001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.camel.util;
018    
019    import java.io.Closeable;
020    import java.io.IOException;
021    import java.lang.annotation.Annotation;
022    import java.lang.reflect.InvocationTargetException;
023    import java.lang.reflect.Method;
024    import java.nio.charset.Charset;
025    import java.util.ArrayList;
026    import java.util.Collection;
027    import java.util.Iterator;
028    import java.util.List;
029    
030    import org.apache.camel.RuntimeCamelException;
031    import org.apache.camel.converter.ObjectConverter;
032    import org.apache.commons.logging.Log;
033    import org.apache.commons.logging.LogFactory;
034    
035    /**
036     * A number of useful helper methods for working with Objects
037     *
038     * @version $Revision: 41272 $
039     */
040    public final class ObjectHelper {
041        private static final transient Log LOG = LogFactory.getLog(ObjectHelper.class);
042    
043        /**
044         * Utility classes should not have a public constructor.
045         */
046        private ObjectHelper() {
047        }
048    
049        /**
050         * @deprecated use the equal method instead
051         *
052         * @see #equal(Object, Object)
053         */
054        public static boolean equals(Object a, Object b) {
055            return equal(a, b);
056        }
057    
058        /**
059         * A helper method for comparing objects for equality while handling nulls
060         */
061        public static boolean equal(Object a, Object b) {
062            if (a == b) {
063                return true;
064            }
065    
066            if (a instanceof byte[] && b instanceof byte[]) {
067                return equalByteArray((byte[]) a, (byte[]) b);
068            }
069    
070            return a != null && b != null && a.equals(b);
071        }
072    
073        /**
074         * A helper method for comparing byte arrays for equality while handling nulls
075         */
076        public static boolean equalByteArray(byte[] a, byte[] b) {
077            if (a == b) {
078                return true;
079            }
080    
081            // loop and compare each byte
082            if (a != null && b != null && a.length == b.length) {
083                for (int i = 0; i < a.length; i++) {
084                    if (a[i] != b[i]) {
085                        return false;
086                    }
087                }
088                // all bytes are equal
089                return true;
090            }
091    
092            return false;
093        }
094    
095        /**
096         * Returns true if the given object is equal to any of the expected value
097         */
098        public static boolean isEqualToAny(Object object, Object... values) {
099            for (Object value : values) {
100                if (equal(object, value)) {
101                    return true;
102                }
103            }
104            return false;
105        }
106    
107        /**
108         * A helper method for performing an ordered comparsion on the objects
109         * handling nulls and objects which do not handle sorting gracefully
110         */
111        public static int compare(Object a, Object b) {
112            if (a == b) {
113                return 0;
114            }
115            if (a == null) {
116                return -1;
117            }
118            if (b == null) {
119                return 1;
120            }
121            if (a instanceof Comparable) {
122                Comparable comparable = (Comparable)a;
123                return comparable.compareTo(b);
124            } else {
125                int answer = a.getClass().getName().compareTo(b.getClass().getName());
126                if (answer == 0) {
127                    answer = a.hashCode() - b.hashCode();
128                }
129                return answer;
130            }
131        }
132    
133        public static void notNull(Object value, String name) {
134            if (value == null) {
135                throw new IllegalArgumentException(name + " must be specified");
136            }
137        }
138    
139        public static String[] splitOnCharacter(String value, String needle, int count) {
140            String rc[] = new String[count];
141            rc[0] = value;
142            for (int i = 1; i < count; i++) {
143                String v = rc[i - 1];
144                int p = v.indexOf(needle);
145                if (p < 0) {
146                    return rc;
147                }
148                rc[i - 1] = v.substring(0, p);
149                rc[i] = v.substring(p + 1);
150            }
151            return rc;
152        }
153    
154        /**
155         * Removes any starting characters on the given text which match the given
156         * character
157         *
158         * @param text the string
159         * @param ch the initial characters to remove
160         * @return either the original string or the new substring
161         */
162        public static String removeStartingCharacters(String text, char ch) {
163            int idx = 0;
164            while (text.charAt(idx) == ch) {
165                idx++;
166            }
167            if (idx > 0) {
168                return text.substring(idx);
169            }
170            return text;
171        }
172    
173        public static String capitalize(String text) {
174            if (text == null) {
175                return null;
176            }
177            int length = text.length();
178            if (length == 0) {
179                return text;
180            }
181            String answer = text.substring(0, 1).toUpperCase();
182            if (length > 1) {
183                answer += text.substring(1, length);
184            }
185            return answer;
186        }
187    
188    
189        /**
190         * Returns true if the collection contains the specified value
191         */
192        public static boolean contains(Object collectionOrArray, Object value) {
193            if (collectionOrArray instanceof Collection) {
194                Collection collection = (Collection)collectionOrArray;
195                return collection.contains(value);
196            } else if (collectionOrArray instanceof String && value instanceof String) {
197                String str = (String) collectionOrArray;
198                String subStr = (String) value;
199                return str.contains(subStr);
200            } else {
201                Iterator iter = ObjectConverter.iterator(collectionOrArray);
202                while (iter.hasNext()) {
203                    if (equal(value, iter.next())) {
204                        return true;
205                    }
206                }
207                return false;
208            }
