Source Code Cross Referenced for LocalUtil.java in  » Ajax » dwr » org » directwebremoting » util » Java Source Code / Java DocumentationJava Source Code and Java Documentation

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Java Source Code / Java Documentation » Ajax » dwr » org.directwebremoting.util 
Source Cross Referenced  Class Diagram Java Document (Java Doc) 


001:        /*
002:         * Copyright 2005 Joe Walker
003:         *
004:         * Licensed under the Apache License, Version 2.0 (the "License");
005:         * you may not use this file except in compliance with the License.
006:         * You may obtain a copy of the License at
007:         *
008:         *     http://www.apache.org/licenses/LICENSE-2.0
009:         *
010:         * Unless required by applicable law or agreed to in writing, software
011:         * distributed under the License is distributed on an "AS IS" BASIS,
012:         * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013:         * See the License for the specific language governing permissions and
014:         * limitations under the License.
015:         */
016:        package org.directwebremoting.util;
017:
018:        import java.io.IOException;
019:        import java.io.UnsupportedEncodingException;
020:        import java.io.Closeable;
021:        import java.lang.reflect.Field;
022:        import java.lang.reflect.InvocationTargetException;
023:        import java.lang.reflect.Method;
024:        import java.net.URLDecoder;
025:        import java.util.ArrayList;
026:        import java.util.Arrays;
027:        import java.util.HashSet;
028:        import java.util.List;
029:        import java.util.Locale;
030:        import java.util.Map;
031:        import java.util.Set;
032:
033:        import javax.servlet.ServletConfig;
034:        import javax.servlet.ServletContext;
035:        import javax.servlet.http.HttpServletRequest;
036:        import javax.servlet.http.HttpServletResponse;
037:        import javax.servlet.http.HttpSession;
038:        import javax.xml.transform.TransformerFactoryConfigurationError;
039:
040:        import org.apache.commons.logging.LogFactory;
041:        import org.apache.commons.logging.Log;
042:
043:        /**
044:         * Various utilities, stuff that we're still surprised isn't in the JDK, and
045:         * stuff that perhaps is borderline JDK material, but isn't really pure DWR
046:         * either.
047:         * @author Joe Walker [joe at getahead dot ltd dot uk]
048:         */
049:        public final class LocalUtil {
050:            /**
051:             * splitInbound() returns the type info in this parameter
052:             */
053:            public static final int INBOUND_INDEX_TYPE = 0;
054:
055:            /**
056:             * splitInbound() returns the value info in this parameter
057:             */
058:            public static final int INBOUND_INDEX_VALUE = 1;
059:
060:            /**
061:             * Prevent instantiation
062:             */
063:            private LocalUtil() {
064:            }
065:
066:            /**
067:             * Create a string by joining the array elements together with the separator
068:             * in-between each element. A null (in the array or as a separator) is
069:             * treated as an empty string.
070:             * @param array The array of elements to join
071:             * @param separator The string sequence to place between array elements
072:             * @return A string containing the joined elements
073:             */
074:            public static String join(Object[] array, String separator) {
075:                if (array == null) {
076:                    return null;
077:                }
078:
079:                if (separator == null) {
080:                    separator = "";
081:                }
082:
083:                StringBuffer buffer = new StringBuffer();
084:                boolean isFirst = true;
085:
086:                for (Object object : array) {
087:                    if (isFirst) {
088:                        isFirst = false;
089:                    } else {
090:                        buffer.append(separator);
091:                    }
092:
093:                    if (object != null) {
094:                        buffer.append(object);
095:                    }
096:                }
097:
098:                return buffer.toString();
099:            }
100:
101:            /**
102:             * Determines if the specified string is permissible as a Java identifier.
103:             * Returns true if the string is non-null, non-zero length with a Java
104:             * identifier start as the first character and Java identifier parts in all
105:             * remaining characters.
106:             * @param test the string to be tested.
107:             * @return true if the string is a Java identifier, false otherwise.
