001 /* ArrayType.java -- Open type descriptor for an array. 002 Copyright (C) 2006, 2007 Free Software Foundation, Inc. 003 004 This file is part of GNU Classpath. 005 006 GNU Classpath is free software; you can redistribute it and/or modify 007 it under the terms of the GNU General Public License as published by 008 the Free Software Foundation; either version 2, or (at your option) 009 any later version. 010 011 GNU Classpath is distributed in the hope that it will be useful, but 012 WITHOUT ANY WARRANTY; without even the implied warranty of 013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 014 General Public License for more details. 015 016 You should have received a copy of the GNU General Public License 017 along with GNU Classpath; see the file COPYING. If not, write to the 018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 019 02110-1301 USA. 020 021 Linking this library statically or dynamically with other modules is 022 making a combined work based on this library. Thus, the terms and 023 conditions of the GNU General Public License cover the whole 024 combination. 025 026 As a special exception, the copyright holders of this library give you 027 permission to link this library with independent modules to produce an 028 executable, regardless of the license terms of these independent 029 modules, and to copy and distribute the resulting executable under 030 terms of your choice, provided that you also meet, for each linked 031 independent module, the terms and conditions of the license of that 032 module. An independent module is a module which is not derived from 033 or based on this library. If you modify this library, you may extend 034 this exception to your version of the library, but you are not 035 obligated to do so. If you do not wish to do so, delete this 036 exception statement from your version. */ 037 038 package javax.management.openmbean; 039 040 import java.lang.reflect.Array; 041 042 import java.util.Arrays; 043 import java.util.HashMap; 044 import java.util.Map; 045 046 /** 047 * The open type descriptor for arrays of open data values. 048 * 049 * @author Andrew John Hughes (gnu_andrew@member.fsf.org) 050 * @since 1.5 051 */ 052 public class ArrayType<T> 053 extends OpenType<T> 054 { 055 056 /** 057 * Compatible with JDK 1.5 058 */ 059 private static final long serialVersionUID = 720504429830309770L; 060 061 /** 062 * The number of dimensions arrays of this type has. 063 */ 064 private int dimension; 065 066 /** 067 * The element type of arrays of this type. 068 */ 069 private OpenType<?> elementType; 070 071 /** 072 * True if this type represents a primitive array. 073 */ 074 private boolean primitiveArray; 075 076 /** 077 * The hash code of this instance. 078 */ 079 private transient Integer hashCode; 080 081 /** 082 * The <code>toString()</code> result of this instance. 083 */ 084 private transient String string; 085 086 /** 087 * A cache of {@link ArrayType} instances created 088 * by {@link #getArrayType(OpenType)}. 089 */ 090 private static final Map<OpenType<?>,ArrayType<?>> cache = 091 new HashMap<OpenType<?>,ArrayType<?>>(); 092 093 /** 094 * A cache of {@link ArrayType} instances created 095 * by {@link #getPrimitiveArrayType(Class)}. 096 */ 097 private static final Map<Class<?>,ArrayType<?>> primCache = 098 new HashMap<Class<?>,ArrayType<?>>(); 099 100 /** 101 * Returns the class name of the array, given the element 102 * class name and its dimensions. 103 * 104 * @param elementType the type of the array's elements. 105 * @param dim the dimensions of the array. 106 * @param primitive true if this should be a primitive array. 107 * @return the array's class name. 108 * @throws OpenDataException if the class name does not reference 109 * a loadable class. 110 */ 111 private static final String getArrayClassName(OpenType<?