| 1 | package com.hammurapi.convert; |
| 2 | |
| 3 | import java.lang.reflect.InvocationTargetException; |
| 4 | import java.lang.reflect.Method; |
| 5 | import java.util.ArrayList; |
| 6 | import java.util.Collection; |
| 7 | import java.util.Collections; |
| 8 | import java.util.HashMap; |
| 9 | import java.util.HashSet; |
| 10 | import java.util.List; |
| 11 | import java.util.Map; |
| 12 | import java.util.ServiceLoader; |
| 13 | import java.util.Set; |
| 14 | |
| 15 | import com.hammurapi.common.Adaptable; |
| 16 | import com.hammurapi.common.Context; |
| 17 | |
| 18 | public class ConvertingService { |
| 19 | |
| 20 | private interface ConvertersBucket<S, T> { |
| 21 | |
| 22 | T convert(S source, Context context); |
| 23 | } |
| 24 | |
| 25 | /** |
| 26 | * Converter which delegates to convert() method. |
| 27 | */ |
| 28 | public static final Converter CONVERTER = new Converter() { |
| 29 | |
| 30 | @SuppressWarnings("unchecked") |
| 31 | public Object convert(Object source, Class targetType, Context context) throws ConversionException { |
| 32 | return ConvertingService.convert(source, targetType, context); |
| 33 | } |
| 34 | |
| 35 | }; |
| 36 | |
| 37 | /** |
| 38 | * Converts source to target type using Java 6 service loading for AtomicConverterBundle, AtomicConverter, and Converter services |
| 39 | * If no converter is found, this method performs converter discovery through |
| 40 | * constructors if target type is a class and through duck conversion if target |
| 41 | * type is an interface. |
| 42 | * Invocation of this method is equivalent to invocation of |
| 43 | * <code>convert(source, targetType, false)</code> |
| 44 | * @param source Source object. |
| 45 | * @param targetType Target type. |
| 46 | * @return Source object converted to target type or null if no converter |
| 47 | * is available for source/targetType combination |
| 48 | * @throws ConversionException |
| 49 | */ |
| 50 | public static <S, T> T convert(S source, Class<T> targetType) throws ConversionException { |
| 51 | return convert(source, targetType, null, false, null); |
| 52 | } |
| 53 | |
| 54 | /** |
| 55 | * Converts source to target type using Java 6 service loading for AtomicConverterBundle, AtomicConverter, and Converter services |
| 56 | * If no converter is found, this method performs converter discovery through |
| 57 | * constructors if target type is a class and through duck conversion if target |
| 58 | * type is an interface. |
| 59 | * Invocation of this method is equivalent to invocation of |
| 60 | * <code>convert(source, targetType, false)</code> |
| 61 | * @param source Source object. |
| 62 | * @param targetType Target type. |
| 63 | * @param context Conversion context. |
| 64 | * @return Source object converted to target type or null if no converter |
| 65 | * is available for source/targetType combination |
| 66 | * @throws ConversionException |
| 67 | */ |
| 68 | public static <S, T> T convert(S source, Class<T> targetType, Context context) throws ConversionException { |
| 69 | return convert(source, targetType, context, false, null); |
| 70 | } |
| 71 | |
| 72 | /** |
| 73 | * Converts source to target type using Java 6 service loading for AtomicConverterBundle, AtomicConverter, and Converter services |
| 74 | * If no converter is found, this method performs converter discovery through |
| 75 | * constructors if target type is a class and through duck conversion if target |
| 76 | * type is an interface. |
| 77 | * Invocation of this method is equivalent to invocation of |
| 78 | * <code>convert(source, targetType, false)</code> |
| 79 | * @param source Source object. |
| 80 | * @param targetType Target type. |
| 81 | * @param classLoader Class loader, source of converters. |
| 82 | * @return Source object converted to target type or null if no converter |
| 83 | * is available for source/targetType combination |