108:             * @see java.lang.Character#isJavaIdentifierPart(char)
109:             * @see java.lang.Character#isJavaIdentifierStart(char)
110:             */
111:            public static boolean isJavaIdentifier(String test) {
112:                if (test == null || test.length() == 0) {
113:                    return false;
114:                }
115:
116:                if (!Character.isJavaIdentifierStart(test.charAt(0))
117:                        && test.charAt(0) != '_') {
118:                    return false;
119:                }
120:
121:                for (int i = 1; i < test.length(); i++) {
122:                    if (!Character.isJavaIdentifierPart(test.charAt(i))
123:                            && test.charAt(i) != '_') {
124:                        return false;
125:                    }
126:                }
127:
128:                return true;
129:            }
130:
131:            /**
132:             * Determines if the specified string contains only Unicode letters or
133:             * digits as defined by {@link Character#isLetterOrDigit(char)}
134:             * @param test The string to test
135:             * @return true if the string is non-null, non-empty and contains only
136:             * characters that are unicode letters or digits
137:             * @see Character#isLetterOrDigit(char)
138:             */
139:            public static boolean isLetterOrDigitOrUnderline(String test) {
140:                if (test == null || test.length() == 0) {
141:                    return false;
142:                }
143:
144:                for (int i = 0; i < test.length(); i++) {
145:                    if (!Character.isLetterOrDigit(test.charAt(i))
146:                            && test.charAt(i) != '_') {
147:                        return false;
148:                    }
149:                }
150:
151:                return true;
152:            }
153:
154:            /**
155:             * True if c1 is java.lang.Boolean and c2 is boolean, etc.
156:             * @param c1 the first class to test
157:             * @param c2 the second class to test
158:             * @return true if the classes are equivalent
159:             */
160:            public static boolean isEquivalent(Class<?> c1, Class<?> c2) {
161:                if (c1 == Boolean.class || c1 == Boolean.TYPE) {
162:                    return c2 == Boolean.class || c2 == Boolean.TYPE;
163:                } else if (c1 == Byte.class || c1 == Byte.TYPE) {
164:                    return c2 == Byte.class || c2 == Byte.TYPE;
165:                } else if (c1 == Character.class || c1 == Character.TYPE) {
166:                    return c2 == Character.class || c2 == Character.TYPE;
167:                } else if (c1 == Short.class || c1 == Short.TYPE) {
168:                    return c2 == Short.class || c2 == Short.TYPE;
169:                } else if (c1 == Integer.class || c1 == Integer.TYPE) {
170:                    return c2 == Integer.class || c2 == Integer.TYPE;
171:                } else if (c1 == Long.class || c1 == Long.TYPE) {
172:                    return c2 == Long.class || c2 == Long.TYPE;
173:                } else if (c1 == Float.class || c1 == Float.TYPE) {
174:                    return c2 == Float.class || c2 == Float.TYPE;
175:                } else if (c1 == Double.class || c1 == Double.TYPE) {
176:                    return c2 == Double.class || c2 == Double.TYPE;
177:                } else if (c1 == Void.class || c1 == Void.TYPE) {
178:                    return c2 == Void.class || c2 == Void.TYPE;
179:                }
180:
181:                return false;
182:            }
183:
184:            /**
185:             * @param type The class to de-primitivize
186:             * @return The non-primitive version of the class
187:             */
188:            public static Class<?> getNonPrimitiveType(Class<?> type) {
189:                if (!type.isPrimitive()) {
190:                    return type;
191:                } else if (type == Boolean.TYPE) {
192:                    return Boolean.class;
193:                } else if (type == Byte.TYPE) {
194:                    return Byte.class;
195:                } else if (type == Character.TYPE) {
196:                    return Character.class;
197:                } else if (type == Short.TYPE) {
198:                    return Short.class;
199:                } else if (type == Integer.TYPE) {
200:                    return Integer.class;
201:                } else if (type == Long.TYPE) {
202:                    return Long.class;
203:                } else if (type == Float.TYPE) {
204:                    return Float.class;
205:                } else if (type == Double.TYPE) {
206:                    return Double.class;
207:                } else if (type == Void.TYPE) {
208:                    return Void.class;
209:                }
210:
211:                return null;
212:            }
213:
214:            /**
215:             * Add headers to prevent browsers and proxies from caching this reply.
216:             * @param resp The response to add headers to
217:             */
218:            public static void addNoCacheHeaders(HttpServletResponse resp) {
219:                // Set standard HTTP/1.1 no-cache headers.
