Source code: org/apache/http/util/ExceptionUtils.java
1 /*
2 * $HeadURL: https://svn.apache.org/repos/asf/jakarta/httpcomponents/httpcore/tags/4.0-alpha2/src/java/org/apache/http/util/ExceptionUtils.java $
3 * $Revision: 385120 $
4 * $Date: 2006-03-11 19:33:23 +0100 (Sat, 11 Mar 2006) $
5 *
6 * ====================================================================
7 *
8 * Copyright 1999-2006 The Apache Software Foundation
9 *
10 * Licensed under the Apache License, Version 2.0 (the "License");
11 * you may not use this file except in compliance with the License.
12 * You may obtain a copy of the License at
13 *
14 * http://www.apache.org/licenses/LICENSE-2.0
15 *
16 * Unless required by applicable law or agreed to in writing, software
17 * distributed under the License is distributed on an "AS IS" BASIS,
18 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
19 * See the License for the specific language governing permissions and
20 * limitations under the License.
21 * ====================================================================
22 *
23 * This software consists of voluntary contributions made by many
24 * individuals on behalf of the Apache Software Foundation. For more
25 * information on the Apache Software Foundation, please see
26 * <http://www.apache.org/>.
27 *
28 */
29 package org.apache.http.util;
30
31 import java.lang.reflect.Method;
32
33 /**
34 * The home for utility methods that handle various exception-related tasks.
35 *
36 * @author <a href="mailto:oleg at ural.ru">Oleg Kalnichevski</a>
37 * @author <a href="mailto:laura@lwerner.org">Laura Werner</a>
38 *
39 * @since 3.0
40 */
41 public class ExceptionUtils {
42
43 /** A reference to Throwable's initCause method, or null if it's not there in this JVM */
44 static private final Method INIT_CAUSE_METHOD = getInitCauseMethod();
45
46 /**
47 * Returns a <code>Method<code> allowing access to
48 * {@link Throwable.initCause(Throwable) initCause} method of {@link Throwable},
49 * or <code>null</code> if the method
50 * does not exist.
51 *
52 * @return A <code>Method<code> for <code>Throwable.initCause</code>, or
53 * <code>null</code> if unavailable.
54 */
55 static private Method getInitCauseMethod() {
56 try {
57 Class[] paramsClasses = new Class[] { Throwable.class };
58 return Throwable.class.getMethod("initCause", paramsClasses);
59 } catch (NoSuchMethodException e) {
60 return null;
61 }
62 }
63
64 /**
65 * If we're running on JDK 1.4 or later, initialize the cause for the given throwable.
66 *
67 * @param throwable The throwable.
68 * @param cause The cause of the throwable.
69 */
70 public static void initCause(Throwable throwable, Throwable cause) {
71 if (INIT_CAUSE_METHOD != null) {
72 try {
73 INIT_CAUSE_METHOD.invoke(throwable, new Object[] { cause });
74 } catch (Exception e) {
75 // Well, with no logging, the only option is to munch the exception
76 }
77 }
78 }
79
80 private ExceptionUtils() {
81 }
82
83 }