| 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.util; |
| 17 | |
| 18 | import java.beans.PropertyEditor; |
| 19 | import java.util.Date; |
| 20 | |
| 21 | import org.springframework.aop.TargetSource; |
| 22 | import org.springframework.aop.target.SimpleBeanTargetSource; |
| 23 | import org.springframework.beans.BeanWrapper; |
| 24 | import org.springframework.beans.BeanWrapperImpl; |
| 25 | import org.springframework.beans.BeansException; |
| 26 | import org.springframework.beans.PropertyEditorRegistrySupport; |
| 27 | import org.springframework.beans.TypeConverter; |
| 28 | import org.springframework.beans.TypeMismatchException; |
| 29 | import org.springframework.beans.factory.InitializingBean; |
| 30 | import org.springframework.beans.factory.config.BeanDefinitionVisitor; |
| 31 | import org.springframework.beans.factory.config.TypedStringValue; |
| 32 | import org.springframework.beans.factory.support.DefaultListableBeanFactory; |
| 33 | import org.springframework.beans.factory.support.GenericBeanDefinition; |
| 34 | import org.springframework.core.AttributeAccessor; |
| 35 | import org.springframework.core.MethodParameter; |
| 36 | import org.springframework.util.Assert; |
| 37 | import org.springframework.util.StringValueResolver; |
| 38 | |
| 39 | /** |
| 40 | * A {@link TargetSource} that lazily initializes its target, replacing bean |
| 41 | * definition properties dynamically if they are marked as placeholders. String |
| 42 | * values with embedded <code>%{key}</code> patterns will be replaced with the |
| 43 | * corresponding value from the injected context (which must also be a String). |
| 44 | * This includes dynamically locating a bean reference (e.g. |
| 45 | * <code>ref="%{foo}"</code>), and partial replacement of patterns (e.g. |
| 46 | * <code>value="%{foo}-bar-%{spam}"</code>). These replacements work for context |
| 47 | * values that are primitive (String, Long, Integer). You can also replace |
| 48 | * non-primitive values directly by making the whole bean property value into a |
| 49 | * placeholder (e.g. <code>value="%{foo}"</code> where <code>foo</code> is a |
| 50 | * property in the context). |
| 51 | * |
| 52 | * @author Dave Syer |
| 53 | * |
| 54 | */ |
| 55 | public class PlaceholderTargetSource extends SimpleBeanTargetSource implements InitializingBean { |
| 56 | |
| 57 | /** |
| 58 | * Key for placeholders to be replaced from the properties provided. |
| 59 | */ |
| 60 | private static final String PLACEHOLDER_PREFIX = "%{"; |
| 61 | |
| 62 | private static final String PLACEHOLDER_SUFFIX = "}"; |
| 63 | |
| 64 | private ContextFactory contextFactory; |
| 65 | |
| 66 | private String beanName; |
| 67 | |
| 68 | /** |
| 69 | * Public setter for the context factory. Used to construct the context root |
| 70 | * whenever placeholders are replaced in a bean definition. |
| 71 | * |
| 72 | * @param contextFactory the {@link ContextFactory} |
| 73 | */ |
| 74 | public void setContextFactory(ContextFactory contextFactory) { |
| 75 | this.contextFactory = contextFactory; |
| 76 | } |
| 77 | |
| 78 | /* |
| 79 | * (non-Javadoc) |
| 80 | * |
| 81 | * @see |
| 82 | * org.springframework.beans.factory.InitializingBean#afterPropertiesSet() |
| 83 | */ |
| 84 | public void afterPropertiesSet() { |
| 85 | Assert.notNull(contextFactory, "The ContextFactory must be set."); |
| 86 | beanName = getTargetBeanName() + "#" + contextFactory.getContextId(); |
| 87 | } |
| 88 | |
| 89 | /* |
| 90 | * (non-Javadoc) |
| 91 | * |
| 92 | * @see org.springframework.aop.target.LazyInitTargetSource#getTarget() |
| 93 | */ |
| 94 | @Override |
| 95 | public synchronized Object getTarget() throws BeansException { |
| 96 | |
| 97 | // Object target; |
| 98 | Object target = getTargetFromContext(); |
| 99 | if (target != null) { |
| 100 | return target; |
| 101 | } |
| 102 | |
| 103 | DefaultListableBeanFactory listableBeanFactory = (DefaultListableBeanFactory) getBeanFactory(); |
| 104 | |