220:                resp.setHeader("Cache-Control",
221:                        "no-store, no-cache, must-revalidate");
222:
223:                // Set IE extended HTTP/1.1 no-cache headers (use addHeader).
224:                resp.addHeader("Cache-Control", "post-check=0, pre-check=0");
225:
226:                // Set standard HTTP/1.0 no-cache header.
227:                resp.setHeader("Pragma", "no-cache");
228:
229:                // Set to expire far in the past. Prevents caching at the proxy server
230:                resp.setHeader("Expires", "Sat, 6 May 1995 12:00:00 GMT");
231:            }
232:
233:            /**
234:             * Is this class one that we auto fill, so the user can ignore?
235:             * @param paramType The type to test
236:             * @return true if the type is a Servlet type
237:             */
238:            public static boolean isServletClass(Class<?> paramType) {
239:                return paramType == HttpServletRequest.class
240:                        || paramType == HttpServletResponse.class
241:                        || paramType == ServletConfig.class
242:                        || paramType == ServletContext.class
243:                        || paramType == HttpSession.class;
244:            }
245:
246:            /**
247:             * URL decode a value.
248:             * {@link URLDecoder#decode(String, String)} throws an
249:             * {@link UnsupportedEncodingException}, which is silly given that the most
250:             * common use case will be to pass in "UTF-8"
251:             * @param value The string to decode
252:             * @return The decoded string
253:             */
254:            public static String decode(String value) {
255:                try {
256:                    return URLDecoder.decode(value, "UTF-8");
257:                } catch (UnsupportedEncodingException ex) {
258:                    log.error("UTF-8 is not a valid char sequence?", ex);
259:                    return value;
260:                }
261:            }
262:
263:            /**
264:             * Set use reflection to set the setters on the object called by the keys
265:             * in the params map with the corresponding values
266:             * @param object The object to setup
267:             * @param params The settings to use
268:             * @param ignore List of keys to not warn about if they are not properties
269:             *               Note only the warning is skipped, we still try the setter
270:             */
271:            public static void setParams(Object object, Map<String, ?> params,
272:                    List<String> ignore) {
273:                for (Map.Entry<String, ?> entry : params.entrySet()) {
274:                    String key = entry.getKey();
275:                    Object value = entry.getValue();
276:
277:                    try {
278:                        setProperty(object, key, value);
279:                    } catch (NoSuchMethodException ex) {
280:                        if (ignore != null && !ignore.contains(key)) {
281:                            log.warn("No property '" + key + "' on "
282:                                    + object.getClass().getName());
283:                        }
284:                    } catch (InvocationTargetException ex) {
285:                        log.warn("Error setting " + key + "=" + value + " on "
286:                                + object.getClass().getName(), ex
287:                                .getTargetException());
288:                    } catch (Exception ex) {
289:                        log.warn("Error setting " + key + "=" + value + " on "
290:                                + object.getClass().getName(), ex);
291:                    }
292:                }
293:            }
294:
295:            /**
296:             * Set a property on an object using reflection
297:             * @param object The object to call the setter on
298:             * @param key The name of the property to set.
299:             * @param value The new value to use for the property
300:             * @throws NoSuchMethodException Passed on from reflection code
301:             * @throws SecurityException Passed on from reflection code
302:             * @throws IllegalAccessException Passed on from reflection code
303:             * @throws IllegalArgumentException Passed on from reflection code
304:             * @throws InvocationTargetException Passed on from reflection code
305:             */
306:            public static void setProperty(Object object, String key,
307:                    Object value) throws NoSuchMethodException,
308:                    SecurityException, IllegalAccessException,
309:                    IllegalArgumentException, InvocationTargetException {
310:                Class<? extends Object> real = object.getClass();
311:
312:                String setterName = "set"
313:                        + key.substring(0, 1).toUpperCase(Locale.ENGLISH)
314:                        + key.substring(1);
315:
316:                try {
317:                    // Can we work with whatever type we were given?
318:                    Method method = real
319:                            .getMethod(setterName, value.getClass());
320:                    method.invoke(object, value);
321:                    return;
322:                } catch (NoSuchMethodException ex) {
323:                    // If it is a string then next we try to coerce it to the right type
324:                    // otherwise we give up.
