001 /* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017 package org.apache.commons.beanutils; 018 019 import java.util.ArrayList; 020 import java.util.Map; 021 import java.util.Collection; 022 import java.util.Iterator; 023 import java.lang.reflect.Array; 024 025 /** 026 * <h2><i>Lazy</i> DynaBean List.</h2> 027 * 028 * <p>There are two main purposes for this class:</p> 029 * <ul> 030 * <li>To provide <i>Lazy List</i> behaviour - automatically 031 * <i>growing</i> and <i>populating</i> the <code>List</code> 032 * with either <code>DynaBean</code>, <code>java.util.Map</code> 033 * or POJO Beans.</li> 034 * <li>To provide a straight forward way of putting a Collection 035 * or Array into the lazy list <i>and</i> a straight forward 036 * way to get it out again at the end.</li> 037 * </ul> 038 * 039 * <p>All elements added to the List are stored as <code>DynaBean</code>'s:</p> 040 * <ul> 041 * <li><code>java.util.Map</code> elements are "wrapped" in a <code>LazyDynaMap</code>.</i> 042 * <li>POJO Bean elements are "wrapped" in a <code>WrapDynaBean.</code></i> 043 * <li><code>DynaBean</code>'s are stored un-changed.</i> 044 * </ul> 045 * 046 * <h4><code>toArray()</code></h4> 047 * <p>The <code>toArray()</code> method returns an array of the 048 * elements of the appropriate type. If the <code>LazyDynaList</code> 049 * is populated with <code>java.util.Map</code> objects a 050 * <code>Map[]</code> array is returned. 051 * If the list is populated with POJO Beans an appropriate 052 * array of the POJO Beans is returned. Otherwise a <code>DynaBean[]</code> 053 * array is returned. 054 * </p> 055 * 056 * <h4><code>toDynaBeanArray()</code></h4> 057 * <p>The <code>toDynaBeanArray()</code> method returns a 058 * <code>DynaBean[]</code> array of the elements in the List. 059 * </p> 060 * 061 * <p><strong>N.B.</strong>All the elements in the List must be the 062 * same type. If the <code>DynaClass</code> or <code>Class</code> 063 * of the <code>LazyDynaList</code>'s elements is 064 * not specified, then it will be automatically set to the type 065 * of the first element populated. 066 * </p> 067 * 068 * <h3>Example 1</h3> 069 * <p>If you have an array of <code>java.util.Map[]</code> - you can put that into 070 * a <code>LazyDynaList</code>.</p> 071 * 072 * <pre><code> 073 * TreeMap[] myArray = .... // your Map[] 074 * List lazyList = new LazyDynaList(myArray); 075 * </code></pre> 076 * 077 * <p>New elements of the appropriate Map type are 078 * automatically populated:</p> 079 * 080 * <pre><code> 081 * // get(index) automatically grows the list 082 * DynaBean newElement = (DynaBean)lazyList.get(lazyList.size()); 083 * newElement.put("someProperty", "someValue"); 084 * </code></pre> 085 * 086 * <p>Once you've finished you can get back an Array of the 087 * elements of the appropriate type:</p> 088 * 089 * <pre><code> 090 * // Retrieve the array from the list 091 * TreeMap[] myArray = (TreeMap[])lazyList.toArray()); 092 * </code></pre> 093 * 094 * 095 * <h3>Example 2</h3> 096 * <p>Alternatively you can create an <i>empty</i> List and 097 * specify the Class for List's elements. The LazyDynaList 098 * uses the Class to automatically populate elements:</p> 099 * 100 * <pre><code> 101 * // e.g. For Maps 102 * List lazyList = new LazyDynaList(TreeMap.class); 103 * 104 * // e.g. For POJO Beans 105 * List lazyList = new LazyDynaList(MyPojo.class); 106 * 107 * // e.g. For DynaBeans 108 * List lazyList = new LazyDynaList(MyDynaBean.class); 109 * </code></pre> 110 * 111 * <h3>Example 3</h3> 112 * <p>Alternatively you can create an <i>empty</i> List and specify the 113 * DynaClass for List's elements. The LazyDynaList uses 114 * the DynaClass to automatically populate elements:</p> 115 * 116 * <pre><code> 117 * // e.g. For Maps 118 * DynaClass dynaClass = new LazyDynaMap(new HashMap()); 119 * List lazyList = new LazyDynaList(dynaClass); 120 * 121 * // e.g. For POJO Beans 122 * DynaClass dynaClass = (new WrapDynaBean(myPojo)).getDynaClass(); 123 * List lazyList = new LazyDynaList(dynaClass); 124 * 125 * // e.g. For DynaBeans 126 * DynaClass dynaClass = new BasicDynaClass(properties); 127 * List lazyList = new LazyDynaList(dynaClass); 128 * </code></pre> 129 * 130 * <p><strong>N.B.