoMoreOftenThan".</td></tr> 406 * 407 * <tr><th scope="row">persistPolicy</th><td>String</td> 408 * <td>ModelMBeanInfo<br>ModelMBeanAttributeInfo</td> 409 * <td>One of: OnUpdate|OnTimer|NoMoreOftenThan|OnUnregister|Always|Never. 410 * See the section "MBean Descriptor Fields" in the JMX specification 411 * document.</td></tr> 412 * 413 * <tr><th scope="row">presentationString</th><td>String</td><td>Any</td> 414 * <td>XML formatted string to allow presentation of data.</td></tr> 415 * 416 * <tr><th scope="row">protocolMap</th><td>Descriptor</td><td>ModelMBeanAttributeInfo</td> 417 * <td>See the section "Protocol Map Support" in the JMX specification 418 * document. Mappings must be appropriate for the attribute and entries 419 * can be updated or augmented at runtime.</td></tr> 420 * 421 * <tr><th scope="row">role</th><td>String</td> 422 * <td>ModelMBeanConstructorInfo<br>ModelMBeanOperationInfo</td> 423 * <td>One of "constructor", "operation", "getter", or "setter".</td></tr> 424 * 425 * <tr><th scope="row">setMethod</th><td>String</td><td>ModelMBeanAttributeInfo</td> 426 * <td>Name of operation descriptor for set method.</td></tr> 427 * 428 * <tr id="severity"><th scope="row">severity</th><td>Number</td> 429 * <td>ModelMBeanNotificationInfo</td> 430 * <td>0-6 where 0: unknown; 1: non-recoverable; 431 * 2: critical, failure; 3: major, severe; 432 * 4: minor, marginal, error; 5: warning; 433 * 6: normal, cleared, informative</td></tr> 434 * 435 * <tr><th scope="row">targetObject</th><td>Object</td><td>ModelMBeanOperationInfo</td> 436 * <td>Object on which to execute this method.</td></tr> 437 * 438 * <tr><th scope="row">targetType</th><td>String</td><td>ModelMBeanOperationInfo</td> 439 * <td>type of object reference for targetObject. Can be: 440 * ObjectReference | Handle | EJBHandle | IOR | RMIReference.</td></tr> 441 * 442 * <tr id="value-field"><th scope="row">value</th><td>Object</td> 443 * <td>ModelMBeanAttributeInfo<br>ModelMBeanOperationInfo</td> 444 * <td>Current (cached) value for attribute or operation.</td></tr> 445 * 446 * <tr id="visibility"><th scope="row">visibility</th><td>Number</td><td>Any</td> 447 * <td>1-4 where 1: always visible, 4: rarely visible.</td></tr> 448 * 449 * </tbody> 450 * </table> 451 * 452 * @since 1.5 453 */ 454public interface Descriptor extends Serializable, Cloneable 455{ 456 457 /** 458 * Returns the value for a specific field name, or null if no value 459 * is present for that name. 460 * 461 * @param fieldName the field name. 462 * 463 * @return the corresponding value, or null if the field is not present. 464 * 465 * @exception RuntimeOperationsException if the field name is illegal. 466 */ 467 public Object getFieldValue(String fieldName) 468 throws RuntimeOperationsException; 469 470 /** 471 * <p>Sets the value for a specific field name. This will 472 * modify an existing field or add a new field.</p> 473 * 474 * <p>The field value will be validated before it is set. 475 * If it is not valid, then an exception will be thrown. 476 * The meaning of validity is dependent on the descriptor 477 * implementation.</p> 478 * 479 * @param fieldName The field name to be set. Cannot be null or empty. 480 * @param fieldValue The field value to be set for the field 481 * name. Can be null if that is a valid value for the field. 482 * 483 * @exception RuntimeOperationsException if the field name or field value 484 * is illegal (wrapped exception is {@link IllegalArgumentException}); or 485 * if the descriptor is immutable (wrapped exception is 486 * {@link UnsupportedOperationException}). 487 */ 488 public void setField(String fieldName, Object fieldValue) 489 throws RuntimeOperationsException; 490 491 492 /** 493 * Returns all of the fields contained in this descriptor as a string array. 494 * 495 * @return String array of fields in the format <i>fieldName=fieldValue</i> 496 * <br>If the value of a field is not a String, then the toString() method 497 * will be called on it and the returned value, enclosed in parentheses, 498 * used as the value for the field in the returned array. If the value 499 * of a field is null, then the value of the field in the returned array 500 * will be empty. If the descriptor is empty, you will get 501 * an empty array. 502 * 503 * @see #setFields 504 */ 505 public String[] getFields(); 506 507 508 /** 509 * Returns all the field names in the descriptor. 510 * 511 * @return String array of field names. If the descriptor is empty, 512 * you will get an empty array. 513 */ 514 public String[] getFieldNames(); 515 516 /** 517 * Returns all the field values in the descriptor as an array of Objects. The 518 * returned values are in the same order as the {@code fieldNames} String array parameter. 519 * 520 * @param fieldNames String array of the names of the fields that 521 * the values should be returned for. If the array is empty then 522 * an empty array will be returned. If the array is null then all 523 * values will be returned, as if the parameter were the array 524 * returned by {@link #getFieldNames()}. If a field name in the 525 * array does not exist, including the case where it is null or 526 * the empty string, then null is returned for the matching array 527 * element being returned. 