325:                    if (!(value instanceof  String)) {
326:                        throw ex;
327:                    }
328:                }
329:
330:                for (Method setter : real.getMethods()) {
331:                    if (setter.getName().equals(setterName)
332:                            && setter.getParameterTypes().length == 1) {
333:                        Class<?> propertyType = setter.getParameterTypes()[0];
334:                        try {
335:                            Object param = simpleConvert((String) value,
336:                                    propertyType);
337:                            setter.invoke(object, param);
338:                            return;
339:                        } catch (IllegalArgumentException ex) {
340:                            // The conversion failed - it was speculative anyway so we
341:                            // don't worry now
342:                        }
343:                    }
344:                }
345:
346:                throw new NoSuchMethodException(
347:                        "Failed to find a property called: " + key + " on "
348:                                + object.getClass().getName());
349:            }
350:
351:            /**
352:             * Can the type be used in a call to {@link #simpleConvert(String, Class)}?
353:             * @param paramType The type to test
354:             * @return true if the type is acceptable to simpleConvert()
355:             */
356:            public static boolean isTypeSimplyConvertable(Class<?> paramType) {
357:                return paramType == String.class || paramType == Integer.class
358:                        || paramType == Integer.TYPE
359:                        || paramType == Short.class || paramType == Short.TYPE
360:                        || paramType == Byte.class || paramType == Byte.TYPE
361:                        || paramType == Long.class || paramType == Long.TYPE
362:                        || paramType == Float.class || paramType == Float.TYPE
363:                        || paramType == Double.class
364:                        || paramType == Double.TYPE
365:                        || paramType == Character.class
366:                        || paramType == Character.TYPE
367:                        || paramType == Boolean.class
368:                        || paramType == Boolean.TYPE;
369:            }
370:
371:            /**
372:             * A very simple conversion function for all the IoC style setup and
373:             * reflection that we are doing.
374:             * @param value The value to convert
375:             * @param paramType The type to convert to. Currently any primitive types and
376:             * String are supported.
377:             * @return The converted object.
378:             */
379:            @SuppressWarnings("unchecked")
380:            public static <T> T simpleConvert(String value, Class<T> paramType) {
381:                if (paramType == String.class) {
382:                    return (T) value;
383:                }
384:
385:                if (paramType == Character.class || paramType == Character.TYPE) {
386:                    value = LocalUtil.decode(value);
387:                    if (value.length() == 1) {
388:                        return (T) Character.valueOf(value.charAt(0));
389:                    } else {
390:                        throw new IllegalArgumentException(
391:                                "Can't more than one character in string - can't convert to char: '"
392:                                        + value + "'");
393:                    }
394:                }
395:
396:                String trimValue = value.trim();
397:
398:                if (paramType == Boolean.class) {
399:                    if (trimValue.length() == 0) {
400:                        return null;
401:                    }
402:
403:                    return (T) Boolean.valueOf(trimValue);
404:                }
405:
406:                if (paramType == Boolean.TYPE) {
407:                    return (T) Boolean.valueOf(trimValue);
408:                }
409:
410:                if (paramType == Integer.class) {
411:                    if (trimValue.length() == 0) {
412:                        return null;
413:                    }
414:
415:                    return (T) Integer.valueOf(trimValue);
416:                }
417:
418:                if (paramType == Integer.TYPE) {
419:                    if (trimValue.length() == 0) {
420:                        return (T) Integer.valueOf(0);
421:                    }
422:
423:                    return (T) Integer.valueOf(trimValue);
424:                }
425:
426:                if (paramType == Short.class) {
427:                    if (trimValue.length() == 0) {
428:                        return null;
429:                    }
430:
431:                    return (T) Short.valueOf(trimValue);
432:                }
433:
434:                if (paramType == Short.TYPE) {
435:                    if (trimValue.length() == 0) {
436:                        return (T) Short.valueOf((short) 0);
437:                    }
438:
439:                    return (T) Short.valueOf(trimValue);
440:                }
441:
442:                if (paramType == Byte.class) {
443:                    if (trimValue.length() == 0) {
444:                        return null;
445:                    }
446:
447:                    return (T) Byte.valueOf(trimValue);
448:                }
449:
450:                if (paramType == Byte.TYPE) {
451:                    if (trimValue.length() == 0) {
452:                        return (T) Byte.valueOf((byte) 0);
