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 */ 017package org.apache.commons.configuration2.beanutils; 018 019import java.beans.PropertyDescriptor; 020import java.lang.reflect.InvocationTargetException; 021import java.util.ArrayList; 022import java.util.Collection; 023import java.util.Collections; 024import java.util.HashMap; 025import java.util.List; 026import java.util.Map; 027import java.util.Set; 028import java.util.TreeSet; 029 030import org.apache.commons.beanutils.BeanUtilsBean; 031import org.apache.commons.beanutils.ConvertUtilsBean; 032import org.apache.commons.beanutils.DynaBean; 033import org.apache.commons.beanutils.FluentPropertyBeanIntrospector; 034import org.apache.commons.beanutils.PropertyUtilsBean; 035import org.apache.commons.beanutils.WrapDynaBean; 036import org.apache.commons.beanutils.WrapDynaClass; 037import org.apache.commons.configuration2.ex.ConfigurationRuntimeException; 038import org.apache.commons.lang3.ClassUtils; 039 040/** 041 * <p> 042 * A helper class for creating bean instances that are defined in configuration 043 * files. 044 * </p> 045 * <p> 046 * This class provides utility methods related to bean creation 047 * operations. These methods simplify such operations because a client need not 048 * deal with all involved interfaces. Usually, if a bean declaration has already 049 * been obtained, a single method call is necessary to create a new bean 050 * instance. 051 * </p> 052 * <p> 053 * This class also supports the registration of custom bean factories. 054 * Implementations of the {@link BeanFactory} interface can be 055 * registered under a symbolic name using the {@code registerBeanFactory()} 056 * method. In the configuration file the name of the bean factory can be 057 * specified in the bean declaration. Then this factory will be used to create 058 * the bean. 059 * </p> 060 * <p> 061 * In order to create beans using {@code BeanHelper}, create and instance of 062 * this class and initialize it accordingly - a default {@link BeanFactory} 063 * can be passed to the constructor, and additional bean factories can be 064 * registered (see above). Then this instance can be used to create beans from 065 * {@link BeanDeclaration} objects. {@code BeanHelper} is thread-safe. So an 066 * instance can be passed around in an application and shared between multiple 067 * components. 068 * </p> 069 * 070 * @since 1.3 071 * @version $Id: BeanHelper.java 1790899 2017-04-10 21:56:46Z ggregory $ 072 */ 073public final class BeanHelper 074{ 075 /** 076 * A default instance of {@code BeanHelper} which can be shared between 077 * arbitrary components. If no special configuration is needed, this 078 * instance can be used throughout an application. Otherwise, new instances 079 * can be created with their own configuration. 080 */ 081 public static final BeanHelper INSTANCE = new BeanHelper(); 082 083 /** 084 * A special instance of {@code BeanUtilsBean} which is used for all 085 * property set and copy operations. This instance was initialized with 086 * {@code BeanIntrospector} objects which support fluent interfaces. This is 087 * required for handling builder parameter objects correctly. 088 */ 089 private static final BeanUtilsBean BEAN_UTILS_BEAN = initBeanUtilsBean(); 090 091 /** Stores a map with the registered bean factories. */ 092 private final Map<String, BeanFactory> beanFactories = Collections 093 .synchronizedMap(new HashMap<String, BeanFactory>()); 094 095 /** 096 * Stores the default bean factory, which is used if no other factory 097 * is provided in a bean declaration. 098 */ 099 private final BeanFactory defaultBeanFactory; 100 101 /** 102 * Creates a new instance of {@code BeanHelper} with the default instance of 103 * {@link DefaultBeanFactory} as default {@link BeanFactory}. 104 */ 105 public BeanHelper() 106 { 107 this(null); 108 } 109 110 /** 111 * Creates a new instance of {@code BeanHelper} and sets the specified 112 * default {@code BeanFactory}. 113 * 114 * @param defFactory the default {@code BeanFactory} (can be <b>null</b>, 115 * then a default instance is used) 116 */ 117 public BeanHelper(BeanFactory defFactory) 118 { 119 defaultBeanFactory = 120 (defFactory != null) ? defFactory : DefaultBeanFactory.INSTANCE; 121 } 122 123 /** 124 * Register a bean factory under a symbolic name. This factory object can 125 * then be specified in bean declarations with the effect that this factory 126 * will be used to obtain an instance for the corresponding bean 127 * declaration. 