| 1 | /* |
| 2 | * Copyright 2006-2007 the original author or authors. |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | package org.springframework.batch.core.scope; |
| 17 | |
| 18 | import org.apache.commons.logging.Log; |
| 19 | import org.apache.commons.logging.LogFactory; |
| 20 | import org.springframework.aop.scope.ScopedProxyUtils; |
| 21 | import org.springframework.batch.core.scope.context.StepContext; |
| 22 | import org.springframework.batch.core.scope.context.StepSynchronizationManager; |
| 23 | import org.springframework.batch.core.scope.util.PlaceholderProxyFactoryBean; |
| 24 | import org.springframework.beans.BeanWrapper; |
| 25 | import org.springframework.beans.BeanWrapperImpl; |
| 26 | import org.springframework.beans.BeansException; |
| 27 | import org.springframework.beans.factory.ObjectFactory; |
| 28 | import org.springframework.beans.factory.config.BeanDefinition; |
| 29 | import org.springframework.beans.factory.config.BeanDefinitionHolder; |
| 30 | import org.springframework.beans.factory.config.BeanDefinitionVisitor; |
| 31 | import org.springframework.beans.factory.config.BeanFactoryPostProcessor; |
| 32 | import org.springframework.beans.factory.config.ConfigurableListableBeanFactory; |
| 33 | import org.springframework.beans.factory.config.Scope; |
| 34 | import org.springframework.beans.factory.support.BeanDefinitionReaderUtils; |
| 35 | import org.springframework.beans.factory.support.BeanDefinitionRegistry; |
| 36 | import org.springframework.core.Ordered; |
| 37 | import org.springframework.util.Assert; |
| 38 | import org.springframework.util.ReflectionUtils; |
| 39 | import org.springframework.util.StringValueResolver; |
| 40 | |
| 41 | /** |
| 42 | * Scope for step context. Objects in this scope use the Spring container as an |
| 43 | * object factory, so there is only one instance of such a bean per executing |
| 44 | * step. All objects in this scope are <aop:scoped-proxy/> (no need to |
| 45 | * decorate the bean definitions).<br/> |
| 46 | * <br/> |
| 47 | * |
| 48 | * In addition, support is provided for late binding of references accessible |
| 49 | * from the {@link StepContext} using #{..} placeholders. Using this feature, |
| 50 | * bean properties can be pulled from the step or job execution context and the |
| 51 | * job parameters. E.g. |
| 52 | * |
| 53 | * <pre> |
| 54 | * <bean id="..." class="..." scope="step"> |
| 55 | * <property name="parent" ref="#{stepExecutionContext[helper]}" /> |
| 56 | * </bean> |
| 57 | * |
| 58 | * <bean id="..." class="..." scope="step"> |
| 59 | * <property name="name" value="#{stepExecutionContext['input.name']}" /> |
| 60 | * </bean> |
| 61 | * |
| 62 | * <bean id="..." class="..." scope="step"> |
| 63 | * <property name="name" value="#{jobParameters[input]}" /> |
| 64 | * </bean> |
| 65 | * |
| 66 | * <bean id="..." class="..." scope="step"> |
| 67 | * <property name="name" value="#{jobExecutionContext['input.stem']}.txt" /> |
| 68 | * </bean> |
| 69 | * </pre> |
| 70 | * |
| 71 | * The {@link StepContext} is referenced using standard bean property paths (as |
| 72 | * per {@link BeanWrapper}). The examples above all show the use of the Map |
| 73 | * accessors provided as a convenience for step and job attributes. |
| 74 | * |
| 75 | * @author Dave Syer |
| 76 | * @since 2.0 |
| 77 | */ |
| 78 | public class StepScope implements Scope, BeanFactoryPostProcessor, Ordered { |
| 79 | |
| 80 | private Log logger = LogFactory.getLog(getClass()); |
| 81 | |
| 82 | private int order = Ordered.LOWEST_PRECEDENCE; |
| 83 | |
| 84 | private final Object mutex = new Object(); |
| 85 | |
| 86 | /** |
| 87 | * @param order the order value to set priority of callback execution for |
| 88 | * the {@link BeanFactoryPostProcessor} part of this scope bean. |
| 89 | */ |
| 90 | public void setOrder(int order) { |
| 91 | this.order = order; |
| 92 | } |
| 93 | |
| 94 | public int getOrder() { |
| 95 | return order; |
| 96 | } |
| 97 | |
| 98 | /** |
| 99 | * Context key for clients to use for conversation identifier. |