> elementType, 112 int dim, 113 boolean primitive) 114 throws OpenDataException 115 { 116 Class<?> type; 117 if (primitive) 118 type = getPrimitiveTypeClass((SimpleType<?>) elementType); 119 else 120 { 121 String className = elementType.getClassName(); 122 try 123 { 124 type = Class.forName(className); 125 } 126 catch (ClassNotFoundException e) 127 { 128 throw new OpenDataException("The class name, " + className + 129 ", is unavailable."); 130 } 131 } 132 while (type.isArray()) 133 type = type.getComponentType(); 134 return 135 Array.newInstance(type, 136 new int[getDimensions(elementType, dim)]).getClass().getName(); 137 } 138 139 /** 140 * Returns the dimensions of the new {@link ArrayType}, 141 * based on whether the given element type is already an 142 * {@link ArrayType} or not. 143 * 144 * @param elementType the type of the array. 145 * @param dim the proposed dimensions. 146 * @return the resultant dimensions. 147 * @throws IllegalArgumentException if <code>dim</code> is less than 1. 148 */ 149 private static final int getDimensions(OpenType<?> elementType, 150 int dim) 151 { 152 if (dim < 1) 153 throw new IllegalArgumentException("Dimensions must be greater " + 154 "than or equal to 1."); 155 if (elementType instanceof ArrayType) 156 return dim + ((ArrayType) elementType).getDimension(); 157 return dim; 158 } 159 160 /** 161 * Returns the appropriate primitive type name, given the 162 * corresponding wrapper class. 163 * 164 * @param type the type to convert. 165 * @return the corresponding primitive type. 166 * @throws OpenDataException if {@code type} is not a valid 167 * {@link Class} for a primitive type. 168 * 169 */ 170 private static final SimpleType<?> getPrimitiveType(Class<?> type) 171 throws OpenDataException 172 { 173 if (type.equals(Boolean.TYPE)) 174 return SimpleType.BOOLEAN; 175 if (type.equals(Byte.TYPE)) 176 return SimpleType.BYTE; 177 if (type.equals(Character.TYPE)) 178 return SimpleType.CHARACTER; 179 if (type.equals(Double.TYPE)) 180 return SimpleType.DOUBLE; 181 if (type.equals(Float.TYPE)) 182 return SimpleType.FLOAT; 183 if (type.equals(Integer.TYPE)) 184 return SimpleType.INTEGER; 185 if (type.equals(Long.TYPE)) 186 return SimpleType.LONG; 187 if (type.equals(Short.TYPE)) 188 return SimpleType.SHORT; 189 if (type.equals(Void.TYPE)) 190 return SimpleType.VOID; 191 throw new OpenDataException(type + " is not a primitive type."); 192 } 193 194 /** 195 * Returns the appropriate primitive type name, given the 196 * corresponding wrapper class. 197 * 198 * @param type the type to convert. 199 * @return the corresponding primitive type. 200 * @throws OpenDataException if {@code type} is not a valid 201 * {@link SimpleType} for a primitive type. 202 * 203 */ 204 private static final Class<?> getPrimitiveTypeClass(SimpleType<?> type) 205 throws OpenDataException 206 { 207 if (type.equals(SimpleType.BOOLEAN)) 208 return Boolean.TYPE; 209 if (type.equals(SimpleType.BYTE)) 210 return Byte.TYPE; 211 if (type.equals(SimpleType.CHARACTER)) 212 return Character.TYPE; 213 if (type.equals(SimpleType.DOUBLE)) 214 return Double.TYPE; 215 if (type.equals(SimpleType.FLOAT)) 216 return Float.TYPE; 217 if (type.equals(SimpleType.INTEGER)) 218 return Integer.TYPE; 219 if (type.equals(SimpleType.LONG)) 220 return Long.TYPE; 221 if (type.equals(SimpleType.SHORT)) 222 return Short.TYPE; 223 if (type.equals(SimpleType.VOID)) 224 return Void.TYPE; 225 throw new OpenDataException(type + " is not a primitive type."); 226 } 227 228 /** 229 * Returns the element type that will actually be used, if the 230 * specified element type is passed to a constructor. This is 231 * necessary to ensure that a non-array type is still returned when 232 * an {@link ArrayType} is constructed from an {@link ArrayType}. 233 * 234 * @param elemType the element type that was supplied. 