| 105 | final TypeConverter typeConverter = listableBeanFactory.getTypeConverter(); |
| 106 | |
| 107 | DefaultListableBeanFactory beanFactory = new DefaultListableBeanFactory(listableBeanFactory); |
| 108 | beanFactory.copyConfigurationFrom(listableBeanFactory); |
| 109 | |
| 110 | final TypeConverter contextTypeConverter = new TypeConverter() { |
| 111 | @SuppressWarnings("unchecked") |
| 112 | public Object convertIfNecessary(Object value, Class requiredType, MethodParameter methodParam) |
| 113 | throws TypeMismatchException { |
| 114 | Object result = null; |
| 115 | if (value instanceof String) { |
| 116 | String key = (String) value; |
| 117 | if (key.startsWith(PLACEHOLDER_PREFIX) && key.endsWith(PLACEHOLDER_SUFFIX)) { |
| 118 | key = extractKey(key); |
| 119 | result = convertFromContext(key, requiredType); |
| 120 | if (result == null) { |
| 121 | Object property = getPropertyFromContext(key); |
| 122 | // Give the normal type converter a chance by |
| 123 | // reversing to a String |
| 124 | if (property != null) { |
| 125 | property = convertToString(property, typeConverter); |
| 126 | if (property != null) { |
| 127 | value = property; |
| 128 | } |
| 129 | logger.debug(String.format("Bound %%{%s} to String value [%s]", key, result)); |
| 130 | } |
| 131 | else { |
| 132 | throw new IllegalStateException("Cannot bind to placeholder: " + key); |
| 133 | } |
| 134 | } |
| 135 | else { |
| 136 | logger.debug(String.format("Bound %%{%s} to [%s]", key, result)); |
| 137 | } |
| 138 | } |
| 139 | } |
| 140 | else if (requiredType.isAssignableFrom(value.getClass())) { |
| 141 | result = value; |
| 142 | } |
| 143 | else if (requiredType.isAssignableFrom(String.class)) { |
| 144 | result = convertToString(value, typeConverter); |
| 145 | if (result == null) { |
| 146 | logger.debug("Falling back on toString for conversion of : [" + value.getClass() + "]"); |
| 147 | result = value.toString(); |
| 148 | } |
| 149 | } |
| 150 | return result != null ? result : typeConverter.convertIfNecessary(value, requiredType, methodParam); |
| 151 | } |
| 152 | |
| 153 | @SuppressWarnings("unchecked") |
| 154 | public Object convertIfNecessary(Object value, Class requiredType) throws TypeMismatchException { |
| 155 | return convertIfNecessary(value, requiredType, null); |
| 156 | } |
| 157 | }; |
| 158 | beanFactory.setTypeConverter(contextTypeConverter); |
| 159 | |
| 160 | try { |
| 161 | |
| 162 | /* |
| 163 | * Need to use the merged bean definition here, otherwise it gets |
| 164 | * cached and "frozen" in and the "regular" bean definition does not |
| 165 | * come back when getBean() is called later on |
| 166 | */ |
| 167 | String targetBeanName = getTargetBeanName(); |
| 168 | GenericBeanDefinition beanDefinition = new GenericBeanDefinition(listableBeanFactory |
| 169 | .getMergedBeanDefinition(targetBeanName)); |
| 170 | logger.debug("Rehydrating scoped target: [" + targetBeanName + "]"); |
| 171 | |
| 172 | BeanDefinitionVisitor visitor = new PlaceholderBeanDefinitionVisitor(contextTypeConverter); |
| 173 | |
| 174 | beanFactory.registerBeanDefinition(beanName, beanDefinition); |
| 175 | // Make the replacements before the target is hydrated |
| 176 | visitor.visitBeanDefinition(beanDefinition); |
| 177 | target = beanFactory.getBean(beanName); |
| 178 | putTargetInContext(target); |
| 179 | return target; |
| 180 | |
| 181 | } |
| 182 | finally { |
| 183 | beanFactory.removeBeanDefinition(beanName); |
| 184 | beanFactory = null; |
| 185 | // Anything else we can do to clean it up? |
| 186 | } |
| 187 | |
| 188 | } |
| 189 | |
| 190 | private void putTargetInContext(Object target) { |
| 191 | Object context = contextFactory.getContext(); |
| 192 | if (context instanceof AttributeAccessor) { |
| 193 | ((AttributeAccessor) context).setAttribute(beanName, target); |
| 194 | } |
| 195 | } |
| 196 | |
| 197 | private Object getTargetFromContext() { |
| 198 | Object context = contextFactory.getContext(); |
| 199 | if (context instanceof AttributeAccessor) { |