| 84 | * @throws ConversionException |
| 85 | */ |
| 86 | public static <S, T> T convert(S source, Class<T> targetType, ClassLoader classLoader) throws ConversionException { |
| 87 | return convert(source, targetType, null, false, classLoader); |
| 88 | } |
| 89 | |
| 90 | private static class ConverterKey<S,T> { |
| 91 | Class<S> sourceType; |
| 92 | Class<T> targetType; |
| 93 | |
| 94 | public ConverterKey(Class<S> sourceType, Class<T> targetType) { |
| 95 | super(); |
| 96 | this.sourceType = sourceType; |
| 97 | this.targetType = targetType; |
| 98 | } |
| 99 | |
| 100 | public int hashCode() { |
| 101 | final int prime = 31; |
| 102 | int result = 1; |
| 103 | result = prime * result + ((sourceType == null) ? 0 : sourceType.hashCode()); |
| 104 | result = prime * result + ((targetType == null) ? 0 : targetType.hashCode()); |
| 105 | return result; |
| 106 | } |
| 107 | |
| 108 | @SuppressWarnings("unchecked") |
| 109 | public boolean equals(Object obj) { |
| 110 | return |
| 111 | sourceType == ((ConverterKey<S, T>) obj).sourceType |
| 112 | && targetType == ((ConverterKey<S, T>) obj).targetType; |
| 113 | } |
| 114 | |
| 115 | } |
| 116 | |
| 117 | private static class ClassLoaderConvertersEntry { |
| 118 | private static final String CONVERT = "convert"; |
| 119 | |
| 120 | private ClassLoader classLoader; |
| 121 | |
| 122 | public ClassLoaderConvertersEntry(ClassLoader classLoader) { |
| 123 | this.classLoader = classLoader; |
| 124 | } |
| 125 | |
| 126 | private Converter master = new Converter() { |
| 127 | |
| 128 | @SuppressWarnings("unchecked") |
| 129 | public Object convert(Object source, Class targetType, Context context) throws ConversionException { |
| 130 | if (source==null) { |
| 131 | return null; |
| 132 | } |
| 133 | |
| 134 | if (targetType.isInstance(source)) { |
| 135 | return source; |
| 136 | } |
| 137 | |
| 138 | final ConvertersBucket<Object, Object> bucket = findConverter(source.getClass(), targetType); |
| 139 | if (bucket!=null) { |
| 140 | Object ret = bucket.convert(source, context); |
| 141 | if (ret!=null) { |
| 142 | return ret; |
| 143 | } |
| 144 | } |
| 145 | |
| 146 | for (ConverterPart part: parts) { |
| 147 | Object ret = part.convert(source, targetType, context, this); |
| 148 | if (ret!=null) { |
| 149 | return ret; |
| 150 | } |
| 151 | } |
| 152 | |
| 153 | for (Converter subConverter: subConverters) { |
| 154 | Object ret = subConverter.convert(source, targetType, context); |
| 155 | if (ret!=null) { |
| 156 | return ret; |
| 157 | } |
| 158 | } |
| 159 | |
| 160 | return null; |
| 161 | } |
| 162 | |
| 163 | }; |
| 164 | |
| 165 | // private Converter<?,?> chainingMaster = new Converter<?,?>() { |
| 166 | // |
| 167 | // public Object convert(Object source, Class targetType, Context context) throws ConversionException { |
| 168 | // if (source==null) { |
| 169 | // return null; |
| 170 | // } |
| 171 | // |
| 172 | // if (targetType.isInstance(source)) { |
| 173 | // return source; |
| 174 | // } |
| 175 | // |
| 176 | // ConvertersBucket bucket = findChainingConverter(source.getClass(), targetType); |
| 177 | // return bucket==null ? null : bucket.convert(source, context); |
| 178 | // } |
| 179 | // |
| 180 | // }; |
| 181 | |
| 182 | Collection<AtomicConverter<? extends Object,? extends Object>> atomicConverters = new ArrayList<AtomicConverter<? extends Object,? extends Object>>(); |
| 183 | |
| 184 | /** |
| 185 | * Map of resolved converters: Collection[source, target] -> ConverterClosure. |
| 186 | */ |
| 187 | Map<ConverterKey<?,?>, Object> converters = new HashMap<ConverterKey<?,?>, Object>(); |
| 188 | |
| 189 | Set<Class<?>> introspectedTargetTypes = new HashSet<Class<?>>(); |
| 190 | |
| 191 | Set<Class<?>> introspectedSourceTypes = new HashSet<Class<?>>(); |
| 192 | |
| 193 | Collection<Converter> subConverters = new ArrayList<Converter>(); |