235 * @return the element type that will be used. 236 */ 237 private static final OpenType<?> getElementType(OpenType<?> elemType) 238 { 239 if (elemType instanceof ArrayType) 240 return ((ArrayType) elemType).getElementOpenType(); 241 return elemType; 242 } 243 244 /** 245 * Returns the element type name that will actually be used, if the 246 * specified element type is passed to a constructor. This is 247 * necessary to ensure that a non-array type is still returned when 248 * an {@link ArrayType} is constructed from an {@link ArrayType}, 249 * and that primitive arrays are described correctly. 250 * 251 * @param elemType the element type that was supplied. 252 * @return the element type name that will be used. 253 * @throws OpenDataException if the element type is not a valid 254 * {@link SimpleType} for a primitive type. 255 */ 256 private static final String getElementTypeName(OpenType<?> elemType) 257 throws OpenDataException 258 { 259 OpenType<?> trueElemType = getElementType(elemType); 260 if (elemType instanceof ArrayType && 261 ((ArrayType) elemType).isPrimitiveArray()) 262 return getPrimitiveTypeClass((SimpleType<?>) trueElemType).getName(); 263 return trueElemType.getClassName(); 264 } 265 266 /** 267 * <p> 268 * Constructs a new {@link ArrayType} instance for an array of the 269 * specified type with the supplied number of dimensions. The attributes 270 * used by the superclass, {@link OpenType}, are automatically defined, 271 * based on these values. Both the class name and type name are set 272 * to the value returned by the {@link java.lang.Class#getName()} of 273 * the array's class (i.e. the element type, preceded by n instances of 274 * '[' and an 'L', where n is the number of dimensions the array has). 275 * The description is based upon the template <code>n-dimension array 276 * of e</code>, where n is the number of dimensions of the array, and 277 * e is the element type. The class name of the actual elements is 278 * obtainable by calling {@link OpenType#getClassName()} on the result 279 * of {@link #getElementOpenType()}. 280 * </p> 281 * <p> 282 * As an example, the array type returned by 283 * <code>new ArrayType(6, SimpleType.INTEGER)</code> has the following 284 * values: 285 * </p> 286 * <table> 287 * <th><td>Attribute</td><td>Value</td></th> 288 * <tr><td>Class Name</td><td><code>[[[[[[Ljava.lang.Integer;</code> 289 * </td></tr> 290 * <tr><td>Type Name</td><td><code>[[[[[[Ljava.lang.Integer;</code> 291 * </td></tr> 292 * <tr><td>Description</td><td><code>6-dimension array of 293 * java.lang.Integer</code></td></tr> 294 * <tr><td>Element Type Class Name</td><td><code>java.lang.Integer</code> 295 * </td></tr> 296 * </table> 297 * <p> 298 * The dimensions of the array must be equal to or greater than 1. The 299 * element type must be an instance of {@link SimpleType}, 300 * {@link CompositeType} or {@link TabularType}. 301 * </p> 302 * 303 * @param dim the dimensions of the array. 304 * @param elementType the type of the elements of the array. 305 * @throws IllegalArgumentException if <code>dim</code> is less than 1. 306 * @throws OpenDataException if the element type is not an instance of either 307 * {@link SimpleType}, {@link CompositeType} 308 * or {@link TabularType}. 309 */ 310 public ArrayType(int dim, OpenType<?> elementType) 311 throws OpenDataException 312 { 313 super(getArrayClassName(elementType, dim, false), 314 getArrayClassName(elementType, dim, false), 315 getDimensions(elementType, dim) + "-dimension array of " 316 + getElementTypeName(elementType)); 317 if (!