| 200 | return ((AttributeAccessor) context).getAttribute(beanName); |
| 201 | } |
| 202 | return null; |
| 203 | } |
| 204 | |
| 205 | /** |
| 206 | * @param value |
| 207 | * @param typeConverter |
| 208 | * @return a String representation of the input if possible |
| 209 | */ |
| 210 | protected String convertToString(Object value, TypeConverter typeConverter) { |
| 211 | String result = null; |
| 212 | try { |
| 213 | // Give it one chance to convert - this forces the default editors |
| 214 | // to be registered |
| 215 | result = (String) typeConverter.convertIfNecessary(value, String.class); |
| 216 | } |
| 217 | catch (TypeMismatchException e) { |
| 218 | // ignore |
| 219 | } |
| 220 | if (result == null && typeConverter instanceof PropertyEditorRegistrySupport) { |
| 221 | /* |
| 222 | * PropertyEditorRegistrySupport is de rigeur with TypeConverter |
| 223 | * instances used internally by Spring. If we have one of those then |
| 224 | * we can convert to String but the TypeConverter doesn't know how |
| 225 | * to. |
| 226 | */ |
| 227 | PropertyEditorRegistrySupport registry = (PropertyEditorRegistrySupport) typeConverter; |
| 228 | PropertyEditor editor = registry.findCustomEditor(value.getClass(), null); |
| 229 | if (editor != null) { |
| 230 | if (registry.isSharedEditor(editor)) { |
| 231 | // Synchronized access to shared editor |
| 232 | // instance. |
| 233 | synchronized (editor) { |
| 234 | editor.setValue(value); |
| 235 | result = editor.getAsText(); |
| 236 | } |
| 237 | } |
| 238 | else { |
| 239 | editor.setValue(value); |
| 240 | result = editor.getAsText(); |
| 241 | } |
| 242 | } |
| 243 | } |
| 244 | return result; |
| 245 | } |
| 246 | |
| 247 | /** |
| 248 | * @param value |
| 249 | * @param requiredType |
| 250 | * @return |
| 251 | */ |
| 252 | private Object convertFromContext(String key, Class<?> requiredType) { |
| 253 | Object result = null; |
| 254 | Object property = getPropertyFromContext(key); |
| 255 | if (property == null || requiredType.isAssignableFrom(property.getClass())) { |
| 256 | result = property; |
| 257 | } |
| 258 | return result; |
| 259 | } |
| 260 | |
| 261 | private Object getPropertyFromContext(String key) { |
| 262 | BeanWrapper wrapper = new BeanWrapperImpl(contextFactory.getContext()); |
| 263 | if (wrapper.isReadableProperty(key)) { |
| 264 | return wrapper.getPropertyValue(key); |
| 265 | } |
| 266 | return null; |
| 267 | } |
| 268 | |
| 269 | private String extractKey(String value) { |
| 270 | return value.substring(value.indexOf(PLACEHOLDER_PREFIX) + PLACEHOLDER_PREFIX.length(), value |
| 271 | .indexOf(PLACEHOLDER_SUFFIX)); |
| 272 | } |
| 273 | |
| 274 | /** |
| 275 | * Determine whether the input is a whole key in the form |
| 276 | * <code>%{...}</code>, i.e. starting with the correct prefix, ending with |
| 277 | * the correct suffix and containing only one of each. |
| 278 | * |
| 279 | * @param value a String with placeholder patterns |
| 280 | * @return true if the value is a key |
| 281 | */ |
| 282 | private boolean isKey(String value) { |
| 283 | return value.indexOf(PLACEHOLDER_PREFIX) == value.lastIndexOf(PLACEHOLDER_PREFIX) |
| 284 | && value.startsWith(PLACEHOLDER_PREFIX) && value.endsWith(PLACEHOLDER_SUFFIX); |
| 285 | } |
| 286 | |
| 287 | /** |
| 288 | * A {@link BeanDefinitionVisitor} that will replace embedded placeholders |
| 289 | * with values from the provided context. |
| 290 | * |
| 291 | * @author Dave Syer |
| 292 | * |
| 293 | */ |
| 294 | private final class PlaceholderBeanDefinitionVisitor extends BeanDefinitionVisitor { |
| 295 | |
| 296 | public PlaceholderBeanDefinitionVisitor(final TypeConverter typeConverter) { |
| 297 | super(new PlaceholderStringValueResolver(typeConverter)); |
| 298 | } |
| 299 | |
| 300 | protected Object resolveValue(Object value) { |
| 301 | |
| 302 | if (value instanceof TypedStringValue) { |
| 303 | |
| 304 | TypedStringValue typedStringValue = (TypedStringValue) value; |
| 305 | String stringValue = typedStringValue.getValue(); |