| 194 | Collection<ConverterPart> parts = new ArrayList<ConverterPart>(); |
| 195 | |
| 196 | /** |
| 197 | * Map of resolved chaining converters: Collection[source, target] -> ConverterClosure. |
| 198 | */ |
| 199 | // Map chainingConverters = new HashMap(); |
| 200 | |
| 201 | @SuppressWarnings("unchecked") |
| 202 | synchronized <S, T> ConvertersBucket<S, T> findConverter(Class<S> sourceType, final Class<T> targetType) { |
| 203 | ConverterKey<S, T> key = new ConverterKey(sourceType, targetType); |
| 204 | Object ret = converters.get(key); |
| 205 | if (Boolean.FALSE.equals(ret)) { // Indicates that previous converter resolution didn't yield results. |
| 206 | return null; |
| 207 | } |
| 208 | |
| 209 | if (ret == null) { |
| 210 | if (!targetType.isInterface() && introspectedTargetTypes.add(targetType)) { |
| 211 | atomicConverters.addAll(ReflectionConverter.discoverConstructorConverters(targetType)); |
| 212 | } |
| 213 | |
| 214 | class ConverterEntry implements Comparable<ConverterEntry> { |
| 215 | public ConverterEntry(AtomicConverter<? extends Object,? extends Object> converter, int affinity, int position) { |
| 216 | super(); |
| 217 | this.converter = converter; |
| 218 | this.affinity = affinity; |
| 219 | this.position = position; |
| 220 | } |
| 221 | AtomicConverter<? extends Object, ? extends Object> converter; |
| 222 | int affinity; |
| 223 | int position; |
| 224 | public int compareTo(ConverterEntry obj) { |
| 225 | int cret = affinity - ((ConverterEntry) obj).affinity; |
| 226 | if (cret==0) { |
| 227 | return position - ((ConverterEntry) obj).position; |
| 228 | } |
| 229 | return cret; |
| 230 | } |
| 231 | } |
| 232 | |
| 233 | final List<ConverterEntry> theConverters = new ArrayList<ConverterEntry>(); |
| 234 | |
| 235 | for (AtomicConverter<? extends Object,? extends Object> ac: atomicConverters) { |
| 236 | int position = 0; |
| 237 | if (ac.getSourceType().isAssignableFrom(sourceType) && targetType.isAssignableFrom(ac.getTargetType()) ) { |
| 238 | Integer newSourceAffinity = DuckConverterFactory.classAffinity(sourceType, ac.getSourceType()); |
| 239 | Integer newTargetAffinity = DuckConverterFactory.classAffinity(ac.getTargetType(), targetType); |
| 240 | if (newSourceAffinity==null || newTargetAffinity==null) { |
| 241 | throw new IllegalArgumentException("Something is wrong - source and target affinities are null"); |
| 242 | } |
| 243 | theConverters.add(new ConverterEntry(ac, newSourceAffinity.intValue()+newTargetAffinity.intValue(), ++position)); |
| 244 | } |
| 245 | } |
| 246 | if (theConverters.isEmpty() && parts.isEmpty() && subConverters.isEmpty()) { |
| 247 | converters.put(key, Boolean.FALSE); |
| 248 | } else { |
| 249 | Collections.sort(theConverters); |
| 250 | ret = new ConvertersBucket<S,T>() { |
| 251 | |
| 252 | public T convert(S source, Context context) { |
| 253 | for (ConverterEntry ce: theConverters) { |
| 254 | AtomicConverter<S, T> theConverter = (AtomicConverter<S, T>) ce.converter; |
| 255 | T ret = (T) theConverter.convert(source, master, context, classLoader); |
| 256 | if (ret!=null) { |
| 257 | return ret; |
| 258 | } |
| 259 | } |
| 260 | |
| 261 | for (ConverterPart part: parts) { |
| 262 | Object ret = part.convert(source, targetType, context, master); |
| 263 | if (ret!=null) { |
| 264 | return (T) ret; |
| 265 | } |
| 266 | } |
| 267 | |
| 268 | for (Converter subConverter: subConverters) { |
| 269 | Object ret = subConverter.convert(source, targetType, context); |
| 270 | if (ret!=null) { |
| 271 | return (T) ret; |
| 272 | } |
| 273 | } |
| 274 | |
| 275 | return null; |
| 276 | } |
| 277 | |
| 278 | }; |
| 279 | converters.put(key, ret); |
| 280 | } |
| 281 | } |
| 282 | |
| 283 | return (ConvertersBucket<S, T>) ret; |
| 284 | } |
| 285 | |
| 286 | synchronized <S, T> ConvertersBucket<S,T> findChainingConverter(Class<S> sourceType, Class<T> targetType) { |
