From 6053ce341fc1f6b4e3c5e2a56535d07fb2bc505d Mon Sep 17 00:00:00 2001 From: Daniel Rall Date: Tue, 13 Aug 2002 18:05:58 +0000 Subject: [PATCH] Added a utility for examining Throwable objects, as proposed by Costin and Henri Yandell . Comes complete with a full suite of tests for initial functionality. git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/lang/trunk@136961 13f79535-47bb-0310-9956-ffa450edef68 --- .../lang/exception/ExceptionUtils.java | 169 ++++++++++++++++++ .../lang/exception/ExceptionTestSuite.java | 1 + .../exception/ExceptionUtilsTestCase.java | 128 +++++++++++++ 3 files changed, 298 insertions(+) create mode 100644 src/java/org/apache/commons/lang/exception/ExceptionUtils.java create mode 100644 src/test/org/apache/commons/lang/exception/ExceptionUtilsTestCase.java diff --git a/src/java/org/apache/commons/lang/exception/ExceptionUtils.java b/src/java/org/apache/commons/lang/exception/ExceptionUtils.java new file mode 100644 index 000000000..967833c36 --- /dev/null +++ b/src/java/org/apache/commons/lang/exception/ExceptionUtils.java @@ -0,0 +1,169 @@ +package org.apache.commons.lang.exception; + +/* ==================================================================== + * The Apache Software License, Version 1.1 + * + * Copyright (c) 2002 The Apache Software Foundation. All rights + * reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * + * 3. The end-user documentation included with the redistribution, if + * any, must include the following acknowlegement: + * "This product includes software developed by the + * Apache Software Foundation (http://www.apache.org/)." + * Alternately, this acknowlegement may appear in the software itself, + * if and wherever such third-party acknowlegements normally appear. + * + * 4. The names "The Jakarta Project", "Commons", and "Apache Software + * Foundation" must not be used to endorse or promote products derived + * from this software without prior written permission. For written + * permission, please contact apache@apache.org. + * + * 5. Products derived from this software may not be called "Apache" + * nor may "Apache" appear in their names without prior written + * permission of the Apache Software Foundation. + * + * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED + * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE + * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR + * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF + * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, + * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT + * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * ==================================================================== + * + * This software consists of voluntary contributions made by many + * individuals on behalf of the Apache Software Foundation. For more + * information on the Apache Software Foundation, please see + * . + */ + +import java.lang.reflect.InvocationTargetException; +import java.lang.reflect.Method; + +/** + * Utility routines for manipulating Throwable objects. + * + * @author Daniel Rall + * @since 1.0 + */ +public class ExceptionUtils +{ + /** + * The name of the getCause() method. + */ + protected static final String CAUSE_METHOD_NAME = "getCause"; + + /** + * The parameters of the getCause() method. + */ + protected static final Object[] CAUSE_METHOD_PARAMS = {}; + + /** + * Constructs a new ExceptionUtils. Protected to + * discourage instantiation. + */ + protected ExceptionUtils() + { + } + + /** + * Introspects the specified Throwable for a + * getCause() method (standard as of JDK 1.4, and + * part of the {@link + * org.apache.commons.lang.exception.NestableException} API), + * extracting and returning the cause of the exception. + * Otherwise, returns null. + *

+ * TODO: Examine for a "detail" public member attribute from + * java.rmi.RemoteException. + * + * @param t The exception to introspect for a cause. + * @return The cause of the Throwable. + */ + public static Throwable getCause(Throwable t) + { + Throwable cause = null; + + if (t instanceof NestableException) + { + cause = ((NestableException) t).getCause(); + } + else if (t instanceof NestableRuntimeException) + { + cause = ((NestableRuntimeException) t).getCause(); + } + else + { + Method getCause = null; + Class c = t.getClass(); + try + { + getCause = c.getMethod(CAUSE_METHOD_NAME, null); + } + catch (NoSuchMethodException ignored) + { + } + catch (SecurityException ignored) + { + } + + if (getCause != null && getCause.getReturnType() == Throwable.class) + { + try + { + cause = (Throwable) getCause.invoke(t, CAUSE_METHOD_PARAMS); + } + catch (IllegalAccessException ignored) + { + } + catch (IllegalArgumentException ignored) + { + } + catch (InvocationTargetException