128 * 129 * @param name the name of the factory 130 * @param factory the factory to be registered 131 */ 132 public void registerBeanFactory(String name, BeanFactory factory) 133 { 134 if (name == null) 135 { 136 throw new IllegalArgumentException( 137 "Name for bean factory must not be null!"); 138 } 139 if (factory == null) 140 { 141 throw new IllegalArgumentException("Bean factory must not be null!"); 142 } 143 144 beanFactories.put(name, factory); 145 } 146 147 /** 148 * Deregisters the bean factory with the given name. After that this factory 149 * cannot be used any longer. 150 * 151 * @param name the name of the factory to be deregistered 152 * @return the factory that was registered under this name; <b>null</b> if 153 * there was no such factory 154 */ 155 public BeanFactory deregisterBeanFactory(String name) 156 { 157 return beanFactories.remove(name); 158 } 159 160 /** 161 * Returns a set with the names of all currently registered bean factories. 162 * 163 * @return a set with the names of the registered bean factories 164 */ 165 public Set<String> registeredFactoryNames() 166 { 167 return beanFactories.keySet(); 168 } 169 170 /** 171 * Returns the default bean factory. 172 * 173 * @return the default bean factory 174 */ 175 public BeanFactory getDefaultBeanFactory() 176 { 177 return defaultBeanFactory; 178 } 179 180 /** 181 * Initializes the passed in bean. This method will obtain all the bean's 182 * properties that are defined in the passed in bean declaration. These 183 * properties will be set on the bean. If necessary, further beans will be 184 * created recursively. 185 * 186 * @param bean the bean to be initialized 187 * @param data the bean declaration 188 * @throws ConfigurationRuntimeException if a property cannot be set 189 */ 190 public void initBean(Object bean, BeanDeclaration data) 191 { 192 initBeanProperties(bean, data); 193 194 Map<String, Object> nestedBeans = data.getNestedBeanDeclarations(); 195 if (nestedBeans != null) 196 { 197 if (bean instanceof Collection) 198 { 199 // This is safe because the collection stores the values of the 200 // nested beans. 201 @SuppressWarnings("unchecked") 202 Collection<Object> coll = (Collection<Object>) bean; 203 if (nestedBeans.size() == 1) 204 { 205 Map.Entry<String, Object> e = nestedBeans.entrySet().iterator().next(); 206 String propName = e.getKey(); 207 Class<?> defaultClass = getDefaultClass(bean, propName); 208 if (e.getValue() instanceof List) 209 { 210 // This is safe, provided that the bean declaration is implemented 211 // correctly. 212 @SuppressWarnings("unchecked") 213 List<BeanDeclaration> decls = (List<BeanDeclaration>) e.getValue(); 214 for (BeanDeclaration decl : decls) 215 { 216 coll.add(createBean(decl, defaultClass)); 217 } 218 } 219 else 220 { 221 BeanDeclaration decl = (BeanDeclaration) e.getValue(); 222 coll.add(createBean(decl, defaultClass)); 223 } 224 } 225 } 226 else 227 { 228 for (Map.Entry<String, Object> e : nestedBeans.entrySet()) 229 { 230 String propName = e.getKey(); 231 Class<?> defaultClass = getDefaultClass(bean, propName); 232 233 Object prop = e.getValue(); 234 235 if (prop instanceof Collection) 236 { 237 Collection<Object> beanCollection = 238 createPropertyCollection(propName, defaultClass); 239 240 for (Object elemDef : (Collection<?>) prop) 241 { 242 beanCollection 243 .add(createBean((BeanDeclaration) elemDef)); 244 } 245 246 initProperty(bean, propName, beanCollection); 247 } 248 else 249 { 250 initProperty(bean, propName, createBean( 251 (BeanDeclaration) e.getValue(), defaultClass)); 252 } 253 } 254 } 255 } 256 } 257 258 /** 259 * Initializes the beans properties. 