| 287 | ConvertersBucket<S,T> ret = findConverter(sourceType, targetType); |
| 288 | if (ret!=null) { |
| 289 | return ret; |
| 290 | } |
| 291 | |
| 292 | // TODO - Resolve chain. |
| 293 | return ret; |
| 294 | } |
| 295 | |
| 296 | <S,T> void addAnnotationConverters(Class<S> source) { |
| 297 | if (introspectedSourceTypes.add(source)) { |
| 298 | Z: for (Method m: source.getMethods()) { |
| 299 | if (m.getAnnotation(ConverterMethod.class)!=null && !void.class.equals(m.getReturnType())) { |
| 300 | for (Class<?> pt: m.getParameterTypes()) { |
| 301 | if (!(Context.class.equals(pt) || Converter.class.equals(pt))) { |
| 302 | continue Z; |
| 303 | } |
| 304 | } |
| 305 | final Method converterMethod = m; |
| 306 | @SuppressWarnings("unchecked") |
| 307 | AtomicConverterBase<S, T> converter = new AtomicConverterBase<S, T>(source, (Class<T>) m.getReturnType()) { |
| 308 | |
| 309 | @Override |
| 310 | public T convert(S source, Converter master, Context context, ClassLoader classLoader) { |
| 311 | try { |
| 312 | Class<?>[] pt = converterMethod.getParameterTypes(); |
| 313 | Object[] args = new Object[pt.length]; |
| 314 | for (int i=0; i<pt.length; ++i) { |
| 315 | if (Context.class.equals(pt[i])) { |
| 316 | args[i] = context; |
| 317 | } else if (Converter.class.equals(pt[i])) { |
| 318 | args[i] = master; |
| 319 | } |
| 320 | } |
| 321 | return (T) converterMethod.invoke(source, args); |
| 322 | } catch (Exception e) { |
| 323 | throw new ConversionException(e); |
| 324 | } |
| 325 | } |
| 326 | }; |
| 327 | atomicConverters.add(converter); |
| 328 | } |
| 329 | } |
| 330 | } |
| 331 | } |
| 332 | |
| 333 | @SuppressWarnings("unchecked") |
| 334 | void addConverters(final Object provider) { |
| 335 | if (provider instanceof AtomicConverter) { |
| 336 | atomicConverters.add((AtomicConverter<Object, Object>) provider); |
| 337 | } else if (provider instanceof AtomicConvertersBundle) { |
| 338 | atomicConverters.addAll(((AtomicConvertersBundle) provider).getConverters()); |
| 339 | } else if (provider instanceof Collection<?>) { |
| 340 | for (Object obj: (Collection<?>) provider) { |
| 341 | addConverters(obj); |
| 342 | } |
| 343 | } else if (provider instanceof Converter) { |
| 344 | subConverters.add((Converter) provider); |
| 345 | } else if (provider instanceof ConverterPart) { |
| 346 | parts.add((ConverterPart) provider); |
| 347 | } else { // Introspection |
| 348 | Class pClass = provider.getClass(); |
| 349 | Method[] methods = pClass.getMethods(); |
| 350 | for (int i=0; i<methods.length; ++i) { |
| 351 | final Method method = methods[i]; |
| 352 | if (CONVERT.equals(method.getName()) && !void.class.equals(method.getReturnType())) { |
| 353 | Class[] pTypes = method.getParameterTypes(); |
| 354 | if (pTypes.length == 1) { |
| 355 | atomicConverters.add(new AtomicConverterBase(pTypes[0], method.getReturnType()) { |
| 356 | |
| 357 | public Object convert(Object source, Converter master, Context context, ClassLoader classLoader) { |
| 358 | try { |
| 359 | return method.invoke(provider, new Object[] {source}); |
| 360 | } catch (IllegalAccessException e) { |
| 361 | throw new ConversionException(e); |
| 362 | } catch (InvocationTargetException e) { |
| 363 | throw new ConversionException(e); |
| 364 | } |
| 365 | } |
| 366 | |
| 367 | }); |
| 368 | } else if (pTypes.length == 2 && Converter.class.equals(pTypes[1])) { |
| 369 | atomicConverters.add(new AtomicConverterBase(pTypes[0], method.getReturnType()) { |
| 370 | |
| 371 | public Object convert(Object source, Converter master, Context context, ClassLoader classLoader) { |
| 372 | try { |
| 373 | return method.invoke(provider, new Object[] {source, master}); |
| 374 | } catch (IllegalAccessException e) { |
| 375 | throw new ConversionException(e); |
| 376 | } catch (InvocationTargetException e) { |
| 377 | throw new ConversionException(e); |