ignored) + { + } + } + } + + return cause; + } + + /** + * Walks through the exception chain to the last element -- the + * "root" of the tree -- using {@link #getCause(Throwable)}, and + * returns that exception. + * + * @return The root cause of the Throwable. + * @see #getCause(Throwable) + */ + public static Throwable getRootCause(Throwable t) + { + Throwable cause = getCause(t); + if (cause != null) + { + t = cause; + while ((t = getCause(t)) != null) + { + cause = t; + } + } + return cause; + } +} diff --git a/src/test/org/apache/commons/lang/exception/ExceptionTestSuite.java b/src/test/org/apache/commons/lang/exception/ExceptionTestSuite.java index 56ceaa8a6..294172a3a 100644 --- a/src/test/org/apache/commons/lang/exception/ExceptionTestSuite.java +++ b/src/test/org/apache/commons/lang/exception/ExceptionTestSuite.java @@ -88,6 +88,7 @@ public static Test suite() suite.addTest(NestableDelegateTestCase.suite()); suite.addTest(NestableExceptionTestCase.suite()); suite.addTest(NestableRuntimeExceptionTestCase.suite()); + suite.addTest(ExceptionUtilsTestCase.suite()); return suite; } } diff --git a/src/test/org/apache/commons/lang/exception/ExceptionUtilsTestCase.java b/src/test/org/apache/commons/lang/exception/ExceptionUtilsTestCase.java new file mode 100644 index 000000000..4dcff4156 --- /dev/null +++ b/src/test/org/apache/commons/lang/exception/ExceptionUtilsTestCase.java @@ -0,0 +1,128 @@ +package org.apache.commons.lang.exception; + +/* ==================================================================== + * The Apache Software License, Version 1.1 + * + * Copyright (c) 2002 The Apache Software Foundation. All rights + * reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * + * 3. The end-user documentation included with the redistribution, if + * any, must include the following acknowlegement: + * "This product includes software developed by the + * Apache Software Foundation (http://www.apache.org/)." + * Alternately, this acknowlegement may appear in the software itself, + * if and wherever such third-party acknowlegements normally appear. + * + * 4. The names "The Jakarta Project", "Commons", and "Apache Software + * Foundation" must not be used to endorse or promote products derived + * from this software without prior written permission. For written + * permission, please contact apache@apache.org. + * + * 5. Products derived from this software may not be called "Apache" + * nor may "Apache" appear in their names without prior written + * permission of the Apache Software Foundation. + * + * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED + * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE + * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR + * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF + * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, + * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT + * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * ==================================================================== + * + * This software consists of voluntary contributions made by many + * individuals on behalf of the Apache Software Foundation. For more + * information on the Apache Software Foundation, please see + * . + */ + +import junit.framework.Test; +import junit.framework.TestCase; +import junit.framework.TestSuite; + +/** + * Tests {@link org.apache.commons.lang.exception.ExceptionUtils}. + * + * @author Daniel Rall + * @since 1.0 + */ +public class ExceptionUtilsTestCase extends junit.framework.TestCase +{ + private NestableException nested; + private Throwable withCause; + private Throwable withoutCause; + + public ExceptionUtilsTestCase(String name) + { + super(name); + } + + public static Test suite() + { + return new TestSuite(ExceptionUtilsTestCase.class); + } + + public void setUp() + { + withoutCause = new ExceptionWithoutCause(); + nested = new NestableException(withoutCause); + withCause = new ExceptionWithCause(nested); + } + + public void testGetCause() + { + assertNull(ExceptionUtils.getCause(withoutCause)); + assertTrue(ExceptionUtils.getCause(nested) == withoutCause); + assertTrue(ExceptionUtils.getCause(withCause) == nested); + } + + public void testGetRootCause() + { + assertNull(ExceptionUtils.getRootCause(withoutCause)); + assertTrue(ExceptionUtils.getRootCause(withCause) == withoutCause); + assertTrue(ExceptionUtils.getRootCause(withCause) == withoutCause); + } + + private static class ExceptionWithCause extends Exception + { + private Throwable cause; + + public ExceptionWithCause(Throwable cause) + { + this.cause = cause; + } + + public Throwable getCause() + { + return cause; + } + } + + private static class ExceptionWithoutCause extends Exception + { + /** + * Bogus signature. + */ + public void getCause() + { + } + } +}