260 * 261 * @param bean the bean to be initialized 262 * @param data the bean declaration 263 * @throws ConfigurationRuntimeException if a property cannot be set 264 */ 265 public static void initBeanProperties(Object bean, BeanDeclaration data) 266 { 267 Map<String, Object> properties = data.getBeanProperties(); 268 if (properties != null) 269 { 270 for (Map.Entry<String, Object> e : properties.entrySet()) 271 { 272 String propName = e.getKey(); 273 initProperty(bean, propName, e.getValue()); 274 } 275 } 276 } 277 278 /** 279 * Creates a {@code DynaBean} instance which wraps the passed in bean. 280 * 281 * @param bean the bean to be wrapped (must not be <b>null</b>) 282 * @return a {@code DynaBean} wrapping the passed in bean 283 * @throws IllegalArgumentException if the bean is <b>null</b> 284 * @since 2.0 285 */ 286 public static DynaBean createWrapDynaBean(Object bean) 287 { 288 if (bean == null) 289 { 290 throw new IllegalArgumentException("Bean must not be null!"); 291 } 292 WrapDynaClass dynaClass = 293 WrapDynaClass.createDynaClass(bean.getClass(), 294 BEAN_UTILS_BEAN.getPropertyUtils()); 295 return new WrapDynaBean(bean, dynaClass); 296 } 297 298 /** 299 * Copies matching properties from the source bean to the destination bean 300 * using a specially configured {@code PropertyUtilsBean} instance. This 301 * method ensures that enhanced introspection is enabled when doing the copy 302 * operation. 303 * 304 * @param dest the destination bean 305 * @param orig the source bean 306 * @throws NoSuchMethodException exception thrown by 307 * {@code PropertyUtilsBean} 308 * @throws InvocationTargetException exception thrown by 309 * {@code PropertyUtilsBean} 310 * @throws IllegalAccessException exception thrown by 311 * {@code PropertyUtilsBean} 312 * @since 2.0 313 */ 314 public static void copyProperties(Object dest, Object orig) 315 throws IllegalAccessException, InvocationTargetException, 316 NoSuchMethodException 317 { 318 BEAN_UTILS_BEAN.getPropertyUtils().copyProperties(dest, orig); 319 } 320 321 /** 322 * Return the Class of the property if it can be determined. 323 * @param bean The bean containing the property. 324 * @param propName The name of the property. 325 * @return The class associated with the property or null. 326 */ 327 private static Class<?> getDefaultClass(Object bean, String propName) 328 { 329 try 330 { 331 PropertyDescriptor desc = 332 BEAN_UTILS_BEAN.getPropertyUtils().getPropertyDescriptor( 333 bean, propName); 334 if (desc == null) 335 { 336 return null; 337 } 338 return desc.getPropertyType(); 339 } 340 catch (Exception ex) 341 { 342 return null; 343 } 344 } 345 346 /** 347 * Sets a property on the given bean using Common Beanutils. 348 * 349 * @param bean the bean 350 * @param propName the name of the property 351 * @param value the property's value 352 * @throws ConfigurationRuntimeException if the property is not writeable or 353 * an error occurred 354 */ 355 private static void initProperty(Object bean, String propName, Object value) 356 { 357 if (!isPropertyWriteable(bean, propName)) 358 { 359 throw new ConfigurationRuntimeException("Property " + propName 360 + " cannot be set on " + bean.getClass().getName()); 361 } 362 363 try 364 { 365 BEAN_UTILS_BEAN.setProperty(bean, propName, value); 366 } 367 catch (IllegalAccessException iaex) 368 { 369 throw new ConfigurationRuntimeException(iaex); 370 } 371 catch (InvocationTargetException itex) 372 { 373 throw new ConfigurationRuntimeException(itex); 374 } 375 } 376 377 /** 378 * Creates a concrete collection instance to populate a property of type 379 * collection. This method tries to guess an appropriate collection type. 380 * Mostly the type of the property will be one of the collection interfaces 381 * rather than a concrete class; so we have to create a concrete equivalent. 382 * 383 * @param propName the name of the collection property 384 * @param propertyClass the type of the property 385 * @return the newly created collection 386 */ 387 private static Collection<Object> createPropertyCollection(String propName, 388 Class<?> propertyClass) 389 { 390 Collection<Object> beanCollection; 391 392 if (List.class.isAssignableFrom(propertyClass)) 393 { 394 beanCollection = new ArrayList<>(); 395 } 396 else if (Set.class.isAssignableFrom(propertyClass)) 397 { 398 beanCollection = new TreeSet<>(); 399 } 400 else 401 { 402 throw new UnsupportedOperationException( 403 "Unable to handle collection of type : " 404 + propertyClass.getName() + " for property " 405 + propName); 406 } 407 return beanCollection; 408 } 409 410 /** 411 * Set a property on the bean only if the property exists 412 * 413 * @param bean the bean 414 * @param propName the name of the property 415 * @param value the property's value 416 * @throws ConfigurationRuntimeException if the property is not writeable or 417 * an error occurred 418 */ 419 public static void setProperty(Object bean, String propName, Object value) 420 { 421 if (isPropertyWriteable(bean, propName)) 422 { 423 initProperty(bean, propName, value); 424 } 425 } 426 427 /** 428 * The main method for creating and initializing beans from a configuration. 