| 378 | } |
| 379 | } |
| 380 | |
| 381 | }); |
| 382 | |
| 383 | } else if (pTypes.length == 2 && Context.class.equals(pTypes[1])) { |
| 384 | atomicConverters.add(new AtomicConverterBase(pTypes[0], method.getReturnType()) { |
| 385 | |
| 386 | public Object convert(Object source, Converter master, Context context, ClassLoader classLoader) { |
| 387 | try { |
| 388 | return method.invoke(provider, new Object[] {source, context}); |
| 389 | } catch (IllegalAccessException e) { |
| 390 | throw new ConversionException(e); |
| 391 | } catch (InvocationTargetException e) { |
| 392 | throw new ConversionException(e); |
| 393 | } |
| 394 | } |
| 395 | |
| 396 | }); |
| 397 | |
| 398 | } else if (pTypes.length == 3 && Converter.class.equals(pTypes[1]) && Context.class.equals(pTypes[2])) { |
| 399 | atomicConverters.add(new AtomicConverterBase(pTypes[0], method.getReturnType()) { |
| 400 | |
| 401 | public Object convert(Object source, Converter master, Context context, ClassLoader classLoader) { |
| 402 | try { |
| 403 | return method.invoke(provider, new Object[] {source, master, context}); |
| 404 | } catch (IllegalAccessException e) { |
| 405 | throw new ConversionException(e); |
| 406 | } catch (InvocationTargetException e) { |
| 407 | throw new ConversionException(e); |
| 408 | } |
| 409 | } |
| 410 | |
| 411 | }); |
| 412 | |
| 413 | } |
| 414 | |
| 415 | } |
| 416 | } |
| 417 | } |
| 418 | } |
| 419 | |
| 420 | } |
| 421 | |
| 422 | /** |
| 423 | * Map of resolved converters: ClassLoader -> ClassLoaderConvertersEntry. |
| 424 | */ |
| 425 | private static Map<ClassLoader, ClassLoaderConvertersEntry> classLoaderEntries = new HashMap<ClassLoader, ClassLoaderConvertersEntry>(); |
| 426 | |
| 427 | /** |
| 428 | * Converts source to target type using Java 6 service loading for AtomicConverterBundle, AtomicConverter, and Converter services |
| 429 | * If no converter is found, this method performs converter discovery through |
| 430 | * constructors if target type is a class and through duck conversion if target |
| 431 | * type is an interface. |
| 432 | * @param source Source object. |
| 433 | * @param targetType Target type. |
| 434 | * @param context Conversion context. |
| 435 | * @param classLoader Class loader. |
| 436 | * @return Source object converted to target type or null if no converter |
| 437 | * is available for source/targetType combination |
| 438 | * @throws ConversionException |
| 439 | */ |
| 440 | public static <S, T> T convert(S source, Class<T> targetType, Context context, ClassLoader classLoader) throws ConversionException { |
| 441 | return convert(source, targetType, context, false, classLoader); |
| 442 | } |
| 443 | |
| 444 | /** |
| 445 | * Converts source to target type using Java 6 service loading for AtomicConverterBundle, AtomicConverter, and Converter services |
| 446 | * If no converter is found, this method performs converter discovery through |
| 447 | * constructors if target type is a class and through duck conversion if target |
| 448 | * type is an interface. |
| 449 | * @param source Source object. |
| 450 | * @param targetType Target type. |
| 451 | * @param chain If true, the converter will attempt to build a chain of |
| 452 | * conversions from source type to target type. |
| 453 | * For example, StringBuffer doesn't have a constructor from Integer. If chain |
| 454 | * is <code>false</code> then this method will return <code>null</code>. If |
| 455 | * <code>chain</code> is true, then the converter will convert Integer to String |
| 456 | * and then will create StringBuffer from it. If multiple conversion chains |
| 457 | * are available, the shortest is chosen. |
| 458 | * @return Source object converted to target type or null if no converter |
| 459 | * is available for source/targetType combination |
| 460 | * @throws ConversionException |
| 461 | */ |
