/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.isis.core.commons.exceptions;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
/**
* <p>Provides utilities for manipulating and examining
* <code>Throwable</code> objects.</p>
*
* @author Daniel L. Rall
* @author Dmitri Plotnikov
* @author Stephen Colebourne
* @author <a href="mailto:ggregory@seagullsw.com">Gary Gregory</a>
* @author Pete Gieser
* @since 1.0
* @version $Id: ExceptionUtils.java 594278 2007-11-12 19:58:30Z bayard $
*/
// portions copied in from commons-lang 2.6
public class ExceptionUtils {
/**
* <p>The names of methods commonly used to access a wrapped exception.</p>
*/
private static String[] CAUSE_METHOD_NAMES = {
"getCause",
"getNextException",
"getTargetException",
"getException",
"getSourceException",
"getRootCause",
"getCausedByException",
"getNested",
"getLinkedException",
"getNestedException",
"getLinkedCause",
"getThrowable",
};
/**
* <p>The Method object for Java 1.4 getCause.</p>
*/
private static final Method THROWABLE_CAUSE_METHOD;
static {
Method causeMethod;
try {
causeMethod = Throwable.class.getMethod("getCause", null);
} catch (Exception e) {
causeMethod = null;
}
THROWABLE_CAUSE_METHOD = causeMethod;
}
/**
* <p>
* Public constructor allows an instance of <code>ExceptionUtils</code> to be created, although that is not
* normally necessary.
* </p>
*/
public ExceptionUtils() {
super();
}
//-----------------------------------------------------------------------
/**
* <p>Introspects the <code>Throwable</code> to obtain the cause.</p>
*
* <p>The method searches for methods with specific names that return a
* <code>Throwable</code> object. This will pick up most wrapping exceptions.
*
* <p>The default list searched for are:</p>
* <ul>
* <li><code>getCause()</code></li>
* <li><code>getNextException()</code></li>
* <li><code>getTargetException()</code></li>
* <li><code>getException()</code></li>
* <li><code>getSourceException()</code></li>
* <li><code>getRootCause()</code></li>
* <li><code>getCausedByException()</code></li>
* <li><code>getNested()</code></li>
* </ul>
*
* <p>In the absence of any such method, the object is inspected for a
* <code>detail</code> field assignable to a <code>Throwable</code>.</p>
*
* <p>If none of the above is found, returns <code>null</code>.</p>
*
* @param throwable the throwable to introspect for a cause, may be null
* @return the cause of the <code>Throwable</code>,
* <code>null</code> if none found or null throwable input
* @since 1.0
*/
public static Throwable getCause(Throwable throwable) {
if (throwable == null) {
return null;
}
Throwable cause = getCauseUsingWellKnownTypes(throwable);
if (cause == null) {
for (String methodName : CAUSE_METHOD_NAMES) {
if (methodName != null) {
cause = getCauseUsingMethodName(throwable, methodName);
if (cause != null) {
break;
}
}
}
if (cause == null) {
cause = getCauseUsingFieldName(throwable, "detail");
}
}
return cause;
}
/**
* <p>Finds a <code>Throwable</code> for known types.</p>
*
* <p>Uses <code>instanceof</code> checks to examine the exception,
* looking for well known types which could contain chained or
* wrapped exceptions.</p>
*
* @param throwable the exception to examine
* @return the wrapped exception, or <code>null</code> if not found
*/
private static Throwable getCauseUsingWellKnownTypes(Throwable throwable) {
/*if (throwable instanceof Nestable) {
return ((Nestable) throwable).getCause();
} else */
if (throwable instanceof SQLException) {
return ((SQLException) throwable).getNextException();
}
if (throwable instanceof InvocationTargetException) {
return ((InvocationTargetException) throwable).getTargetException();
}
return null;
}
/**
* <p>Finds a <code>Throwable</code> by method name.</p>
*
* @param throwable the exception to examine
* @param methodName the name of the method to find and invoke
* @return the wrapped exception, or <code>null</code> if not found
*/
private static Throwable getCauseUsingMethodName(Throwable throwable, String methodName) {
Method method;
try {
method = throwable.getClass().getMethod(methodName);
} catch (NoSuchMethodException | SecurityException ignored) {
return null;
}
if (!Throwable.class.isAssignableFrom(method.getReturnType())) {
return null;
}
try {
return (Throwable) method.invoke(throwable);
} catch (IllegalAccessException | IllegalArgumentException | InvocationTargetException ignored) {
return null;
}
}
/**
* <p>Finds a <code>Throwable</code> by field name.</p>
*
* @param throwable the exception to examine
* @param fieldName the name of the attribute to examine
* @return the wrapped exception, or <code>null</code> if not found