</strong> You may wonder why control the type 131 * using a <code>DynaClass</code> rather than the <code>Class</code> 132 * as in the previous example - the reason is that some <code>DynaBean</code> 133 * implementations don't have a <i>default</i> empty constructor and 134 * therefore need to be instantiated using the <code>DynaClass.newInstance()</code> 135 * method.</p> 136 * 137 * <h3>Example 4</h3> 138 * <p>A slight variation - set the element type using either 139 * the <code>setElementType(Class)</code> method or the 140 * <code>setElementDynaClass(DynaClass)</code> method - then populate 141 * with the normal <code>java.util.List</code> methods(i.e. 142 * <code>add()</code>, <code>addAll()</code> or <code>set()</code>).</p> 143 * 144 * <pre><code> 145 * // Create a new LazyDynaList (100 element capacity) 146 * LazyDynaList lazyList = new LazyDynaList(100); 147 * 148 * // Either Set the element type... 149 * lazyList.setElementType(TreeMap.class); 150 * 151 * // ...or the element DynaClass... 152 * lazyList.setElementDynaClass(new MyCustomDynaClass()); 153 * 154 * // Populate from a collection 155 * lazyList.addAll(myCollection); 156 * 157 * </code></pre> 158 * 159 * @author Niall Pemberton 160 * @version $Revision: 555824 $ $Date: 2007-07-13 01:27:15 +0100 (Fri, 13 Jul 2007) $ 161 */ 162 public class LazyDynaList extends ArrayList { 163 164 /** 165 * The DynaClass of the List's elements. 166 */ 167 private DynaClass elementDynaClass; 168 169 /** 170 * The WrapDynaClass if the List's contains 171 * POJO Bean elements. 172 * 173 * N.B. WrapDynaClass isn't serlializable, which 174 * is why its stored separately in a 175 * transient instance variable. 176 */ 177 private transient WrapDynaClass wrapDynaClass; 178 179 /** 180 * The type of the List's elements. 181 */ 182 private Class elementType; 183 184 /** 185 * The DynaBean type of the List's elements. 186 */ 187 private Class elementDynaBeanType; 188 189 190 // ------------------- Constructors ------------------------------ 191 192 /** 193 * Default Constructor. 194 */ 195 public LazyDynaList() { 196 super(); 197 } 198 199 /** 200 * Construct a LazyDynaList with the 201 * specified capacity. 202 * 203 * @param capacity The initial capacity of the list. 204 */ 205 public LazyDynaList(int capacity) { 206 super(capacity); 207 208 } 209 210 /** 211 * Construct a LazyDynaList with a 212 * specified DynaClass for its elements. 213 * 214 * @param elementDynaClass The DynaClass of the List's elements. 215 */ 216 public LazyDynaList(DynaClass elementDynaClass) { 217 super(); 218 setElementDynaClass(elementDynaClass); 219 } 220 221 /** 222 * Construct a LazyDynaList with a 223 * specified type for its elements. 224 * 225 * @param elementType The Type of the List's elements. 226 */ 227 public LazyDynaList(Class elementType) { 228 super(); 229 setElementType(elementType); 230 } 231 232 /** 233 * Construct a LazyDynaList populated with the 234 * elements of a Collection. 235 * 236 * @param collection The Collection to poulate the List from. 237 */ 238 public LazyDynaList(Collection collection) { 239 super(collection.size()); 240 addAll(collection); 241 } 242 243 /** 244 * Construct a LazyDynaList populated with the 245 * elements of an Array. 246 * 247 * @param array The Array to poulate the List from. 248 */ 249 public LazyDynaList(Object[] array) { 250 super(array.length); 251 for (int i = 0; i < array.length; i++) { 252 add(array[i]); 253 } 254 } 255 256 257 // ------------------- java.util.List Methods -------------------- 258 259 /** 260 * <p>Insert an element at the specified index position.</p> 261 * 262 * <p>If the index position is greater than the current 263 * size of the List, then the List is automatically 264 * <i>grown</i> to the appropriate size.