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.configuration.beanutils; 018 019 import java.util.ArrayList; 020 import java.util.HashMap; 021 import java.util.Iterator; 022 import java.util.List; 023 import java.util.Map; 024 025 import org.apache.commons.configuration.ConfigurationRuntimeException; 026 import org.apache.commons.configuration.HierarchicalConfiguration; 027 import org.apache.commons.configuration.PropertyConverter; 028 import org.apache.commons.configuration.SubnodeConfiguration; 029 import org.apache.commons.configuration.tree.ConfigurationNode; 030 import org.apache.commons.configuration.tree.DefaultConfigurationNode; 031 032 /** 033 * <p> 034 * An implementation of the {@code BeanDeclaration} interface that is 035 * suitable for XML configuration files. 036 * </p> 037 * <p> 038 * This class defines the standard layout of a bean declaration in an XML 039 * configuration file. Such a declaration must look like the following example 040 * fragment: 041 * </p> 042 * <p> 043 * 044 * <pre> 045 * ... 046 * <personBean config-class="my.model.PersonBean" 047 * lastName="Doe" firstName="John"> 048 * <address config-class="my.model.AddressBean" 049 * street="21st street 11" zip="1234" 050 * city="TestCity"/> 051 * </personBean> 052 * </pre> 053 * 054 * </p> 055 * <p> 056 * The bean declaration can be contained in an arbitrary element. Here it is the 057 * {@code personBean} element. In the attributes of this element 058 * there can occur some reserved attributes, which have the following meaning: 059 * <dl> 060 * <dt>{@code config-class}</dt> 061 * <dd>Here the full qualified name of the bean's class can be specified. An 062 * instance of this class will be created. If this attribute is not specified, 063 * the bean class must be provided in another way, e.g. as the 064 * {@code defaultClass} passed to the {@code BeanHelper} class.</dd> 065 * <dt>{@code config-factory}</dt> 066 * <dd>This attribute can contain the name of the 067 * {@link BeanFactory} that should be used for creating the bean. 068 * If it is defined, a factory with this name must have been registered at the 069 * {@code BeanHelper} class. If this attribute is missing, the default 070 * bean factory will be used.</dd> 071 * <dt>{@code config-factoryParam}</dt> 072 * <dd>With this attribute a parameter can be specified that will be passed to 073 * the bean factory. This may be useful for custom bean factories.</dd> 074 * </dl> 075 * </p> 076 * <p> 077 * All further attributes starting with the {@code config-} prefix are 078 * considered as meta data and will be ignored. All other attributes are treated 079 * as properties of the bean to be created, i.e. corresponding setter methods of 080 * the bean will be invoked with the values specified here. 081 * </p> 082 * <p> 083 * If the bean to be created has also some complex properties (which are itself 084 * beans), their values cannot be initialized from attributes. For this purpose 085 * nested elements can be used. The example listing shows how an address bean 086 * can be initialized. This is done in a nested element whose name must match 087 * the name of a property of the enclosing bean declaration. The format of this 088 * nested element is exactly the same as for the bean declaration itself, i.e. 089 * it can have attributes defining meta data or bean properties and even further 090 * nested elements for complex bean properties. 091 * </p> 092 * <p> 093 * A {@code XMLBeanDeclaration} object is usually created from a 094 * {@code HierarchicalConfiguration}. From this it will derive a 095 * {@code SubnodeConfiguration}, which is used to access the needed 096 * properties. This subnode configuration can be obtained using the 097 * {@link #getConfiguration()} method. All of its properties can 098 * be accessed in the usual way. To ensure that the property keys used by this 099 * class are understood by the configuration, the default expression engine will 100 * be set. 101 * </p> 102 * 103 * @since 1.3 104 * @author <a 105 * href="http://commons.apache.org/configuration/team-list.html">Commons 106 * Configuration team</a> 107 * @version $Id: XMLBeanDeclaration.java 1208761 2011-11-30 20:39:47Z oheger $ 108 */ 109 public class XMLBeanDeclaration implements BeanDeclaration 110 { 111 /** Constant for the prefix of reserved attributes. */ 112 public static final String RESERVED_PREFIX = "config-"; 113 114 /** Constant for the prefix for reserved attributes.