(elementType instanceof SimpleType || 318 elementType instanceof CompositeType || 319 elementType instanceof TabularType || 320 elementType instanceof ArrayType)) 321 throw new OpenDataException("The element type must be a simple " + 322 "type, an array type, a composite type " + 323 "or a tabular type."); 324 dimension = getDimensions(elementType, dim); 325 this.elementType = getElementType(elementType); 326 primitiveArray = (elementType instanceof ArrayType && 327 ((ArrayType) elementType).isPrimitiveArray()); 328 } 329 330 /** 331 * <p> 332 * Constructs a new {@link ArrayType} instance for a unidimensional 333 * array of the specified {@link SimpleType}. The attributes 334 * used by the superclass, {@link OpenType}, are automatically defined, 335 * based on these values. Both the class name and type name are set 336 * to the value returned by the {@link java.lang.Class#getName()} of 337 * the array's class. If the array is of a primitive type (indicated 338 * by giving {@code primitiveArray} the value {@code true}), the 339 * name will be '[' followed by the appropriate letter for the 340 * primitive type (see {@link java.lang.Class#getName()}). If the 341 * array is not of a primitive type, then the name is formed from 342 * the element type, preceded by '[' and an 'L', in the same way 343 * as when the multi-dimensional constructor is used. 344 * </p> 345 * <p> 346 * The description is based upon the template <code>1-dimension array 347 * of e</code>, where e is either the primitive type or a class name, 348 * depending on whether the array itself is of a primitive type or not. 349 * The class name of the actual elements is obtainable by calling 350 * {@link OpenType#getClassName()} on the result of 351 * {@link #getElementOpenType()}. This will be the appropriate wrapper 352 * class for a primitive type. 353 * </p> 354 * <p> 355 * As an example, the array type returned by 356 * <code>new ArrayType(SimpleType.INTEGER, true)</code> has the following 357 * values: 358 * </p> 359 * <table> 360 * <th><td>Attribute</td><td>Value</td></th> 361 * <tr><td>Class Name</td><td><code>[I</code> 362 * </td></tr> 363 * <tr><td>Type Name</td><td><code>[I</code> 364 * </td></tr> 365 * <tr><td>Description</td><td><code>1-dimension array of int</code></td></tr> 366 * <tr><td>Element Type Class Name</td><td><code>java.lang.Integer</code> 367 * </td></tr> 368 * </table> 369 * 370 * @param elementType the type of the elements of the array. 371 * @param primitiveArray true if the array should be of a primitive type. 372 * @throws OpenDataException if {@code primitiveArray} is {@code true}, 373 * and {@link elementType} is not a valid 374 * {@link SimpleType} for a primitive type. 375 * @since 1.6 376 */ 377 public ArrayType(SimpleType<?> elementType, boolean primitiveArray) 378 throws OpenDataException 379 { 380 super(getArrayClassName(elementType, 1, primitiveArray), 381 getArrayClassName(elementType, 1, primitiveArray), 382 "1-dimension array of " + 383 (primitiveArray ? getPrimitiveTypeClass(elementType).getName() 384 : elementType.getClassName())); 385 dimension = 1; 386 this.elementType = elementType; 387 this.primitiveArray = primitiveArray; 388 } 389 390 /** 391 * <p> 392 * Compares this array type with another object 393 * for equality. The objects are judged to be equal if: 394 * </p> 395 * <ul> 396 * <li><code>obj</code> is not null.</li> 397 * <li><code>obj</code> is an instance of 398 * {@link ArrayType}.</li> 399 * <li>The dimensions are equal.</li> 400 * <li>The element types are equal.</li> 401 * <li>The primitive array flag is set the same in both 402 * instances.</li> 403 * </ul> 404 * 405 * @param obj the object to compare with. 406 * @return true if the conditions above hold. 407 */ 408 public boolean equals(Object obj) 409 { 410 if (!