</p> 265 * 266 * @param index The index position to insert the new element. 267 * @param element The new element to add. 268 */ 269 public void add(int index, Object element) { 270 271 DynaBean dynaBean = transform(element); 272 273 growList(index); 274 275 super.add(index, dynaBean); 276 277 } 278 279 /** 280 * <p>Add an element to the List.</p> 281 * 282 * @param element The new element to add. 283 * @return true. 284 */ 285 public boolean add(Object element) { 286 287 DynaBean dynaBean = transform(element); 288 289 return super.add(dynaBean); 290 291 } 292 293 /** 294 * <p>Add all the elements from a Collection to the list. 295 * 296 * @param collection The Collection of new elements. 297 * @return true if elements were added. 298 */ 299 public boolean addAll(Collection collection) { 300 301 if (collection == null || collection.size() == 0) { 302 return false; 303 } 304 305 ensureCapacity(size() + collection.size()); 306 307 Iterator iterator = collection.iterator(); 308 while (iterator.hasNext()) { 309 add(iterator.next()); 310 } 311 312 return true; 313 314 } 315 316 /** 317 * <p>Insert all the elements from a Collection into the 318 * list at a specified position. 319 * 320 * <p>If the index position is greater than the current 321 * size of the List, then the List is automatically 322 * <i>grown</i> to the appropriate size.</p> 323 * 324 * @param collection The Collection of new elements. 325 * @param index The index position to insert the new elements at. 326 * @return true if elements were added. 327 */ 328 public boolean addAll(int index, Collection collection) { 329 330 if (collection == null || collection.size() == 0) { 331 return false; 332 } 333 334 ensureCapacity((index > size() ? index : size()) + collection.size()); 335 336 // Call "tranform" with first element, before 337 // List is "grown" to ensure the correct DynaClass 338 // is set. 339 if (size() == 0) { 340 transform(collection.iterator().next()); 341 } 342 343 growList(index); 344 345 Iterator iterator = collection.iterator(); 346 while (iterator.hasNext()) { 347 add(index++, iterator.next()); 348 } 349 350 return true; 351 352 } 353 354 /** 355 * <p>Return the element at the specified position.</p> 356 * 357 * <p>If the position requested is greater than the current 358 * size of the List, then the List is automatically 359 * <i>grown</i> (and populated) to the appropriate size.</p> 360 * 361 * @param index The index position to insert the new elements at. 362 * @return The element at the specified position. 363 */ 364 public Object get(int index) { 365 366 growList(index + 1); 367 368 return super.get(index); 369 370 } 371 372 /** 373 * <p>Set the element at the specified position.</p> 374 * 375 * <p>If the position requested is greater than the current 376 * size of the List, then the List is automatically 377 * <i>grown</i> (and populated) to the appropriate size.</p> 378 * 379 * @param index The index position to insert the new element at. 380 * @param element The new element. 381 * @return The new element. 382 */ 383 public Object set(int index, Object element) { 384 385 DynaBean dynaBean = transform(element); 386 387 growList(index + 1); 388 389 return super.set(index, dynaBean); 390 391 } 392 393 /** 394 * <p>Converts the List to an Array.</p> 395 * 396 * <p>The type of Array created depends on the contents 397 * of the List:</p> 398 * <ul> 399 * <li>If the List contains only LazyDynaMap type elements 400 * then a java.util.Map[] array will be created.</li> 401 * <li>If the List contains only elements which are 402 * "wrapped" DynaBeans then an Object[] of the most 403 * suitable type will be created.</li> 404 * <li>...otherwise a DynaBean[] will be created.