209        }
210    
211        /**
212         * Returns the predicate matching boolean on a {@link List} result set where
213         * if the first element is a boolean its value is used otherwise this method
214         * returns true if the collection is not empty
215         *
216         * @return <tt>true</tt> if the first element is a boolean and its value is true or
217         *          if the list is non empty
218         */
219        public static boolean matches(List list) {
220            if (!list.isEmpty()) {
221                Object value = list.get(0);
222                if (value instanceof Boolean) {
223                    Boolean flag = (Boolean)value;
224                    return flag.booleanValue();
225                } else {
226                    // lets assume non-empty results are true
227                    return true;
228                }
229            }
230            return false;
231        }
232    
233        public static boolean isNotNullAndNonEmpty(String text) {
234            return text != null && text.trim().length() > 0;
235        }
236    
237        public static boolean isNullOrBlank(String text) {
238            return text == null || text.trim().length() <= 0;
239        }
240    
241        /**
242         * A helper method to access a system property, catching any security
243         * exceptions
244         *
245         * @param name the name of the system property required
246         * @param defaultValue the default value to use if the property is not
247         *                available or a security exception prevents access
248         * @return the system property value or the default value if the property is
249         *         not available or security does not allow its access
250         */
251        public static String getSystemProperty(String name, String defaultValue) {
252            try {
253                return System.getProperty(name, defaultValue);
254            } catch (Exception e) {
255                if (LOG.isDebugEnabled()) {
256                    LOG.debug("Caught security exception accessing system property: " + name + ". Reason: " + e,
257                              e);
258                }
259                return defaultValue;
260            }
261        }
262    
263        /**
264         * Returns the type name of the given type or null if the type variable is
265         * null
266         */
267        public static String name(Class type) {
268            return type != null ? type.getName() : null;
269        }
270    
271        /**
272         * Returns the type name of the given value
273         */
274        public static String className(Object value) {
275            return name(value != null ? value.getClass() : null);
276        }
277    
278        /**
279         * Attempts to load the given class name using the thread context class
280         * loader or the class loader used to load this class
281         *
282         * @param name the name of the class to load
283         * @return the class or null if it could not be loaded
284         */
285        public static Class<?> loadClass(String name) {
286            return loadClass(name, ObjectHelper.class.getClassLoader());
287        }
288    
289        /**
290         * Attempts to load the given class name using the thread context class
291         * loader or the given class loader
292         *
293         * @param name the name of the class to load
294         * @param loader the class loader to use after the thread context class
295         *                loader
296         * @return the class or null if it could not be loaded
297         */
298        public static Class<?> loadClass(String name, ClassLoader loader) {
299            ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();
300            if (contextClassLoader != null) {
301                try {
302                    return contextClassLoader.loadClass(name);
303                } catch (ClassNotFoundException e) {
304                    try {
305                        return loader.loadClass(name);
306                    } catch (ClassNotFoundException e1) {
307                        LOG.debug("Could not find class: " + name + ". Reason: " + e);
308                    }
309                }
310            }
311            return null;
312        }
313    
314        /**
315         * A helper method to invoke a method via reflection and wrap any exceptions
316         * as {@link RuntimeCamelException} instances
317         *
318         * @param method the method to invoke
319         * @param instance the object instance (or null for static methods)
320         * @param parameters the parameters to the method
321         * @return the result of the method invocation
322         */
323        public static Object invokeMethod(Method method, Object instance, Object... parameters) {
324            try {
325                return method.invoke(instance, parameters);
326            } catch (IllegalAccessException e) {
327                throw new RuntimeCamelException(e);
328            } catch (InvocationTargetException e) {
329                throw new RuntimeCamelException(e.getCause());
330            }
331        }
332    
333        /**
334         * Returns a list of methods which are annotated with the given annotation
335         *
336         * @param type the type to reflect on
337         * @param annotationType the annotation type
338         * @return a list of the methods found
339         */
340        public static List<Method> findMethodsWithAnnotation(Class<?> type,
341                                                             Class<? extends Annotation> annotationType) {
342            List<Method> answer = new ArrayList<Method>();
343            do {
344                Method[] methods = type.getDeclaredMethods();
345                for (Method method : methods) {
346                    if (method.getAnnotation(annotationType) != null) {
347                        answer.add(method);
348                    }
349                }
350                type = type.getSuperclass();
351            } while (type != null);
352            return answer;
353        }
354    
355        /**
356         * Turns the given object arrays into a meaningful string
357         *
358         * @param objects an array of objects or null
359         * @return a meaningful string
360         */
361        public static String asString(Object[] objects) {
362            if (objects == null) {
363                return "null";
364            } else {
365                StringBuffer buffer = new StringBuffer("{");
366                int counter = 0;
367                for (Object object : objects) {
368                    if (counter++ > 0) {
369                        buffer.append(", ");
370                    }