(obj instanceof ArrayType)) 411 return false; 412 ArrayType atype = (ArrayType) obj; 413 return (atype.getDimension() == dimension && 414 atype.getElementOpenType().equals(elementType) && 415 atype.isPrimitiveArray() == primitiveArray); 416 } 417 418 /** 419 * <p> 420 * Returns a new {@link ArrayType} instance in a type-safe 421 * manner, by ensuring that the type of the given {@link OpenType} 422 * matches the component type used in the type of the 423 * returned instance. If the given {@link OpenType} is a 424 * {@link SimpleType}, {@link CompositeType} or 425 * {@link TabularType}, then a 1-dimensional array of that 426 * type is returned. Otherwise, if the type is 427 * an {@link ArrayType} of n dimensions, the returned 428 * type is also an {@link ArrayType} but of n+1 dimensions. 429 * For example, 430 * {@code ArrayType.getArrayType(ArrayType.getArrayType(SimpleType.STRING))} 431 * returns a 2-dimensional array of {@link SimpleType#String}. 432 * </p> 433 * <p> 434 * This method caches its results, so that the same instance 435 * is returned from subsequent calls with the same parameters. 436 * </p> 437 * 438 * @param elementType the element type of the new array type. 439 * @throws OpenDataException if the class name of {@code elementType} 440 * is not in {@link OpenType#ALLOWED_CLASSNAMES_LIST}. 441 * @since 1.6 442 */ 443 public static <E> ArrayType<E[]> getArrayType(OpenType<E> elementType) 444 throws OpenDataException 445 { 446 ArrayType<E[]> arr = (ArrayType<E[]>) cache.get(elementType); 447 if (arr != null) 448 return arr; 449 arr = new ArrayType(1, elementType); 450 cache.put(elementType, arr); 451 return arr; 452 } 453 454 /** 455 * <p> 456 * Returns a new {@link ArrayType} instance for the given 457 * primitive type in a type-safe* manner, by ensuring that 458 * the type of the given {@link OpenType} matches the type 459 * used in the returned instance. If the type is 460 * an array of n dimensions, the returned 461 * type is also an {@link ArrayType} of n dimensions. 462 * </p> 463 * <p> 464 * As an example, the array type returned by 465 * <code>getPrimitiveArrayType(Integer.TYPE)</code> has the 466 * following values: 467 * </p> 468 * <table> 469 * <th><td>Attribute</td><td>Value</td></th> 470 * <tr><td>Class Name</td><td><code>[I</code> 471 * </td></tr> 472 * <tr><td>Type Name</td><td><code>[I</code> 473 * </td></tr> 474 * <tr><td>Description</td><td><code>1-dimension array of int</code></td></tr> 475 * <tr><td>Element Type Class Name</td><td><code>java.lang.Integer</code> 476 * </td></tr> 477 * </table> 478 * <p> 479 * This method caches its results, so that the same instance 480 * is returned from subsequent calls with the same parameters. 481 * </p> 482 * 483 * @param type the type of the new {@link ArrayType}. 484 * @throws IllegalArgumentException if the type is not a primitive 485 * array. 486 * @since 1.6 487 */ 488 public static <T> ArrayType<T> getPrimitiveArrayType(Class<T> type) 489 { 490 ArrayType<T> arr = (ArrayType<T>) primCache.get(type); 491 if (arr != null) 492 return arr; 493 Class<?> comType = type; 494 int dim = 0; 495 do 496 { 497 comType = comType.getComponentType(); 498 ++dim; 499 if (comType == null) 500 throw new IllegalArgumentException("The given class is " + 501 "not an array."); 502 } while (comType.isArray()); 503 String className = type.getName(); 504 try 505 { 506 arr = new ArrayType(getPrimitiveType(comType), true); 507 } 508 catch (OpenDataException e) 509 { 510 throw new IllegalArgumentException("The array is not of a primitive " + 511 "type", e); 512 } 513 while (dim > 1) 514 try 515 { 516 arr = new ArrayType(1, arr); 517 --dim; 518 } 519 catch (OpenDataException e) 520 { 521 throw (Error) 522 new InternalError("Couldn't generate extra dimensions").initCause(e); 523 } 524 primCache.put(type, arr); 525 return arr; 526 } 527 528 /** 529 * Returns the number of dimensions used by arrays 530 * of this type. 531 * 532 * @return the number of dimensions. 533 */ 534 public int getDimension() 535 { 536 return dimension; 537 } 538 539 /** 540 * Returns the open type descriptor which describes 541 * the type of the elements of this array type. 542 * 543 * @return the type of the elements. 544 */ 545 public OpenType<?