429 * This method will return an initialized instance of the bean class 430 * specified in the passed in bean declaration. If this declaration does not 431 * contain the class of the bean, the passed in default class will be used. 432 * From the bean declaration the factory to be used for creating the bean is 433 * queried. The declaration may here return <b>null</b>, then a default 434 * factory is used. This factory is then invoked to perform the create 435 * operation. 436 * 437 * @param data the bean declaration 438 * @param defaultClass the default class to use 439 * @param param an additional parameter that will be passed to the bean 440 * factory; some factories may support parameters and behave different 441 * depending on the value passed in here 442 * @return the new bean 443 * @throws ConfigurationRuntimeException if an error occurs 444 */ 445 public Object createBean(BeanDeclaration data, Class<?> defaultClass, 446 Object param) 447 { 448 if (data == null) 449 { 450 throw new IllegalArgumentException( 451 "Bean declaration must not be null!"); 452 } 453 454 BeanFactory factory = fetchBeanFactory(data); 455 BeanCreationContext bcc = 456 createBeanCreationContext(data, defaultClass, param, factory); 457 try 458 { 459 return factory.createBean(bcc); 460 } 461 catch (Exception ex) 462 { 463 throw new ConfigurationRuntimeException(ex); 464 } 465 } 466 467 /** 468 * Returns a bean instance for the specified declaration. This method is a 469 * short cut for {@code createBean(data, null, null);}. 470 * 471 * @param data the bean declaration 472 * @param defaultClass the class to be used when in the declaration no class 473 * is specified 474 * @return the new bean 475 * @throws ConfigurationRuntimeException if an error occurs 476 */ 477 public Object createBean(BeanDeclaration data, Class<?> defaultClass) 478 { 479 return createBean(data, defaultClass, null); 480 } 481 482 /** 483 * Returns a bean instance for the specified declaration. This method is a 484 * short cut for {@code createBean(data, null);}. 485 * 486 * @param data the bean declaration 487 * @return the new bean 488 * @throws ConfigurationRuntimeException if an error occurs 489 */ 490 public Object createBean(BeanDeclaration data) 491 { 492 return createBean(data, null); 493 } 494 495 /** 496 * Returns a {@code java.lang.Class} object for the specified name. 497 * Because class loading can be tricky in some environments the code for 498 * retrieving a class by its name was extracted into this helper method. So 499 * if changes are necessary, they can be made at a single place. 500 * 501 * @param name the name of the class to be loaded 502 * @return the class object for the specified name 503 * @throws ClassNotFoundException if the class cannot be loaded 504 */ 505 static Class<?> loadClass(String name) throws ClassNotFoundException 506 { 507 return ClassUtils.getClass(name); 508 } 509 510 /** 511 * Checks whether the specified property of the given bean instance supports 512 * write access. 513 * 514 * @param bean the bean instance 515 * @param propName the name of the property in question 516 * @return <b>true</b> if this property can be written, <b>false</b> 517 * otherwise 518 */ 519 private static boolean isPropertyWriteable(Object bean, String propName) 520 { 521 return BEAN_UTILS_BEAN.getPropertyUtils().isWriteable(bean, propName); 522 } 523 524 /** 525 * Determines the class of the bean to be created. If the bean declaration 526 * contains a class name, this class is used. Otherwise it is checked 527 * whether a default class is provided. If this is not the case, the 528 * factory's default class is used. If this class is undefined, too, an 529 * exception is thrown. 530 * 531 * @param data the bean declaration 532 * @param defaultClass the default class 533 * @param factory the bean factory to use 534 * @return the class of the bean to be created 535 * @throws ConfigurationRuntimeException if the class cannot be determined 536 */ 537 private static Class<?> fetchBeanClass(BeanDeclaration data, 538 Class<?