*/
private static Throwable getCauseUsingFieldName(Throwable throwable, String fieldName) {
Field field = null;
try {
field = throwable.getClass().getField(fieldName);
} catch (NoSuchFieldException | SecurityException ignored) {
// exception ignored
}
if (field != null && Throwable.class.isAssignableFrom(field.getType())) {
try {
return (Throwable) field.get(throwable);
} catch (IllegalAccessException | IllegalArgumentException ignored) {
// exception ignored
}
}
return null;
}
/**
* <p>Checks if the Throwable class has a <code>getCause</code> method.</p>
*
* <p>This is true for JDK 1.4 and above.</p>
*
* @return true if Throwable is nestable
* @since 2.0
*/
public static boolean isThrowableNested() {
return THROWABLE_CAUSE_METHOD != null;
}
/**
* <p>Checks whether this <code>Throwable</code> class can store a cause.</p>
*
* <p>This method does <b>not</b> check whether it actually does store a cause.<p>
*
* @param throwable the <code>Throwable</code> to examine, may be null
* @return boolean <code>true</code> if nested otherwise <code>false</code>
* @since 2.0
*/
public static boolean isNestedThrowable(Throwable throwable) {
if (throwable == null) {
return false;
}
/*if (throwable instanceof Nestable) {
return true;
} else*/ if (throwable instanceof SQLException) {
return true;
} else if (throwable instanceof InvocationTargetException) {
return true;
} else if (isThrowableNested()) {
return true;
}
Class cls = throwable.getClass();
for (final String causeMethodName : CAUSE_METHOD_NAMES) {
try {
Method method = cls.getMethod(causeMethodName, null);
if (method != null && Throwable.class.isAssignableFrom(method.getReturnType())) {
return true;
}
} catch (NoSuchMethodException | SecurityException ignored) {
// exception ignored
}
}
try {
Field field = cls.getField("detail");
if (field != null) {
return true;
}
} catch (NoSuchFieldException | SecurityException ignored) {
// exception ignored
}
return false;
}
/**
* <p>Returns the list of <code>Throwable</code> objects in the
* exception chain.</p>
*
* <p>A throwable without cause will return an array containing
* one element - the input throwable.
* A throwable with one cause will return an array containing
* two elements. - the input throwable and the cause throwable.
* A <code>null</code> throwable will return an array of size zero.</p>
*
* <p>From version 2.2, this method handles recursive cause structures
* that might otherwise cause infinite loops. The cause chain is
* processed until the end is reached, or until the next item in the
* chain is already in the result set.</p>
*
* @see #getThrowableList(Throwable)
* @param throwable the throwable to inspect, may be null
* @return the array of throwables, never null
*/
public static Throwable[] getThrowables(Throwable throwable) {
List list = getThrowableList(throwable);
return (Throwable[]) list.toArray(new Throwable[list.size()]);
}
/**
* <p>Returns the list of <code>Throwable</code> objects in the
* exception chain.</p>
*
* <p>A throwable without cause will return a list containing
* one element - the input throwable.
* A throwable with one cause will return a list containing
* two elements. - the input throwable and the cause throwable.
* A <code>null</code> throwable will return a list of size zero.</p>
*
* <p>This method handles recursive cause structures that might
* otherwise cause infinite loops. The cause chain is processed until
* the end is reached, or until the next item in the chain is already
* in the result set.</p>
*
* @param throwable the throwable to inspect, may be null
* @return the list of throwables, never null
* @since Commons Lang 2.2
*/
public static List getThrowableList(Throwable throwable) {
List list = new ArrayList();
while (throwable != null && list.contains(throwable) == false) {
list.add(throwable);
throwable = ExceptionUtils.getCause(throwable);
}
return list;
}
//-----------------------------------------------------------------------
/**
* <p>A way to get the entire nested stack-trace of an throwable.</p>
*
* <p>The result of this method is highly dependent on the JDK version
* and whether the exceptions override printStackTrace or not.</p>
*
* @param throwable the <code>Throwable</code> to be examined
* @return the nested stack trace, with the root cause first
* @since 2.0
*/
public static String getFullStackTrace(Throwable throwable) {
StringWriter sw = new StringWriter();
PrintWriter pw = new PrintWriter(sw, true);
Throwable[] ts = getThrowables(throwable);
for (int i = 0; i < ts.length; i++) {
ts[i].printStackTrace(pw);
if (isNestedThrowable(ts[i])) {
break;
}
}
return sw.getBuffer().toString();
}
}