*/ 115 public static final String ATTR_PREFIX = "[@" + RESERVED_PREFIX; 116 117 /** Constant for the bean class attribute. */ 118 public static final String ATTR_BEAN_CLASS = ATTR_PREFIX + "class]"; 119 120 /** Constant for the bean factory attribute. */ 121 public static final String ATTR_BEAN_FACTORY = ATTR_PREFIX + "factory]"; 122 123 /** Constant for the bean factory parameter attribute. */ 124 public static final String ATTR_FACTORY_PARAM = ATTR_PREFIX 125 + "factoryParam]"; 126 127 /** Stores the associated configuration. */ 128 private SubnodeConfiguration configuration; 129 130 /** Stores the configuration node that contains the bean declaration. */ 131 private ConfigurationNode node; 132 133 /** 134 * Creates a new instance of {@code XMLBeanDeclaration} and 135 * initializes it from the given configuration. The passed in key points to 136 * the bean declaration. 137 * 138 * @param config the configuration 139 * @param key the key to the bean declaration (this key must point to 140 * exactly one bean declaration or a {@code IllegalArgumentException} 141 * exception will be thrown) 142 */ 143 public XMLBeanDeclaration(HierarchicalConfiguration config, String key) 144 { 145 this(config, key, false); 146 } 147 148 /** 149 * Creates a new instance of {@code XMLBeanDeclaration} and 150 * initializes it from the given configuration. The passed in key points to 151 * the bean declaration. If the key does not exist and the boolean argument 152 * is <b>true</b>, the declaration is initialized with an empty 153 * configuration. It is possible to create objects from such an empty 154 * declaration if a default class is provided. If the key on the other hand 155 * has multiple values or is undefined and the boolean argument is <b>false</b>, 156 * a {@code IllegalArgumentException} exception will be thrown. 157 * 158 * @param config the configuration 159 * @param key the key to the bean declaration 160 * @param optional a flag whether this declaration is optional; if set to 161 * <b>true</b>, no exception will be thrown if the passed in key is 162 * undefined 163 */ 164 public XMLBeanDeclaration(HierarchicalConfiguration config, String key, 165 boolean optional) 166 { 167 if (config == null) 168 { 169 throw new IllegalArgumentException( 170 "Configuration must not be null!"); 171 } 172 173 try 174 { 175 configuration = config.configurationAt(key); 176 node = configuration.getRootNode(); 177 } 178 catch (IllegalArgumentException iex) 179 { 180 // If we reach this block, the key does not have exactly one value 181 if (!optional || config.getMaxIndex(key) > 0) 182 { 183 throw iex; 184 } 185 configuration = config.configurationAt(null); 186 node = new DefaultConfigurationNode(); 187 } 188 initSubnodeConfiguration(getConfiguration()); 189 } 190 191 /** 192 * Creates a new instance of {@code XMLBeanDeclaration} and 193 * initializes it from the given configuration. The configuration's root 194 * node must contain the bean declaration. 195 * 196 * @param config the configuration with the bean declaration 197 */ 198 public XMLBeanDeclaration(HierarchicalConfiguration config) 199 { 200 this(config, (String) null); 201 } 202 203 /** 204 * Creates a new instance of {@code XMLBeanDeclaration} and 205 * initializes it with the configuration node that contains the bean 206 * declaration. 207 * 208 * @param config the configuration 209 * @param node the node with the bean declaration. 210 */ 211 public XMLBeanDeclaration(SubnodeConfiguration config, 212 ConfigurationNode node) 213 { 214 if (config == null) 215 { 216 throw new IllegalArgumentException( 217 "Configuration must not be null!"); 218 } 219 if (node == null) 220 { 221 throw new IllegalArgumentException("Node must not be null!"); 222 } 223 224 this.node = node; 225 configuration = config; 226 initSubnodeConfiguration(config); 227 } 228 229 /** 230 * Returns the configuration object this bean declaration is based on. 231 * 232 * @return the associated configuration 233 */ 234 public SubnodeConfiguration getConfiguration() 235 { 236 return configuration; 237 } 238 239 /** 240 * Returns the node that contains the bean declaration. 241 * 242 * @return the configuration node this bean declaration is based on 243 */ 244 public ConfigurationNode getNode() 245 { 246 return node; 247 } 248 249 /** 250 * Returns the name of the bean factory. This information is fetched from 251 * the {@code config-factory} attribute. 252 * 253 * @return the name of the bean factory 254 */ 255 public String getBeanFactoryName() 256 { 257 return getConfiguration().getString(ATTR_BEAN_FACTORY); 258 } 259 260 /** 261 * Returns a parameter for the bean factory. This information is fetched 262 * from the {@code config-factoryParam} attribute. 263 * 264 * @return the parameter for the bean factory 265 */ 266 public Object getBeanFactoryParameter() 267 { 268 return getConfiguration().getProperty(ATTR_FACTORY_PARAM); 269 } 270 271 /** 272 * Returns the name of the class of the bean to be created. This information 273 * is obtained from the {@code config-class} attribute. 