> defaultClass, BeanFactory factory) 539 { 540 String clsName = data.getBeanClassName(); 541 if (clsName != null) 542 { 543 try 544 { 545 return loadClass(clsName); 546 } 547 catch (ClassNotFoundException cex) 548 { 549 throw new ConfigurationRuntimeException(cex); 550 } 551 } 552 553 if (defaultClass != null) 554 { 555 return defaultClass; 556 } 557 558 Class<?> clazz = factory.getDefaultBeanClass(); 559 if (clazz == null) 560 { 561 throw new ConfigurationRuntimeException( 562 "Bean class is not specified!"); 563 } 564 return clazz; 565 } 566 567 /** 568 * Obtains the bean factory to use for creating the specified bean. This 569 * method will check whether a factory is specified in the bean declaration. 570 * If this is not the case, the default bean factory will be used. 571 * 572 * @param data the bean declaration 573 * @return the bean factory to use 574 * @throws ConfigurationRuntimeException if the factory cannot be determined 575 */ 576 private BeanFactory fetchBeanFactory(BeanDeclaration data) 577 { 578 String factoryName = data.getBeanFactoryName(); 579 if (factoryName != null) 580 { 581 BeanFactory factory = beanFactories.get(factoryName); 582 if (factory == null) 583 { 584 throw new ConfigurationRuntimeException( 585 "Unknown bean factory: " + factoryName); 586 } 587 else 588 { 589 return factory; 590 } 591 } 592 else 593 { 594 return getDefaultBeanFactory(); 595 } 596 } 597 598 /** 599 * Creates a {@code BeanCreationContext} object for the creation of the 600 * specified bean. 601 * 602 * @param data the bean declaration 603 * @param defaultClass the default class to use 604 * @param param an additional parameter that will be passed to the bean 605 * factory; some factories may support parameters and behave 606 * different depending on the value passed in here 607 * @param factory the current bean factory 608 * @return the {@code BeanCreationContext} 609 * @throws ConfigurationRuntimeException if the bean class cannot be 610 * determined 611 */ 612 private BeanCreationContext createBeanCreationContext( 613 final BeanDeclaration data, Class<?> defaultClass, 614 final Object param, BeanFactory factory) 615 { 616 final Class<?> beanClass = fetchBeanClass(data, defaultClass, factory); 617 return new BeanCreationContextImpl(this, beanClass, data, param); 618 } 619 620 /** 621 * Initializes the shared {@code BeanUtilsBean} instance. This method sets 622 * up custom bean introspection in a way that fluent parameter interfaces 623 * are supported. 624 * 625 * @return the {@code BeanUtilsBean} instance to be used for all property 626 * set operations 627 */ 628 private static BeanUtilsBean initBeanUtilsBean() 629 { 630 PropertyUtilsBean propUtilsBean = new PropertyUtilsBean(); 631 propUtilsBean.addBeanIntrospector(new FluentPropertyBeanIntrospector()); 632 return new BeanUtilsBean(new ConvertUtilsBean(), propUtilsBean); 633 } 634 635 /** 636 * An implementation of the {@code BeanCreationContext} interface used by 637 * {@code BeanHelper} to communicate with a {@code BeanFactory}. This class 638 * contains all information required for the creation of a bean. The methods 639 * for creating and initializing bean instances are implemented by calling 640 * back to the provided {@code BeanHelper} instance (which is the instance 641 * that created this object). 642 */ 643 private static final class BeanCreationContextImpl implements BeanCreationContext 644 { 645 /** The association BeanHelper instance. */ 646 private final BeanHelper beanHelper; 647 648 /** The class of the bean to be created. */ 649 private final Class<?> beanClass; 650 651 /** The underlying bean declaration. */ 652 private final BeanDeclaration data; 653 654 /** The parameter for the bean factory. */ 655 private final Object param; 656 657 private BeanCreationContextImpl(BeanHelper helper, Class<?> beanClass, 658 BeanDeclaration data, Object param) 659 { 660 beanHelper = helper; 661 this.beanClass = beanClass; 662 this.param = param; 663 this.data = data; 664 } 665 666 @Override 667 public void initBean(Object bean, BeanDeclaration data) 668 { 669 beanHelper.initBean(bean, data); 670 } 671 672 @Override 673 public Object getParameter() 674 { 675 return param; 676 } 677 678 @Override 679 public BeanDeclaration getBeanDeclaration() 680 { 681 return data; 682 } 683 684 @Override 685 public Class<?> getBeanClass() 686 { 687 return beanClass; 688 } 689 690 @Override 691 public Object createBean(BeanDeclaration data) 692 { 693 return beanHelper.createBean(data); 694 } 695 } 696}