| 306 | if (stringValue != null) { |
| 307 | |
| 308 | // If the value is a whole key, try to simply replace it from context. |
| 309 | if (isKey(stringValue)) { |
| 310 | String key = extractKey(stringValue); |
| 311 | Object result = getPropertyFromContext(key); |
| 312 | if (result != null) { |
| 313 | value = result; |
| 314 | logger.debug(String.format("Bound %%{%s} to obtain [%s]", key, result)); |
| 315 | } |
| 316 | } |
| 317 | else { |
| 318 | // Otherwise it might contain embedded keys so we try to replace those |
| 319 | String visitedString = resolveStringValue(stringValue); |
| 320 | typedStringValue.setValue(visitedString); |
| 321 | } |
| 322 | } |
| 323 | |
| 324 | } |
| 325 | else { |
| 326 | |
| 327 | value = super.resolveValue(value); |
| 328 | |
| 329 | } |
| 330 | |
| 331 | return value; |
| 332 | |
| 333 | } |
| 334 | |
| 335 | } |
| 336 | |
| 337 | private final class PlaceholderStringValueResolver implements StringValueResolver { |
| 338 | |
| 339 | private final TypeConverter typeConverter; |
| 340 | |
| 341 | private PlaceholderStringValueResolver(TypeConverter typeConverter) { |
| 342 | this.typeConverter = typeConverter; |
| 343 | } |
| 344 | |
| 345 | public String resolveStringValue(String strVal) { |
| 346 | if (!strVal.contains(PLACEHOLDER_PREFIX)) { |
| 347 | return strVal; |
| 348 | } |
| 349 | return replacePlaceholders(strVal, typeConverter); |
| 350 | } |
| 351 | |
| 352 | /** |
| 353 | * Convenience method to replace all the placeholders in the input. |
| 354 | * |
| 355 | * @param typeConverter a {@link TypeConverter} that can be used to |
| 356 | * convert placeholder keys to context values |
| 357 | * @param value the value to replace placeholders in |
| 358 | * @return the input with placeholders replaced |
| 359 | */ |
| 360 | private String replacePlaceholders(String value, TypeConverter typeConverter) { |
| 361 | |
| 362 | StringBuilder result = new StringBuilder(value); |
| 363 | |
| 364 | int first = result.indexOf(PLACEHOLDER_PREFIX); |
| 365 | int next = result.indexOf(PLACEHOLDER_SUFFIX, first + 1); |
| 366 | |
| 367 | while (first >= 0) { |
| 368 | |
| 369 | Assert.state(next > 0, String.format("Placeholder key incorrectly specified: use %skey%s (in %s)", |
| 370 | PLACEHOLDER_PREFIX, PLACEHOLDER_SUFFIX, value)); |
| 371 | |
| 372 | String key = result.substring(first + PLACEHOLDER_PREFIX.length(), next); |
| 373 | |
| 374 | boolean replaced = replaceIfTypeMatches(result, first, next, key, String.class, typeConverter); |
| 375 | replaced |= replaceIfTypeMatches(result, first, next, key, Long.class, typeConverter); |
| 376 | replaced |= replaceIfTypeMatches(result, first, next, key, Integer.class, typeConverter); |
| 377 | replaced |= replaceIfTypeMatches(result, first, next, key, Date.class, typeConverter); |
| 378 | if (!replaced) { |
| 379 | if (!value.startsWith(PLACEHOLDER_PREFIX) || !value.endsWith(PLACEHOLDER_SUFFIX)) { |
| 380 | throw new IllegalStateException(String.format("Cannot bind to partial key %%{%s} in %s", key, |
| 381 | value)); |
| 382 | } |
| 383 | logger.debug(String.format("Deferring binding of placeholder: %%{%s}", key)); |
| 384 | } |
| 385 | else { |
| 386 | logger.debug(String.format("Bound %%{%s} to obtain [%s]", key, result)); |
| 387 | } |
| 388 | first = result.indexOf(PLACEHOLDER_PREFIX, first + 1); |
| 389 | next = result.indexOf(PLACEHOLDER_SUFFIX, first + 1); |
| 390 | |
| 391 | } |
| 392 | |
| 393 | return result.toString(); |
| 394 | |
| 395 | } |
| 396 | |
| 397 | private boolean replaceIfTypeMatches(StringBuilder result, int first, int next, String key, |
| 398 | Class<?> requiredType, TypeConverter typeConverter) { |
| 399 | Object property = convertFromContext(key, requiredType); |
| 400 | if (property != null) { |
| 401 | result.replace(first, next + 1, (String) typeConverter.convertIfNecessary(property, String.class)); |
| 402 | return true; |
| 403 | } |
| 404 | return false; |
| 405 | } |
| 406 | |
| 407 | } |
| 408 | |
| 409 | } |