453:                    }
454:
455:                    return (T) Byte.valueOf(trimValue);
456:                }
457:
458:                if (paramType == Long.class) {
459:                    if (trimValue.length() == 0) {
460:                        return null;
461:                    }
462:
463:                    return (T) Long.valueOf(trimValue);
464:                }
465:
466:                if (paramType == Long.TYPE) {
467:                    if (trimValue.length() == 0) {
468:                        return (T) Long.valueOf(0);
469:                    }
470:
471:                    return (T) Long.valueOf(trimValue);
472:                }
473:
474:                if (paramType == Float.class) {
475:                    if (trimValue.length() == 0) {
476:                        return null;
477:                    }
478:
479:                    return (T) Float.valueOf(trimValue);
480:                }
481:
482:                if (paramType == Float.TYPE) {
483:                    if (trimValue.length() == 0) {
484:                        return (T) Float.valueOf(0);
485:                    }
486:
487:                    return (T) Float.valueOf(trimValue);
488:                }
489:
490:                if (paramType == Double.class) {
491:                    if (trimValue.length() == 0) {
492:                        return null;
493:                    }
494:
495:                    return (T) Double.valueOf(trimValue);
496:                }
497:
498:                if (paramType == Double.TYPE) {
499:                    if (trimValue.length() == 0) {
500:                        return (T) Double.valueOf(0.0D);
501:                    }
502:
503:                    return (T) Double.valueOf(trimValue);
504:                }
505:
506:                throw new IllegalArgumentException(
507:                        "Unsupported conversion type: " + paramType.getName());
508:            }
509:
510:            /**
511:             * Is this object property one that we can use in a JSON style or do we need
512:             * to get fancy. i.e does it contain only letters and numbers with an
513:             * initial letter.
514:             * @param name The name to test for JSON compatibility
515:             * @return true if the name is simple
516:             */
517:            public static boolean isSimpleName(String name) {
518:                if (name.length() == 0) {
519:                    return false;
520:                }
521:
522:                if (JavascriptUtil.isReservedWord(name)) {
523:                    return false;
524:                }
525:
526:                boolean isSimple = Character.isLetter(name.charAt(0));
527:                for (int i = 1; isSimple && i < name.length(); i++) {
528:                    if (!Character.isLetterOrDigit(name.charAt(i))) {
529:                        isSimple = false;
530:                    }
531:                }
532:
533:                return isSimple;
534:            }
535:
536:            /**
537:             * Utility to essentially do Class forName and allow configurable
538:             * Classloaders.
539:             * <p>The initial implementation makes use of the context classloader for
540:             * the current thread.
541:             * @param className The class to create
542:             * @return The class if it is safe or null otherwise.
543:             * @throws ClassNotFoundException If <code>className</code> is not valid
544:             */
545:            public static Class<?> classForName(String className)
546:                    throws ClassNotFoundException {
547:                // Class.forName(className);
548:                return Thread.currentThread().getContextClassLoader()
549:                        .loadClass(className);
550:            }
551:
552:            /**
553:             * Calling methods using reflection is useful for graceful fallback - this
554:             * is a helper method to make this easy
555:             * @param object The object to use as 'this'
556:             * @param method The method to call, can be null in which case null is returned
557:             * @param params The parameters to pass to the reflection call
558:             * @return The results of calling method.invoke() or null
559:             * @throws IllegalStateException If anything goes wrong
560:             */
561:            public static Object invoke(Object object, Method method,
562:                    Object[] params) throws IllegalStateException {
563:                Object reply = null;
564:                if (method != null) {
565:                    try {
566:                        reply = method.invoke(object, params);
567:                    } catch (InvocationTargetException ex) {
568:                        throw new IllegalStateException(
569:                                "InvocationTargetException calling "
570:                                        + method.getName() + ": "
571:                                        + ex.getTargetException().toString());
572:                    } catch (Exception ex) {
573:                        throw new IllegalStateException(
574:                                "Reflection error calling " + method.getName()
575:                                        + ": " + ex.toString());
576:                    }
577:                }
578:
579:                return reply;
580:            }
581:
582:            /**
583:             * Utility to essentially do Class forName with the assumption that the
584:             * environment expects failures for missing jar files and can carry on if
585:             * this process fails.