| 100 | */ |
| 101 | public static final String ID_KEY = "STEP_IDENTIFIER"; |
| 102 | |
| 103 | private String name = "step"; |
| 104 | |
| 105 | private boolean proxyTargetClass = false; |
| 106 | |
| 107 | private static boolean springThreeDetected; |
| 108 | |
| 109 | private static boolean cachedSpringThreeResult; |
| 110 | |
| 111 | /** |
| 112 | * Flag to indicate that proxies should use dynamic subclassing. This allows |
| 113 | * classes with no interface to be proxied. Defaults to false. |
| 114 | * |
| 115 | * @param proxyTargetClass set to true to have proxies created using dynamic |
| 116 | * subclasses |
| 117 | */ |
| 118 | public void setProxyTargetClass(boolean proxyTargetClass) { |
| 119 | this.proxyTargetClass = proxyTargetClass; |
| 120 | } |
| 121 | |
| 122 | /** |
| 123 | * If Spring 3.0 is available, this will be used to resolve expressions in |
| 124 | * step-scoped beans. This method is part of the Scope SPI in Spring 3.0, |
| 125 | * but should just be ignored by earlier versions of Spring. |
| 126 | */ |
| 127 | public Object resolveContextualObject(String key) { |
| 128 | StepContext context = getContext(); |
| 129 | // TODO: support for attributes as well maybe (setters not exposed yet |
| 130 | // so not urgent). |
| 131 | return new BeanWrapperImpl(context).getPropertyValue(key); |
| 132 | } |
| 133 | |
| 134 | /** |
| 135 | * @see Scope#get(String, ObjectFactory) |
| 136 | */ |
| 137 | public Object get(String name, ObjectFactory objectFactory) { |
| 138 | |
| 139 | StepContext context = getContext(); |
| 140 | Object scopedObject = context.getAttribute(name); |
| 141 | |
| 142 | if (scopedObject == null) { |
| 143 | |
| 144 | synchronized (mutex) { |
| 145 | scopedObject = context.getAttribute(name); |
| 146 | if (scopedObject == null) { |
| 147 | |
| 148 | logger.debug(String.format("Creating object in scope=%s, name=%s", this.name, name)); |
| 149 | |
| 150 | scopedObject = objectFactory.getObject(); |
| 151 | context.setAttribute(name, scopedObject); |
| 152 | |
| 153 | } |
| 154 | |
| 155 | } |
| 156 | |
| 157 | } |
| 158 | return scopedObject; |
| 159 | } |
| 160 | |
| 161 | /** |
| 162 | * @see Scope#getConversationId() |
| 163 | */ |
| 164 | public String getConversationId() { |
| 165 | StepContext context = getContext(); |
| 166 | return context.getId(); |
| 167 | } |
| 168 | |
| 169 | /** |
| 170 | * @see Scope#registerDestructionCallback(String, Runnable) |
| 171 | */ |
| 172 | public void registerDestructionCallback(String name, Runnable callback) { |
| 173 | StepContext context = getContext(); |
| 174 | logger.debug(String.format("Registered destruction callback in scope=%s, name=%s", this.name, name)); |
| 175 | context.registerDestructionCallback(name, callback); |
| 176 | } |
| 177 | |
| 178 | /** |
| 179 | * @see Scope#remove(String) |
| 180 | */ |
| 181 | public Object remove(String name) { |
| 182 | StepContext context = getContext(); |
| 183 | logger.debug(String.format("Removing from scope=%s, name=%s", this.name, name)); |
| 184 | return context.removeAttribute(name); |
| 185 | } |
| 186 | |
| 187 | /** |
| 188 | * Get an attribute accessor in the form of a {@link StepContext} that can |
| 189 | * be used to store scoped bean instances. |
| 190 | * |
| 191 | * @return the current step context which we can use as a scope storage |
| 192 | * medium |
| 193 | */ |
| 194 | private StepContext getContext() { |
| 195 | StepContext context = StepSynchronizationManager.getContext(); |
| 196 | if (context == null) { |
| 197 | throw new IllegalStateException("No context holder available for step scope"); |
| 198 | } |
| 199 | return context; |
| 200 | } |
| 201 | |
| 202 | /** |
| 203 | * Register this scope with the enclosing BeanFactory. |
| 204 | * |
| 205 | * @see BeanFactoryPostProcessor#postProcessBeanFactory(ConfigurableListableBeanFactory) |
| 206 | * |
| 207 | * @param beanFactory the BeanFactory to register with |
| 208 | * @throws BeansException if there is a problem. |
| 209 | */ |