274 * 275 * @return the name of the bean's class 276 */ 277 public String getBeanClassName() 278 { 279 return getConfiguration().getString(ATTR_BEAN_CLASS); 280 } 281 282 /** 283 * Returns a map with the bean's (simple) properties. The properties are 284 * collected from all attribute nodes, which are not reserved. 285 * 286 * @return a map with the bean's properties 287 */ 288 public Map<String, Object> getBeanProperties() 289 { 290 Map<String, Object> props = new HashMap<String, Object>(); 291 for (ConfigurationNode attr : getNode().getAttributes()) 292 { 293 if (!isReservedNode(attr)) 294 { 295 props.put(attr.getName(), interpolate(attr .getValue())); 296 } 297 } 298 299 return props; 300 } 301 302 /** 303 * Returns a map with bean declarations for the complex properties of the 304 * bean to be created. These declarations are obtained from the child nodes 305 * of this declaration's root node. 306 * 307 * @return a map with bean declarations for complex properties 308 */ 309 public Map<String, Object> getNestedBeanDeclarations() 310 { 311 Map<String, Object> nested = new HashMap<String, Object>(); 312 for (ConfigurationNode child : getNode().getChildren()) 313 { 314 if (!isReservedNode(child)) 315 { 316 if (nested.containsKey(child.getName())) 317 { 318 Object obj = nested.get(child.getName()); 319 List<BeanDeclaration> list; 320 if (obj instanceof List) 321 { 322 // Safe because we created the lists ourselves. 323 @SuppressWarnings("unchecked") 324 List<BeanDeclaration> tmpList = (List<BeanDeclaration>) obj; 325 list = tmpList; 326 } 327 else 328 { 329 list = new ArrayList<BeanDeclaration>(); 330 list.add((BeanDeclaration) obj); 331 nested.put(child.getName(), list); 332 } 333 list.add(createBeanDeclaration(child)); 334 } 335 else 336 { 337 nested.put(child.getName(), createBeanDeclaration(child)); 338 } 339 } 340 } 341 342 return nested; 343 } 344 345 /** 346 * Performs interpolation for the specified value. This implementation will 347 * interpolate against the current subnode configuration's parent. If sub 348 * classes need a different interpolation mechanism, they should override 349 * this method. 350 * 351 * @param value the value that is to be interpolated 352 * @return the interpolated value 353 */ 354 protected Object interpolate(Object value) 355 { 356 return PropertyConverter.interpolate(value, getConfiguration() 357 .getParent()); 358 } 359 360 /** 361 * Checks if the specified node is reserved and thus should be ignored. This 362 * method is called when the maps for the bean's properties and complex 363 * properties are collected. It checks whether the given node is an 364 * attribute node and if its name starts with the reserved prefix. 365 * 366 * @param nd the node to be checked 367 * @return a flag whether this node is reserved (and does not point to a 368 * property) 369 */ 370 protected boolean isReservedNode(ConfigurationNode nd) 371 { 372 return nd.isAttribute() 373 && (nd.getName() == null || nd.getName().startsWith( 374 RESERVED_PREFIX)); 375 } 376 377 /** 378 * Creates a new {@code BeanDeclaration} for a child node of the 379 * current configuration node. This method is called by 380 * {@code getNestedBeanDeclarations()} for all complex sub properties 381 * detected by this method. Derived classes can hook in if they need a 382 * specific initialization. This base implementation creates a 383 * {@code XMLBeanDeclaration} that is properly initialized from the 384 * passed in node. 385 * 386 * @param node the child node, for which a {@code BeanDeclaration} is 387 * to be created 388 * @return the {@code BeanDeclaration} for this child node 389 * @since 1.6 390 */ 391 protected BeanDeclaration createBeanDeclaration(ConfigurationNode node) 392 { 393 List<HierarchicalConfiguration> list = getConfiguration().configurationsAt(node.getName()); 394 if (list.size() == 1) 395 { 396 return new XMLBeanDeclaration((SubnodeConfiguration) list.get(0), node); 397 } 398 else 399 { 400 Iterator<HierarchicalConfiguration> iter = list.iterator(); 401 while (iter.hasNext()) 402 { 403 SubnodeConfiguration config = (SubnodeConfiguration) iter.next(); 404 if (config.getRootNode().equals(node)) 405 { 406 return new XMLBeanDeclaration(config, node); 407 } 408 } 409 throw new ConfigurationRuntimeException("Unable to match node for " + node.getName()); 410 } 411 } 412 413 /** 414 * Initializes the internally managed subnode configuration. This method 415 * will set some default values for some properties. 416 * 417 * @param conf the configuration to initialize 418 */ 419 private void initSubnodeConfiguration(SubnodeConfiguration conf) 420 { 421 conf.setThrowExceptionOnMissing(false); 422 conf.setExpressionEngine(null); 423 } 424 }