| 462 | @SuppressWarnings("unchecked") |
| 463 | private static <S, T> T convert(S source, Class<T> targetType, Context context, boolean chain, ClassLoader classLoader) throws ConversionException { |
| 464 | if (source==null) { |
| 465 | return null; |
| 466 | } |
| 467 | |
| 468 | if (targetType.isInstance(source)) { |
| 469 | return (T) source; |
| 470 | } |
| 471 | |
| 472 | if (source instanceof Adaptable) { |
| 473 | T ret = ((Adaptable) source).getAdapter(targetType, context); |
| 474 | if (ret!=null) { |
| 475 | return ret; |
| 476 | } |
| 477 | } |
| 478 | |
| 479 | ConverterClosure<S, T> converter = (ConverterClosure<S, T>) getConverter(source.getClass(), targetType, context, chain, classLoader); |
| 480 | |
| 481 | if (converter!=null) { |
| 482 | return converter.convert(source); |
| 483 | } |
| 484 | |
| 485 | ConverterClosure<S, Adaptable> adaptableConverter = (ConverterClosure<S, Adaptable>) getConverter(source.getClass(), Adaptable.class, context, chain, classLoader); |
| 486 | if (adaptableConverter==null) { |
| 487 | return null; |
| 488 | } |
| 489 | |
| 490 | Adaptable adaptable = adaptableConverter.convert(source); |
| 491 | return adaptable==null ? null : adaptable.getAdapter(targetType, context); |
| 492 | } |
| 493 | |
| 494 | /** |
| 495 | * Converts source to target type using Java 6 service loading for AtomicConverterBundle, AtomicConverter, and Converter services |
| 496 | * If no converter is found, this method performs converter discovery through |
| 497 | * constructors if target type is a class and through duck conversion if target |
| 498 | * type is an interface. |
| 499 | * @param sourceType Source type. |
| 500 | * @param targetType Target type. |
| 501 | * @return Converter from source type to target type, or null if such converter |
| 502 | * is not available. |
| 503 | * @throws ConversionException |
| 504 | */ |
| 505 | public static <S, T> ConverterClosure<S, T> getConverter(Class<S> sourceType, Class<T> targetType) { |
| 506 | return getConverter(sourceType, targetType, null, false, null); |
| 507 | } |
| 508 | |
| 509 | /** |
| 510 | * Converts source to target type using Java 6 service loading for AtomicConverterBundle, AtomicConverter, and Converter services |
| 511 | * If no converter is found, this method performs converter discovery through |
| 512 | * constructors if target type is a class and through duck conversion if target |
| 513 | * type is an interface. |
| 514 | * @param sourceType Source type. |
| 515 | * @param targetType Target type. |
| 516 | * @param classLoader Class loader to retrieve converters from. |
| 517 | * @return Converter from source type to target type, or null if such converter |
| 518 | * is not available. |
| 519 | * @throws ConversionException |
| 520 | */ |
| 521 | public static <S, T> ConverterClosure<S, T> getConverter(Class<S> sourceType, Class<T> targetType, ClassLoader classLoader) { |
| 522 | return getConverter(sourceType, targetType, null, false, classLoader); |
| 523 | } |
| 524 | |
| 525 | /** |
| 526 | * Converts source to target type using Java 6 service loading for AtomicConverterBundle, AtomicConverter, and Converter services |
| 527 | * If no converter is found, this method performs converter discovery through |
| 528 | * constructors if target type is a class and through duck conversion if target |
| 529 | * type is an interface. |
| 530 | * @param sourceType Source type. |
| 531 | * @param targetType Target type. |
| 532 | * @param context Conversion context. |
| 533 | * @return Converter from source type to target type, or null if such converter |
| 534 | * is not available. |
| 535 | * @throws ConversionException |
| 536 | */ |
| 537 | public static <S, T> ConverterClosure<S,T> getConverter(Class<S> sourceType, Class<T> targetType, Context context) { |
| 538 | return getConverter(sourceType, targetType, context, false, null); |