528 * 529 * @return Object array of field values. If the list of {@code fieldNames} 530 * is empty, you will get an empty array. 531 */ 532 public Object[] getFieldValues(String... fieldNames); 533 534 /** 535 * Removes a field from the descriptor. 536 * 537 * @param fieldName String name of the field to be removed. 538 * If the field name is illegal or the field is not found, 539 * no exception is thrown. 540 * 541 * @exception RuntimeOperationsException if a field of the given name 542 * exists and the descriptor is immutable. The wrapped exception will 543 * be an {@link UnsupportedOperationException}. 544 */ 545 public void removeField(String fieldName); 546 547 /** 548 * <p>Sets all fields in the field names array to the new value with 549 * the same index in the field values array. Array sizes must match.</p> 550 * 551 * <p>The field value will be validated before it is set. 552 * If it is not valid, then an exception will be thrown. 553 * If the arrays are empty, then no change will take effect.</p> 554 * 555 * @param fieldNames String array of field names. The array and array 556 * elements cannot be null. 557 * @param fieldValues Object array of the corresponding field values. 558 * The array cannot be null. Elements of the array can be null. 559 * 560 * @throws RuntimeOperationsException if the change fails for any reason. 561 * Wrapped exception is {@link IllegalArgumentException} if 562 * {@code fieldNames} or {@code fieldValues} is null, or if 563 * the arrays are of different lengths, or if there is an 564 * illegal value in one of them. 565 * Wrapped exception is {@link UnsupportedOperationException} 566 * if the descriptor is immutable, and the call would change 567 * its contents. 568 * 569 * @see #getFields 570 */ 571 public void setFields(String[] fieldNames, Object[] fieldValues) 572 throws RuntimeOperationsException; 573 574 575 /** 576 * <p>Returns a descriptor which is equal to this descriptor. 577 * Changes to the returned descriptor will have no effect on this 578 * descriptor, and vice versa. If this descriptor is immutable, 579 * it may fulfill this condition by returning itself.</p> 580 * @exception RuntimeOperationsException for illegal value for field names 581 * or field values. 582 * If the descriptor construction fails for any reason, this exception will 583 * be thrown. 584 * @return A descriptor which is equal to this descriptor. 585 */ 586 public Object clone() throws RuntimeOperationsException; 587 588 589 /** 590 * Returns true if all of the fields have legal values given their 591 * names. 592 * 593 * @return true if the values are legal. 594 * 595 * @exception RuntimeOperationsException If the validity checking fails for 596 * any reason, this exception will be thrown. 597 * The method returns false if the descriptor is not valid, but throws 598 * this exception if the attempt to determine validity fails. 599 */ 600 public boolean isValid() throws RuntimeOperationsException; 601 602 /** 603 * <p>Compares this descriptor to the given object. The objects are equal if 604 * the given object is also a Descriptor, and if the two Descriptors have 605 * the same field names (possibly differing in case) and the same 606 * associated values. The respective values for a field in the two 607 * Descriptors are equal if the following conditions hold:</p> 608 * 609 * <ul> 610 * <li>If one value is null then the other must be too.</li> 611 * <li>If one value is a primitive array then the other must be a primitive 612 * array of the same type with the same elements.</li> 613 * <li>If one value is an object array then the other must be too and 614 * {@link Arrays#deepEquals(Object[],Object[])} must return true.</li> 615 * <li>Otherwise {@link Object#equals(Object)} must return true.</li> 616 * </ul> 617 * 618 * @param obj the object to compare with. 619 * 620 * @return {@code true} if the objects are the same; {@code false} 621 * otherwise. 622 * 623 * @since 1.6 624 */ 625 public boolean equals(Object obj); 626 627 /** 628 * <p>Returns the hash code value for this descriptor. The hash 629 * code is computed as the sum of the hash codes for each field in 630 * the descriptor. The hash code of a field with name {@code n} 631 * and value {@code v} is {@code n.toLowerCase().hashCode() ^ h}. 632 * Here {@code h} is the hash code of {@code v}, computed as 633 * follows:</p> 634 * 635 * <ul> 636 * <li>If {@code v} is null then {@code h} is 0.</li> 637 * <li>If {@code v} is a primitive array then {@code h} is computed using 638 * the appropriate overloading of {@code java.util.Arrays.hashCode}.</li> 639 * <li>If {@code v} is an object array then {@code h} is computed using 640 * {@link Arrays#deepHashCode(Object[])}.</li> 641 * <li>Otherwise {@code h} is {@code v.hashCode()}.</li> 642 * </ul> 643 * 644 * @return A hash code value for this object. 645 * 646 * @since 1.6 647 */ 648 public int hashCode(); 649} 650