1 /* 2 * $HeadURL: http://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk/module-main/src/main/java/org/apache/http/util/ExceptionUtils.java $ 3 * $Revision: 613003 $ 4 * $Date: 2008-01-17 15:00:42 -0800 (Thu, 17 Jan 2008) $ 5 * 6 * ==================================================================== 7 * Licensed to the Apache Software Foundation (ASF) under one 8 * or more contributor license agreements. See the NOTICE file 9 * distributed with this work for additional information 10 * regarding copyright ownership. The ASF licenses this file 11 * to you under the Apache License, Version 2.0 (the 12 * "License"); you may not use this file except in compliance 13 * with the License. You may obtain a copy of the License at 14 * 15 * http://www.apache.org/licenses/LICENSE-2.0 16 * 17 * Unless required by applicable law or agreed to in writing, 18 * software distributed under the License is distributed on an 19 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 20 * KIND, either express or implied. See the License for the 21 * specific language governing permissions and limitations 22 * under the License. 23 * ==================================================================== 24 * 25 * This software consists of voluntary contributions made by many 26 * individuals on behalf of the Apache Software Foundation. For more 27 * information on the Apache Software Foundation, please see 28 * <http://www.apache.org/>. 29 * 30 */ 31 package org.apache.http.util; 32 33 import java.lang.reflect.Method; 34 35 /** 36 * The home for utility methods that handle various exception-related tasks. 37 * 38 * @author <a href="mailto:oleg at ural.ru">Oleg Kalnichevski</a> 39 * @author <a href="mailto:laura@lwerner.org">Laura Werner</a> 40 * 41 * @since 4.0 42 */ 43 public final class ExceptionUtils { 44 45 /** A reference to Throwable's initCause method, or null if it's not there in this JVM */ 46 static private final Method INIT_CAUSE_METHOD = getInitCauseMethod(); 47 48 /** 49 * Returns a <code>Method<code> allowing access to 50 * {@link Throwable#initCause(Throwable) initCause} method of {@link Throwable}, 51 * or <code>null</code> if the method 52 * does not exist. 53 * 54 * @return A <code>Method<code> for <code>Throwable.initCause</code>, or 55 * <code>null</code> if unavailable. 56 */ getInitCauseMethod()57 static private Method getInitCauseMethod() { 58 try { 59 Class[] paramsClasses = new Class[] { Throwable.class }; 60 return Throwable.class.getMethod("initCause", paramsClasses); 61 } catch (NoSuchMethodException e) { 62 return null; 63 } 64 } 65 66 /** 67 * If we're running on JDK 1.4 or later, initialize the cause for the given throwable. 68 * 69 * @param throwable The throwable. 70 * @param cause The cause of the throwable. 71 */ initCause(Throwable throwable, Throwable cause)72 public static void initCause(Throwable throwable, Throwable cause) { 73 if (INIT_CAUSE_METHOD != null) { 74 try { 75 INIT_CAUSE_METHOD.invoke(throwable, new Object[] { cause }); 76 } catch (Exception e) { 77 // Well, with no logging, the only option is to munch the exception 78 } 79 } 80 } 81 ExceptionUtils()82 private ExceptionUtils() { 83 } 84 85 } 86