| 210 | public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException { |
| 211 | |
| 212 | beanFactory.registerScope(name, this); |
| 213 | |
| 214 | Assert.state(beanFactory instanceof BeanDefinitionRegistry, |
| 215 | "BeanFactory was not a BeanDefinitionRegistry, so StepScope cannot be used."); |
| 216 | BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory; |
| 217 | |
| 218 | for (String beanName : beanFactory.getBeanDefinitionNames()) { |
| 219 | BeanDefinition definition = beanFactory.getBeanDefinition(beanName); |
| 220 | // Replace this or any of its inner beans with scoped proxy if it |
| 221 | // has this scope |
| 222 | boolean scoped = name.equals(definition.getScope()); |
| 223 | Scopifier scopifier = new Scopifier(registry, name, proxyTargetClass, scoped); |
| 224 | scopifier.visitBeanDefinition(definition); |
| 225 | if (scoped) { |
| 226 | if (!isSpringThree()) { |
| 227 | new ExpressionHider(name, scoped).visitBeanDefinition(definition); |
| 228 | } |
| 229 | createScopedProxy(beanName, definition, registry, proxyTargetClass); |
| 230 | } |
| 231 | } |
| 232 | |
| 233 | } |
| 234 | |
| 235 | private static boolean isSpringThree() { |
| 236 | if (!cachedSpringThreeResult) { |
| 237 | springThreeDetected = ReflectionUtils.findMethod(Scope.class, "resolveContextualObject", |
| 238 | new Class<?>[] { String.class }) != null; |
| 239 | cachedSpringThreeResult = true; |
| 240 | } |
| 241 | return springThreeDetected; |
| 242 | } |
| 243 | |
| 244 | /** |
| 245 | * Public setter for the name property. This can then be used as a bean |
| 246 | * definition attribute, e.g. scope="step". Defaults to "step". |
| 247 | * |
| 248 | * @param name the name to set for this scope. |
| 249 | */ |
| 250 | public void setName(String name) { |
| 251 | this.name = name; |
| 252 | } |
| 253 | |
| 254 | /** |
| 255 | * Wrap a target bean definition in a proxy that defers initialization until |
| 256 | * after the {@link StepContext} is available. Amounts to adding |
| 257 | * <aop-auto-proxy/> to a step scoped bean. Also if Spring EL is not |
| 258 | * available will enable a weak version of late binding as described in the |
| 259 | * class-level docs. |
| 260 | * |
| 261 | * @param beanName the bean name to replace |
| 262 | * @param definition the bean definition to replace |
| 263 | * @param registry the enclosing {@link BeanDefinitionRegistry} |
| 264 | * @param proxyTargetClass true if we need to force use of dynamic |
| 265 | * subclasses |
| 266 | * @return a {@link BeanDefinitionHolder} for the new representation of the |
| 267 | * target. Caller should register it if needed to be visible at top level in |
| 268 | * bean factory. |
| 269 | */ |
| 270 | private static BeanDefinitionHolder createScopedProxy(String beanName, BeanDefinition definition, |
| 271 | BeanDefinitionRegistry registry, boolean proxyTargetClass) { |
| 272 | |
| 273 | BeanDefinitionHolder proxyHolder; |
| 274 | |
| 275 | if (isSpringThree()) { |
| 276 | proxyHolder = ScopedProxyUtils.createScopedProxy(new BeanDefinitionHolder(definition, beanName), registry, |
| 277 | proxyTargetClass); |
| 278 | } |
| 279 | else { |
| 280 | // Create the scoped proxy... |
| 281 | proxyHolder = PlaceholderProxyFactoryBean.createScopedProxy(new BeanDefinitionHolder(definition, beanName), |
| 282 | registry, proxyTargetClass); |
| 283 | // ...and register it under the original target name |
| 284 | } |
| 285 | registry.registerBeanDefinition(beanName, proxyHolder.getBeanDefinition()); |
| 286 | |
| 287 | return proxyHolder; |
| 288 | |
| 289 | } |
| 290 | |
| 291 | /** |
| 292 | * Helper class to scan a bean definition hierarchy and force the use of |
| 293 | * auto-proxy for step scoped beans. |
| 294 | * |
| 295 | * @author Dave Syer |
| 296 | * |
| 297 | */ |
| 298 | private static class Scopifier extends BeanDefinitionVisitor { |
| 299 | |
| 300 | private final boolean proxyTargetClass; |
| 301 | |
| 302 | private final BeanDefinitionRegistry registry; |
| 303 | |
| 304 | private final String scope; |