</li> 405 * 406 * @return An Array of the elements in this List. 407 */ 408 public Object[] toArray() { 409 410 if (size() == 0 && elementType == null) { 411 return new LazyDynaBean[0]; 412 } 413 414 Object[] array = (Object[])Array.newInstance(elementType, size()); 415 for (int i = 0; i < size(); i++) { 416 if (Map.class.isAssignableFrom(elementType)) { 417 array[i] = ((LazyDynaMap)get(i)).getMap(); 418 } else if (DynaBean.class.isAssignableFrom(elementType)) { 419 array[i] = (DynaBean)get(i); 420 } else { 421 array[i] = ((WrapDynaBean)get(i)).getInstance(); 422 } 423 } 424 return array; 425 426 } 427 428 /** 429 * <p>Converts the List to an Array of the specified type.</p> 430 * 431 * @param model The model for the type of array to return 432 * @return An Array of the elements in this List. 433 */ 434 public Object[] toArray(Object[] model) { 435 436 // Allocate the Array 437 Class arrayType = model.getClass().getComponentType(); 438 Object[] array = (Object[])Array.newInstance(arrayType, size()); 439 440 if (size() == 0 && elementType == null) { 441 return new LazyDynaBean[0]; 442 } 443 444 if ((DynaBean.class.isAssignableFrom(arrayType))) { 445 for (int i = 0; i < size(); i++) { 446 array[i] = get(i); 447 } 448 return array; 449 } 450 451 if ((arrayType.isAssignableFrom(elementType))) { 452 for (int i = 0; i < size(); i++) { 453 if (Map.class.isAssignableFrom(elementType)) { 454 array[i] = ((LazyDynaMap)get(i)).getMap(); 455 } else if (DynaBean.class.isAssignableFrom(elementType)) { 456 array[i] = get(i); 457 } else { 458 array[i] = ((WrapDynaBean)get(i)).getInstance(); 459 } 460 } 461 return array; 462 } 463 464 throw new IllegalArgumentException("Invalid array type: " 465 + arrayType.getName() + " - not compatible with '" 466 + elementType.getName()); 467 468 } 469 470 471 // ------------------- Public Methods ---------------------------- 472 473 /** 474 * <p>Converts the List to an DynaBean Array.</p> 475 * 476 * @return A DynaBean[] of the elements in this List. 477 */ 478 public DynaBean[] toDynaBeanArray() { 479 480 if (size() == 0 && elementDynaBeanType == null) { 481 return new LazyDynaBean[0]; 482 } 483 484 DynaBean[] array = (DynaBean[])Array.newInstance(elementDynaBeanType, size()); 485 for (int i = 0; i < size(); i++) { 486 array[i] = (DynaBean)get(i); 487 } 488 return array; 489 490 } 491 492 /** 493 * <p>Set the element Type and DynaClass.</p> 494 * 495 * @param elementType The type of the elements. 496 * @exception IllegalArgumentException if the List already 497 * contains elements or the DynaClass is null. 498 */ 499 public void setElementType(Class elementType) { 500 501 if (elementType == null) { 502 throw new IllegalArgumentException("Element Type is missing"); 503 } 504 505 if (size() > 0) { 506 throw new IllegalStateException("Element Type cannot be reset"); 507 } 508 509 this.elementType = elementType; 510 511 // Create a new object of the specified type 512 Object object = null; 513 try { 514 object = elementType.newInstance(); 515 } catch (Exception e) { 516 throw new IllegalArgumentException("Error creating type: " 517 + elementType.getName() + " - " + e); 518 } 519 520 // Create a DynaBean 521 DynaBean dynaBean = null; 522 if (Map.class.isAssignableFrom(elementType)) { 523 dynaBean = new LazyDynaMap((Map)object); 524 this.elementDynaClass = dynaBean.getDynaClass(); 525 } else if (DynaBean.class.isAssignableFrom(elementType)) { 526 dynaBean = (DynaBean)object; 527 this.elementDynaClass = dynaBean.getDynaClass(); 528 } else { 529 dynaBean = new WrapDynaBean(object); 530 this.wrapDynaClass = (WrapDynaClass)dynaBean.getDynaClass(); 531 } 532 533 this.elementDynaBeanType = dynaBean.getClass(); 534 535 // Re-calculate the type 536 if (WrapDynaBean.class.isAssignableFrom(elementDynaBeanType )) { 537 this.elementType = ((WrapDynaBean)dynaBean).getInstance().getClass(); 538 } else if (LazyDynaMap.class.isAssignableFrom(elementDynaBeanType )) { 539 this.elementType = ((LazyDynaMap)dynaBean).getMap().getClass(); 540 } 541 542 } 543 544 /** 545 * <p>Set the element Type and DynaClass.</p> 546 * 547 * @param elementDynaClass The DynaClass of the elements. 