586:             * @param <T> The base type that we want a class to implement
587:             * @param debugContext The name for debugging purposes
588:             * @param className The class to create
589:             * @param impl The implementation class - what should className do?
590:             * @return The class if it is safe or null otherwise.
591:             */
592:            @SuppressWarnings("unchecked")
593:            public static <T> Class<? extends T> classForName(
594:                    String debugContext, String className, Class<T> impl) {
595:                Class<? extends T> clazz;
596:
597:                try {
598:                    clazz = (Class<? extends T>) classForName(className);
599:                } catch (ClassNotFoundException ex) {
600:                    // We expect this sometimes, hence debug
601:                    log.debug("Skipping '" + debugContext
602:                            + "' due to ClassNotFoundException on " + className
603:                            + ". Cause: " + ex.getMessage());
604:                    return null;
605:                } catch (NoClassDefFoundError ex) {
606:                    // We expect this sometimes, hence debug
607:                    log.debug("Skipping '" + debugContext
608:                            + "' due to NoClassDefFoundError on " + className
609:                            + ". Cause: " + ex.getMessage());
610:                    return null;
611:                } catch (TransformerFactoryConfigurationError ex) {
612:                    // We expect this sometimes, hence debug
613:                    log
614:                            .debug("Skipping '"
615:                                    + debugContext
616:                                    + "' due to TransformerFactoryConfigurationError on "
617:                                    + className + ". Cause: " + ex.getMessage());
618:                    log
619:                            .debug("Maybe you need to add xalan.jar to your webserver?");
620:                    return null;
621:                }
622:
623:                // Check it is of the right type
624:                if (!impl.isAssignableFrom(clazz)) {
625:                    log.error("Class '" + clazz.getName()
626:                            + "' does not implement '" + impl.getName() + "'.");
627:                    return null;
628:                }
629:
630:                // Check we can create it
631:                try {
632:                    clazz.newInstance();
633:                } catch (InstantiationException ex) {
634:                    log.error("InstantiationException for '" + debugContext
635:                            + "' failed:", ex);
636:                    return null;
637:                } catch (IllegalAccessException ex) {
638:                    log.error("IllegalAccessException for '" + debugContext
639:                            + "' failed:", ex);
640:                    return null;
641:                } catch (NoClassDefFoundError ex) {
642:                    // We expect this sometimes, hence debug
643:                    log.debug("Skipping '" + debugContext
644:                            + "' due to NoClassDefFoundError on " + className
645:                            + ". Cause: " + ex.getMessage());
646:                    return null;
647:                } catch (TransformerFactoryConfigurationError ex) {
648:                    // We expect this sometimes, hence debug
649:                    log
650:                            .debug("Skipping '"
651:                                    + debugContext
652:                                    + "' due to TransformerFactoryConfigurationError on "
653:                                    + className + ". Cause: " + ex.getMessage());
654:                    log
655:                            .debug("Maybe you need to add xalan.jar to your webserver?");
656:                    return null;
657:                } catch (Exception ex) {
658:                    // For some reason we can't catch this?
659:                    if (ex instanceof  ClassNotFoundException) {
660:                        // We expect this sometimes, hence debug
661:                        log.debug("Skipping '" + debugContext
662:                                + "' due to ClassNotFoundException on "
663:                                + className + ". Cause: " + ex.getMessage());
664:                        return null;
665:                    } else {
666:                        log.error("Failed to load '" + debugContext + "' ("
667:                                + className + ")", ex);
668:                        return null;
669:                    }
670:                }
671:
672:                return clazz;
673:            }
674:
675:            /**
676:             * Utility to essentially do Class forName and newInstance with the
677:             * assumption that the environment expects failures for missing jar files
678:             * and can carry on if this process fails.
679:             * @param <T> The base type that we want a class to implement
680:             * @param name The name for debugging purposes
681:             * @param className The class to create
682:             * @param impl The implementation class - what should className do?
683:             * @return The new instance if it is safe or null otherwise.