| 305 | |
| 306 | private final boolean scoped; |
| 307 | |
| 308 | public Scopifier(BeanDefinitionRegistry registry, String scope, boolean proxyTargetClass, boolean scoped) { |
| 309 | super(new StringValueResolver() { |
| 310 | public String resolveStringValue(String value) { |
| 311 | return value; |
| 312 | } |
| 313 | }); |
| 314 | this.registry = registry; |
| 315 | this.proxyTargetClass = proxyTargetClass; |
| 316 | this.scope = scope; |
| 317 | this.scoped = scoped; |
| 318 | } |
| 319 | |
| 320 | @Override |
| 321 | protected Object resolveValue(Object value) { |
| 322 | |
| 323 | BeanDefinition definition = null; |
| 324 | String beanName = null; |
| 325 | if (value instanceof BeanDefinition) { |
| 326 | definition = (BeanDefinition) value; |
| 327 | beanName = BeanDefinitionReaderUtils.generateBeanName(definition, registry); |
| 328 | } |
| 329 | else if (value instanceof BeanDefinitionHolder) { |
| 330 | BeanDefinitionHolder holder = (BeanDefinitionHolder) value; |
| 331 | definition = holder.getBeanDefinition(); |
| 332 | beanName = holder.getBeanName(); |
| 333 | } |
| 334 | |
| 335 | if (definition != null) { |
| 336 | boolean nestedScoped = scope.equals(definition.getScope()); |
| 337 | boolean scopeChangeRequiresProxy = !scoped && nestedScoped; |
| 338 | if (!isSpringThree()) { |
| 339 | new ExpressionHider(scope, nestedScoped).visitBeanDefinition(definition); |
| 340 | } |
| 341 | if (scopeChangeRequiresProxy) { |
| 342 | // Exit here so that nested inner bean definitions are not |
| 343 | // analysed |
| 344 | return createScopedProxy(beanName, definition, registry, proxyTargetClass); |
| 345 | } |
| 346 | } |
| 347 | |
| 348 | // Nested inner bean definitions are recursively analysed here |
| 349 | value = super.resolveValue(value); |
| 350 | return value; |
| 351 | |
| 352 | } |
| 353 | |
| 354 | } |
| 355 | |
| 356 | /** |
| 357 | * Helper class to scan a bean definition hierarchy and hide placeholders |
| 358 | * from Spring EL. |
| 359 | * |
| 360 | * @author Dave Syer |
| 361 | * |
| 362 | */ |
| 363 | private static class ExpressionHider extends BeanDefinitionVisitor { |
| 364 | |
| 365 | private static final String PLACEHOLDER_PREFIX = "#{"; |
| 366 | |
| 367 | private static final String PLACEHOLDER_SUFFIX = "}"; |
| 368 | |
| 369 | private static final String REPLACEMENT_PREFIX = "%{"; |
| 370 | |
| 371 | private final String scope; |
| 372 | |
| 373 | private final boolean scoped; |
| 374 | |
| 375 | private ExpressionHider(String scope, final boolean scoped) { |
| 376 | super(new StringValueResolver() { |
| 377 | public String resolveStringValue(String value) { |
| 378 | if (scoped && value.contains(PLACEHOLDER_PREFIX) && value.contains(PLACEHOLDER_SUFFIX)) { |
| 379 | value = value.replace(PLACEHOLDER_PREFIX, REPLACEMENT_PREFIX); |
| 380 | } |
| 381 | return value; |
| 382 | } |
| 383 | }); |
| 384 | this.scope = scope; |
| 385 | this.scoped = scoped; |
| 386 | } |
| 387 | |
| 388 | @Override |
| 389 | protected Object resolveValue(Object value) { |
| 390 | BeanDefinition definition = null; |
| 391 | if (value instanceof BeanDefinition) { |
| 392 | definition = (BeanDefinition) value; |
| 393 | } |
| 394 | else if (value instanceof BeanDefinitionHolder) { |
| 395 | BeanDefinitionHolder holder = (BeanDefinitionHolder) value; |
| 396 | definition = holder.getBeanDefinition(); |
| 397 | } |
| 398 | if (definition != null) { |
| 399 | String otherScope = definition.getScope(); |
| 400 | boolean scopeChange = !scope.equals(otherScope); |
| 401 | if (scopeChange) { |
| 402 | new ExpressionHider(otherScope == null ? scope : otherScope, !scoped) |
| 403 | .visitBeanDefinition(definition); |
| 404 | // Exit here so that nested inner bean definitions are not |
| 405 | // analysed by both visitors |
| 406 | return value; |
| 407 | } |
| 408 | } |
| 409 | // Nested inner bean definitions are recursively analysed here |
| 410 | value = super.resolveValue(value); |
| 411 | return value; |
| 412 | } |
| 413 | |
| 414 | } |
| 415 | |
| 416 | } |