1 /**
2 * This file Copyright (c) 2009-2011 Magnolia International
3 * Ltd. (http://www.magnolia-cms.com). All rights reserved.
4 *
5 *
6 * This file is dual-licensed under both the Magnolia
7 * Network Agreement and the GNU General Public License.
8 * You may elect to use one or the other of these licenses.
9 *
10 * This file is distributed in the hope that it will be
11 * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
12 * implied warranty of MERCHANTABILITY or FITNESS FOR A
13 * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
14 * Redistribution, except as permitted by whichever of the GPL
15 * or MNA you select, is prohibited.
16 *
17 * 1. For the GPL license (GPL), you can redistribute and/or
18 * modify this file under the terms of the GNU General
19 * Public License, Version 3, as published by the Free Software
20 * Foundation. You should have received a copy of the GNU
21 * General Public License, Version 3 along with this program;
22 * if not, write to the Free Software Foundation, Inc., 51
23 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
24 *
25 * 2. For the Magnolia Network Agreement (MNA), this file
26 * and the accompanying materials are made available under the
27 * terms of the MNA which accompanies this distribution, and
28 * is available at http://www.magnolia-cms.com/mna.html
29 *
30 * Any modifications to this file must keep this entire header
31 * intact.
32 *
33 */
34 package info.magnolia.cms.util;
35
36 import org.apache.commons.lang.StringUtils;
37
38 /**
39 * Util to handle exceptions.
40 *
41 * @version $Revision: $ ($Author: $)
42 */
43 public class ExceptionUtil {
44
45 /**
46 * Given a RuntimeException, this method will:
47 * - throw its cause exception, if the cause exception is an instance of the type of the unwrapIf parameter
48 * - throw its cause exception, if the cause exception is a RuntimeException
49 * - throw the given RuntimeException otherwise.
50 */
51 public static <E extends Throwable> void unwrapIf(RuntimeException e, Class<E> unwrapIf) throws E {
52 final Throwable wrapped = e.getCause();
53 if (unwrapIf != null && unwrapIf.isInstance(wrapped)) {
54 throw (E) wrapped;
55 } else if (wrapped != null && wrapped instanceof RuntimeException) {
56 throw (RuntimeException) wrapped;
57 } else {
58 throw e;
59 }
60 }
61
62 /**
63 * This method helps palliating the absence of multi-catch (introduced in Java 7) - catch the lower common
64 * denominator exception and let this method do the rest - <strong>Use with great care!</strong>.
65 * <strong>Warning:</strong> this method can be abused, and would let one throw undeclared exceptions, which would
66 * in turn produce unexpected and undesirable effects on calling code. Just resist the urge to use this outside
67 * "multi-catch" scenarios.
68 */
69 @SuppressWarnings("unchecked")
70 public static void rethrow(Throwable e, Class<? extends Throwable>... allowedExceptions) {
71 if (RuntimeException.class.isInstance(e)) {
72 throw (RuntimeException) e;
73 }
74 for (Class<? extends Throwable> allowedException : allowedExceptions) {
75 if (allowedException.isInstance(e)) {
76 sneakyThrow(e);
77 }
78 }
79 throw new Error("Caught the following exception, which was not allowed: ", e);
80 }
81
82 /**
83 * Highly inspired by Lombok and the JavaPuzzlers, this method will let you throw a checked exception without declaring it.
84 * Use with GREAT care.
85 */
86 private static void sneakyThrow(Throwable t) {
87 ExceptionUtil.<RuntimeException>sneakyThrow_(t);
88 }
89
90 @SuppressWarnings("unchecked")
91 private static <T extends Throwable> void sneakyThrow_(Throwable t) throws T {
92 throw (T) t;
93 }
94
95 /**
96 * Returns true if the given exception or any of the nested cause exceptions is an instance of the <tt>suspectedCause</tt> exception argument, or a subclass thereof.
97 * This is equivalent to ExceptionUtils.indexOfThrowable(e, javax.jcr.AccessDeniedException.class) >= 0, only more readable, and possibly more performant.
98 */
99 public static boolean wasCausedBy(Throwable e, Class<? extends Throwable> suspectedCause) {
100 if (e != null && suspectedCause.isAssignableFrom(e.getClass())) {
101 return true;
102 } else if (e == null) {
103 return false;
104 } else {
105 return wasCausedBy(e.getCause(), suspectedCause);
106 }
107 }
108
109 /**
110 * Translates an exception class name to an english-readable idiom. Example: an instance of AccessDeniedException will be returned as "Access denied".
111 */
112 public static String classNameToWords(Exception e) {
113 return StringUtils.capitalize(StringUtils.removeEnd(e.getClass().getSimpleName(), "Exception").replaceAll("[A-Z]", " $0").toLowerCase().trim());
114 }
115
116 /**
117 * Translates an exception class name to an english-readable idiom, along with the exception's message.
118 * Example: an instance of AccessDeniedException("/foo/bar") will be returned as "Access denied: /foo/bar".
119 */
120 public static String exceptionToWords(Exception e) {
121 if (e.getMessage() != null) {
122 return classNameToWords(e) + ": " + e.getMessage();
123 } else {
124 return classNameToWords(e);
125 }
126 }
127 }