371                    String text = (object == null) ? "null" : object.toString();
372                    buffer.append(text);
373                }
374                buffer.append("}");
375                return buffer.toString();
376            }
377        }
378    
379        /**
380         * Returns true if a class is assignable from another class like the
381         * {@link Class#isAssignableFrom(Class)} method but which also includes
382         * coercion between primitive types to deal with Java 5 primitive type
383         * wrapping
384         */
385        public static boolean isAssignableFrom(Class a, Class b) {
386            a = convertPrimitiveTypeToWrapperType(a);
387            b = convertPrimitiveTypeToWrapperType(b);
388            return a.isAssignableFrom(b);
389        }
390    
391        /**
392         * Converts primitive types such as int to its wrapper type like
393         * {@link Integer}
394         */
395        public static Class convertPrimitiveTypeToWrapperType(Class type) {
396            Class rc = type;
397            if (type.isPrimitive()) {
398                if (type == int.class) {
399                    rc = Integer.class;
400                } else if (type == long.class) {
401                    rc = Long.class;
402                } else if (type == double.class) {
403                    rc = Double.class;
404                } else if (type == float.class) {
405                    rc = Float.class;
406                } else if (type == short.class) {
407                    rc = Short.class;
408                } else if (type == byte.class) {
409                    rc = Byte.class;
410                // TODO: Why is boolean disabled
411    /*
412                } else if (type == boolean.class) {
413                    rc = Boolean.class;
414    */
415                }
416            }
417            return rc;
418        }
419    
420        /**
421         * Helper method to return the default character set name
422         */
423        public static String getDefaultCharacterSet() {
424            return Charset.defaultCharset().name();
425        }
426    
427        /**
428         * Returns the Java Bean property name of the given method, if it is a setter
429         */
430        public static String getPropertyName(Method method) {
431            String propertyName = method.getName();
432            if (propertyName.startsWith("set") && method.getParameterTypes().length == 1) {
433                propertyName = propertyName.substring(3, 4).toLowerCase() + propertyName.substring(4);
434            }
435            return propertyName;
436        }
437    
438        /**
439         * Returns true if the given collection of annotations matches the given type
440         */
441        public static boolean hasAnnotation(Annotation[] annotations, Class<?> type) {
442            for (Annotation annotation : annotations) {
443                if (type.isInstance(annotation)) {
444                    return true;
445                }
446            }
447            return false;
448        }
449    
450        /**
451         * Closes the given resource if it is available, logging any closing exceptions to the given log
452         *
453         * @param closeable the object to close
454         * @param name the name of the resource
455         * @param log the log to use when reporting closure warnings
456         */
457        public static void close(Closeable closeable, String name, Log log) {
458            if (closeable != null) {
459                try {
460                    closeable.close();
461                } catch (IOException e) {
462                    log.warn("Could not close " + name + ". Reason: " + e, e);
463                }
464            }
465        }
466    
467        /**
468         * Converts the given value to the required type or throw a meaningful exception
469         */
470        public static <T> T cast(Class<T> toType, Object value) {
471            if (toType == boolean.class) {
472                return (T)cast(Boolean.class, value);
473            } else if (toType.isPrimitive()) {
474                Class newType = convertPrimitiveTypeToWrapperType(toType);
475                if (newType != toType) {
476                    return (T)cast(newType, value);
477                }
478            }
479            try {
480                return toType.cast(value);
481            } catch (ClassCastException e) {
482                throw new IllegalArgumentException("Failed to convert: " + value + " to type: "
483                                                   + toType.getName() + " due to: " + e, e);
484            }
485        }
486    
487        /**
488         * A helper method to create a new instance of a type using the default constructor arguments.
489         */
490        public static <T> T newInstance(Class<T> type) {
491            try {
492                return type.newInstance();
493            } catch (InstantiationException e) {
494                throw new RuntimeCamelException(e.getCause());
495            } catch (IllegalAccessException e) {
496                throw new RuntimeCamelException(e);
497            }
498        }
499    
500        /**
501         * A helper method to create a new instance of a type using the default constructor arguments.
502         */
503        public static <T> T newInstance(Class<?> actualType, Class<T> expectedType) {
504            try {
505                Object value = actualType.newInstance();
506                return cast(expectedType, value);
507            } catch (InstantiationException e) {
508                throw new RuntimeCamelException(e.getCause());
509            } catch (IllegalAccessException e) {
510                throw new RuntimeCamelException(e);
511            }
512        }
513    
514        /**
515         * Returns true if the given name is a valid java identifier
516         */
517        public static boolean isJavaIdentifier(String name) {
518            if (name == null) {
519                return false;
520            }
521            int size = name.length();
522            if (size < 1) {
523                return false;
524            }
525            if (Character.isJavaIdentifierStart(name.charAt(0))) {
526                for (int i = 1; i < size; i++) {
527                    if (!Character.isJavaIdentifierPart(name.charAt(i))) {
528                        return false;
529                    }
530                }
531                return true;
532            }
533            return false;
534        }
535    
536        /**
537         * Returns the type of the given object or null if the value is null
538         */
539        public static Object type(Object bean) {
540            return bean != null ? bean.getClass() : null;
541        }
542    }