684:             */
685:            @SuppressWarnings("unchecked")
686:            public static <T> T classNewInstance(String name, String className,
687:                    Class<T> impl) {
688:                Class<T> clazz;
689:
690:                try {
691:                    clazz = (Class<T>) classForName(className);
692:                } catch (ClassNotFoundException ex) {
693:                    // We expect this sometimes, hence debug
694:                    log.debug("Skipping '" + name
695:                            + "' due to ClassNotFoundException on " + className
696:                            + ". Cause: " + ex.getMessage());
697:                    return null;
698:                } catch (NoClassDefFoundError ex) {
699:                    // We expect this sometimes, hence debug
700:                    log.debug("Skipping '" + name
701:                            + "' due to NoClassDefFoundError on " + className
702:                            + ". Cause: " + ex.getMessage());
703:                    return null;
704:                } catch (TransformerFactoryConfigurationError ex) {
705:                    // We expect this sometimes, hence debug
706:                    log
707:                            .debug("Skipping '"
708:                                    + name
709:                                    + "' due to TransformerFactoryConfigurationError on "
710:                                    + className + ". Cause: " + ex.getMessage());
711:                    return null;
712:                }
713:
714:                // Check it is of the right type
715:                if (!impl.isAssignableFrom(clazz)) {
716:                    log.error("Class '" + clazz.getName()
717:                            + "' does not implement '" + impl.getName() + "'.");
718:                    return null;
719:                }
720:
721:                // Check we can create it
722:                try {
723:                    return clazz.newInstance();
724:                } catch (InstantiationException ex) {
725:                    log.error("InstantiationException for '" + name
726:                            + "' failed:", ex);
727:                    return null;
728:                } catch (IllegalAccessException ex) {
729:                    log.error("IllegalAccessException for '" + name
730:                            + "' failed:", ex);
731:                    return null;
732:                } catch (TransformerFactoryConfigurationError ex) {
733:                    log.error("TransformerFactoryConfigurationError for '"
734:                            + name + "' failed:", ex);
735:                    return null;
736:                } catch (Exception ex) {
737:                    log.error("Failed to load creator '" + name
738:                            + "', classname=" + className + ": ", ex);
739:                    return null;
740:                }
741:            }
742:
743:            /**
744:             * InputStream closer that can cope if the input stream is null.
745:             * If anything goes wrong, the errors are logged and ignored.
746:             * @param in The resource to close
747:             */
748:            public static void close(Closeable in) {
749:                if (in == null) {
750:                    return;
751:                }
752:
753:                try {
754:                    in.close();
755:                } catch (IOException ex) {
756:                    log.warn(ex.getMessage(), ex);
757:                }
758:            }
759:
760:            /**
761:             * Return a List of super-classes for the given class.
762:             * @param clazz the class to look up
763:             * @return the List of super-classes in order going up from this one
764:             */
765:            public static List<Class<?>> getAllSuperclasses(Class<?> clazz) {
766:                List<Class<?>> classes = new ArrayList<Class<?>>();
767:
768:                Class<?> super class = clazz.getSuperclass();
769:                while (super class != null) {
770:                    classes.add(super class);
771:                    super class = super class.getSuperclass();
772:                }
773:
774:                return classes;
775:            }
776:
777:            /**
778:             * Return a list of all fields (whatever access status, and on whatever
779:             * superclass they were defined) that can be found on this class.
780:             * <p>This is like a union of {@link Class#getDeclaredFields()} which
781:             * ignores and super-classes, and {@link Class#getFields()} which ignored
782:             * non-public fields
783:             * @param clazz The class to introspect
784:             * @return The complete list of fields
785:             */
786:            public static Field[] getAllFields(Class<?> clazz) {
787:                List<Class<?>> classes = getAllSuperclasses(clazz);
788:                classes.add(clazz);
789:                return getAllFields(classes);
790:            }
791:
792:            /**
793:             * As {@link #getAllFields(Class)} but acts on a list of {@link Class}s and
794:             * uses only {@link Class#getDeclaredFields()}.
795:             * @param classes The list of classes to reflect on
796:             * @return The complete list of fields
797:             */
798:            private static Field[] getAllFields(List<Class<?>> classes) {
799:                Set<Field> fields = new HashSet<Field>();
800:                for (Class<?> clazz : classes) {
801:                    fields.addAll(Arrays.asList(clazz.getDeclaredFields()));
802:                }
803:
804:                return fields.toArray(new Field[fields.size()]);
805:            }
806:
807:            /**
808:             * The log stream
809:             */
810:            private static final Log log = LogFactory.getLog(LocalUtil.class);
811:        }
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