> getElementOpenType() 546 { 547 return elementType; 548 } 549 550 /** 551 * <p> 552 * Returns the hash code of the array type. 553 * This is computed as the sum of the hash code of the 554 * element type together with the number of dimensions 555 * the array has and the primitive array flag. These 556 * are the same elements of the type that are compared as 557 * part of the {@link #equals(java.lang.Object)} method, 558 * thus ensuring that the hashcode is compatible with the 559 * equality test. 560 * </p> 561 * <p> 562 * As instances of this class are immutable, the hash code 563 * is computed just once for each instance and reused 564 * throughout its life. 565 * </p> 566 * 567 * @return the hash code of this instance. 568 */ 569 public int hashCode() 570 { 571 if (hashCode == null) 572 hashCode = Integer.valueOf(dimension + 573 elementType.hashCode() + 574 Boolean.valueOf(primitiveArray).hashCode()); 575 return hashCode.intValue(); 576 } 577 578 /** 579 * Returns true if this instance represents an array of 580 * a primitive type. 581 * 582 * @return true if the array is of a primitive type. 583 */ 584 public boolean isPrimitiveArray() 585 { 586 return primitiveArray; 587 } 588 589 /** 590 * <p> 591 * Returns true if the specified object is a member of this 592 * array type. The object is judged to be so if it is 593 * non-null, an array and one of the following two conditions 594 * holds: 595 * </p> 596 * <ul> 597 * <li>This {@link ArrayType} instance has a {@link SimpleType} 598 * as its element type. Thus, the object must have the same 599 * class name as that returned by {@link SimpleType#getClassName()} 600 * for this class.</li> 601 * <li>This {@link ArrayType} instance has a {@link CompositeType} 602 * or a {@link TabularType} as its element type. Thus, the object 603 * must be assignable to such an array, and have elements which 604 * are either null or valid values for the element type.</li> 605 * </ul> 606 * 607 * @param obj the object to test for membership. 608 * @return true if the object is a member of this type. 609 */ 610 public boolean isValue(Object obj) 611 { 612 if (obj == null) 613 return false; 614 Class objClass = obj.getClass(); 615 if (!(objClass.isArray())) 616 return false; 617 if (elementType instanceof SimpleType) 618 return getClassName().equals(objClass.getName()); 619 Class elementClass = null; 620 try 621 { 622 elementClass = Class.forName(getClassName()); 623 } 624 catch (ClassNotFoundException e) 625 { 626 throw new IllegalStateException("The array type's element " + 627 "class could not be found.", e); 628 } 629 if (!(elementClass.isAssignableFrom(objClass))) 630 return false; 631 for (int a = 0; a < Array.getLength(obj); ++a) 632 { 633 Object elem = Array.get(obj, a); 634 if (elem != null && 635 (!(elementType.isValue(elem)))) 636 return false; 637 } 638 return true; 639 } 640 641 /** 642 * <p> 643 * Returns a textual representation of this instance. This 644 * is constructed using the class name 645 * (<code>javax.management.openmbean.ArrayType</code>) 646 * and each element of the instance which is relevant to 647 * the definition of {@link equals(java.lang.Object)} and 648 * {@link hashCode()} (i.e. the type name, the number of 649 * dimensions and the element type). 650 * </p> 651 * <p> 652 * As instances of this class are immutable, the return value 653 * is computed just once for each instance and reused 654 * throughout its life. 655 * </p> 656 * 657 * @return a @link{java.lang.String} instance representing 658 * the instance in textual form. 659 */ 660 public String toString() 661 { 662 if (string == null) 663 string = getClass().getName() 664 + "[name=" + getTypeName() 665 + ", dimension=" + dimension 666 + ", elementType=" + elementType 667 + ", primitiveArray=" + primitiveArray 668 + "]"; 669 return string; 670 } 671 672 }