| 539 | } |
| 540 | |
| 541 | /** |
| 542 | * Converts source to target type using Java 6 service loading for AtomicConverterBundle, AtomicConverter, and Converter services |
| 543 | * If no converter is found, this method performs converter discovery through |
| 544 | * constructors if target type is a class and through duck conversion if target |
| 545 | * type is an interface. |
| 546 | * @param sourceType Source type. |
| 547 | * @param targetType Target type. |
| 548 | * @param context Conversion context. |
| 549 | * @param classLoader Class loader to retrieve converters from. |
| 550 | * @return Converter from source type to target type, or null if such converter |
| 551 | * is not available. |
| 552 | * @throws ConversionException |
| 553 | */ |
| 554 | public static <S, T> ConverterClosure<S,T> getConverter(Class<S> sourceType, Class<T> targetType, Context context, ClassLoader classLoader) { |
| 555 | return getConverter(sourceType, targetType, context, false, classLoader); |
| 556 | } |
| 557 | |
| 558 | private static ClassLoader promote(ClassLoader present, ClassLoader candidate) { |
| 559 | ClassLoader ret = DuckConverterFactory.getChildClassLoader(present, candidate); |
| 560 | return ret==null ? present : ret; |
| 561 | } |
| 562 | |
| 563 | /** |
| 564 | * |
| 565 | * @param sourceType |
| 566 | * @param targetType |
| 567 | * @param context |
| 568 | * @param chain If true, the converter will attempt to build a chain of |
| 569 | * conversions from source type to target type. |
| 570 | * For example, StringBuffer doesn't have a constructor from Integer. If chain |
| 571 | * is <code>false</code> then this method will return <code>null</code>. If |
| 572 | * <code>chain</code> is true, then the converter will convert Integer to String |
| 573 | * and then will create StringBuffer from it. If multiple conversion chains |
| 574 | * are available, the shortest is chosen. |
| 575 | * @param classLoader |
| 576 | * @return |
| 577 | */ |
| 578 | @SuppressWarnings("unchecked") |
| 579 | private static <S, T> ConverterClosure<S, T> getConverter(Class<S> sourceType, Class<T> targetType, final Context context, boolean chain, ClassLoader pClassLoader) { |
| 580 | if (pClassLoader==null) { |
| 581 | pClassLoader = ConvertingService.class.getClassLoader(); |
| 582 | } |
| 583 | ClassLoader classLoader = promote(pClassLoader, promote(targetType.getClassLoader(), sourceType.getClassLoader())); |
| 584 | |
| 585 | ClassLoaderConvertersEntry clce; |
| 586 | synchronized (classLoaderEntries) { |
| 587 | clce = classLoaderEntries.get(classLoader); |
| 588 | if (clce == null) { |
| 589 | clce = new ClassLoaderConvertersEntry(classLoader); |
| 590 | for (Object provider: ServiceLoader.load(AtomicConvertersBundle.class, classLoader)) { |
| 591 | clce.addConverters(provider); |
| 592 | } |
| 593 | for (Object provider: ServiceLoader.load(AtomicConverter.class, classLoader)) { |
| 594 | clce.addConverters(provider); |
| 595 | } |
| 596 | for (Object provider: ServiceLoader.load(Converter.class, classLoader)) { |
| 597 | clce.addConverters(provider); |
| 598 | } |
| 599 | |
| 600 | for (Object provider: ServiceLoader.load(ConverterPart.class, classLoader)) { |
| 601 | clce.addConverters(provider); |
| 602 | } |
| 603 | // TODO - Converter factories which may create converter (closure) or return null depending on context. |
| 604 | classLoaderEntries.put(classLoader, clce); |
| 605 | } |
| 606 | clce.addAnnotationConverters(sourceType); |
| 607 | } |
| 608 | final ConvertersBucket bucket = chain ? clce.findChainingConverter(sourceType, targetType) : clce.findConverter(sourceType, targetType); |
| 609 | return bucket==null ? null : new ConverterClosure() { |
| 610 | |
| 611 | public Object convert(Object source) { |
| 612 | return bucket.convert(source, context); |
| 613 | } |
| 614 | |
| 615 | }; |
| 616 | } |
| 617 | } |