548 * @exception IllegalArgumentException if the List already 549 * contains elements or the DynaClass is null. 550 */ 551 public void setElementDynaClass(DynaClass elementDynaClass) { 552 553 if (elementDynaClass == null) { 554 throw new IllegalArgumentException("Element DynaClass is missing"); 555 } 556 557 if (size() > 0) { 558 throw new IllegalStateException("Element DynaClass cannot be reset"); 559 } 560 561 // Try to create a new instance of the DynaBean 562 try { 563 DynaBean dynaBean = elementDynaClass.newInstance(); 564 this.elementDynaBeanType = dynaBean.getClass(); 565 if (WrapDynaBean.class.isAssignableFrom(elementDynaBeanType)) { 566 this.elementType = ((WrapDynaBean)dynaBean).getInstance().getClass(); 567 this.wrapDynaClass = (WrapDynaClass)elementDynaClass; 568 } else if (LazyDynaMap.class.isAssignableFrom(elementDynaBeanType)) { 569 this.elementType = ((LazyDynaMap)dynaBean).getMap().getClass(); 570 this.elementDynaClass = elementDynaClass; 571 } else { 572 this.elementType = dynaBean.getClass(); 573 this.elementDynaClass = elementDynaClass; 574 } 575 } catch (Exception e) { 576 throw new IllegalArgumentException( 577 "Error creating DynaBean from " + 578 elementDynaClass.getClass().getName() + " - " + e); 579 } 580 581 } 582 583 584 // ------------------- Private Methods --------------------------- 585 586 /** 587 * <p>Automatically <i>grown</i> the List 588 * to the appropriate size, populating with 589 * DynaBeans.</p> 590 * 591 * @param requiredSize the required size of the List. 592 */ 593 private void growList(int requiredSize) { 594 595 if (requiredSize < size()) { 596 return; 597 } 598 599 ensureCapacity(requiredSize + 1); 600 601 for (int i = size(); i < requiredSize; i++) { 602 DynaBean dynaBean = transform(null); 603 super.add(dynaBean); 604 } 605 606 } 607 608 /** 609 * <p>Transform the element into a DynaBean:</p> 610 * 611 * <ul> 612 * <li>Map elements are turned into LazyDynaMap's.</li> 613 * <li>POJO Beans are "wrapped" in a WrapDynaBean.</li> 614 * <li>DynaBeans are unchanged.</li> 615 * </li> 616 * 617 * @param element The element to transformt. 618 * @param The DynaBean to store in the List. 619 */ 620 private DynaBean transform(Object element) { 621 622 DynaBean dynaBean = null; 623 Class newDynaBeanType = null; 624 Class newElementType = null; 625 626 // Create a new element 627 if (element == null) { 628 629 // Default Types to LazyDynaBean 630 // if not specified 631 if (elementType == null) { 632 setElementDynaClass(new LazyDynaClass()); 633 } 634 635 // Get DynaClass (restore WrapDynaClass lost in serialization) 636 DynaClass dynaClass = (elementDynaClass == null) ? wrapDynaClass : elementDynaClass; 637 if (dynaClass == null) { 638 setElementType(elementType); 639 } 640 641 // Create a new DynaBean 642 try { 643 dynaBean = dynaClass.newInstance(); 644 newDynaBeanType = dynaBean.getClass(); 645 } catch (Exception e) { 646 throw new IllegalArgumentException("Error creating DynaBean: " 647 + dynaClass.getClass().getName() 648 + " - " + e); 649 } 650 651 } else { 652 653 // Transform Object to a DynaBean 654 newElementType = element.getClass(); 655 if (Map.class.isAssignableFrom(element.getClass())) { 656 dynaBean = new LazyDynaMap((Map)element); 657 } else if (DynaBean.class.isAssignableFrom(element.getClass())) { 658 dynaBean = (DynaBean)element; 659 } else { 660 dynaBean = new WrapDynaBean(element); 661 } 662 663 newDynaBeanType = dynaBean.getClass(); 664 665 } 666 667 // Re-calculate the element type 668 newElementType = dynaBean.getClass(); 669 if (WrapDynaBean.class.isAssignableFrom(newDynaBeanType)) { 670 newElementType = ((WrapDynaBean)dynaBean).getInstance().getClass(); 671 } else if (LazyDynaMap.class.isAssignableFrom(newDynaBeanType)) { 672 newElementType = ((LazyDynaMap)dynaBean).getMap().getClass(); 673 } 674 675 // Check the new element type, matches all the 676 // other elements in the List 677 if (newElementType != elementType) { 678 throw new IllegalArgumentException("Element Type " + newElementType 679 + " doesn't match other elements " + elementType); 680 } 681 682 return dynaBean; 683 684 } 685 686 }