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/*
* 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.commons.lang.exception;
import java.io.PrintStream;
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.Arrays;
import java.util.List;
import java.util.StringTokenizer;
import org.apache.commons.lang.ArrayUtils;
import org.apache.commons.lang.ClassUtils;
import org.apache.commons.lang.NullArgumentException;
import org.apache.commons.lang.StringUtils;
import org.apache.commons.lang.SystemUtils;
/**
* Provides utilities for manipulating and examining
* Throwable objects.
*
* @author Daniel Rall
* @author Dmitri Plotnikov
* @author Stephen Colebourne
* @author Gary Gregory
* @author Pete Gieser
* @since 1.0
* @version $Id: ExceptionUtils.java 437554 2006-08-28 06:21:41Z bayard $
*/
public class ExceptionUtils {
/**
* Used when printing stack frames to denote the start of a
* wrapped exception.
*
* Package private for accessibility by test suite.
*/
static final String WRAPPED_MARKER = " [wrapped] ";
/**
* The names of methods commonly used to access a wrapped exception.
*/
private static String[] CAUSE_METHOD_NAMES = {
"getCause",
"getNextException",
"getTargetException",
"getException",
"getSourceException",
"getRootCause",
"getCausedByException",
"getNested",
"getLinkedException",
"getNestedException",
"getLinkedCause",
"getThrowable",
};
/**
* The Method object for Java 1.4 getCause.
*/
private static final Method THROWABLE_CAUSE_METHOD;
/**
* The Method object for Java 1.4 initCause.
*/
private static final Method THROWABLE_INITCAUSE_METHOD;
static {
Method causeMethod;
try {
causeMethod = Throwable.class.getMethod("getCause", null);
} catch (Exception e) {
causeMethod = null;
}
THROWABLE_CAUSE_METHOD = causeMethod;
try {
causeMethod = Throwable.class.getMethod("initCause", new Class[]{Throwable.class});
} catch (Exception e) {
causeMethod = null;
}
THROWABLE_INITCAUSE_METHOD = causeMethod;
}
/**
*
* Public constructor allows an instance of ExceptionUtils to be created, although that is not
* normally necessary.
*
*/
public ExceptionUtils() {
super();
}
//-----------------------------------------------------------------------
/**
* Adds to the list of method names used in the search for Throwable
* objects.
*
* @param methodName the methodName to add to the list, null
* and empty strings are ignored
* @since 2.0
*/
public static void addCauseMethodName(String methodName) {
if (StringUtils.isNotEmpty(methodName) && !isCauseMethodName(methodName)) {
List list = getCauseMethodNameList();
if (list.add(methodName)) {
CAUSE_METHOD_NAMES = toArray(list);
}
}
}
/**
* Removes from the list of method names used in the search for Throwable
* objects.
*
* @param methodName the methodName to remove from the list, null
* and empty strings are ignored
* @since 2.1
*/
public static void removeCauseMethodName(String methodName) {
if (StringUtils.isNotEmpty(methodName)) {
List list = getCauseMethodNameList();
if (list.remove(methodName)) {
CAUSE_METHOD_NAMES = toArray(list);
}
}
}
/**
* Sets the cause of a Throwable using introspection, allowing
* source code compatibility between pre-1.4 and post-1.4 Java releases.
*
* The typical use of this method is inside a constructor as in
* the following example:
*
*
* import org.apache.commons.lang.exception.ExceptionUtils;
*
* public class MyException extends Exception {
*
* public MyException(String msg) {
* super(msg);
* }
*
* public MyException(String msg, Throwable cause) {
* super(msg);
* ExceptionUtils.setCause(this, cause);
* }
* }
*
*
* @param target the target Throwable
* @param cause the Throwable to set in the target
* @return a true if the target has been modified
* @since 2.2
*/
public static boolean setCause(Throwable target, Throwable cause) {
if (target == null) {
throw new NullArgumentException("target");
}
Object[] causeArgs = new Object[]{cause};
boolean modifiedTarget = false;
if (THROWABLE_INITCAUSE_METHOD != null) {
try {
THROWABLE_INITCAUSE_METHOD.invoke(target, causeArgs);
modifiedTarget = true;
} catch (IllegalAccessException ignored) {
// Exception ignored.
} catch (InvocationTargetException ignored) {
// Exception ignored.
}
}
try {
Method setCauseMethod = target.getClass().getMethod("setCause", new Class[]{Throwable.class});
setCauseMethod.invoke(target, causeArgs);
modifiedTarget = true;
} catch (NoSuchMethodException ignored) {
// Exception ignored.
} catch (IllegalAccessException ignored) {
// Exception ignored.
} catch (InvocationTargetException ignored) {
// Exception ignored.
}
return modifiedTarget;
}
/**
* Returns the given list as a String[].
* @param list a list to transform.
* @return the given list as a String[].
*/
private static String[] toArray(List list) {
return (String[]) list.toArray(new String[list.size()]);
}
/**
* Returns {@link #CAUSE_METHOD_NAMES} as a List.
*
* @return {@link #CAUSE_METHOD_NAMES} as a List.
*/
private static ArrayList getCauseMethodNameList() {
return new ArrayList(Arrays.asList(CAUSE_METHOD_NAMES));
}
/**
* Tests if the list of method names used in the search for Throwable
* objects include the given name.
*
* @param methodName the methodName to search in the list.
* @return if the list of method names used in the search for Throwable
* objects include the given name.
* @since 2.1
*/
public static boolean isCauseMethodName(String methodName) {
return ArrayUtils.indexOf(CAUSE_METHOD_NAMES, methodName) >= 0;
}
//-----------------------------------------------------------------------
/**
* Introspects the Throwable to obtain the cause.
*
* The method searches for methods with specific names that return a
* Throwable object. This will pick up most wrapping exceptions,
* including those from JDK 1.4, and
* {@link org.apache.commons.lang.exception.NestableException NestableException}.
* The method names can be added to using {@link #addCauseMethodName(String)}.
*
* The default list searched for are:
*
* getCause()getNextException()getTargetException()getException()getSourceException()getRootCause()getCausedByException()getNested()
*
* In the absence of any such method, the object is inspected for a
* detail field assignable to a Throwable.
*
* If none of the above is found, returns null.
*
* @param throwable the throwable to introspect for a cause, may be null
* @return the cause of the Throwable,
* null if none found or null throwable input
* @since 1.0
*/
public static Throwable getCause(Throwable throwable) {
return getCause(throwable, CAUSE_METHOD_NAMES);
}
/**
* Introspects the Throwable to obtain the cause.
*
*
* - Try known exception types.
* - Try the supplied array of method names.
* - Try the field 'detail'.
*
*
* A null set of method names means use the default set.
* A null in the set of method names will be ignored.
*
* @param throwable the throwable to introspect for a cause, may be null
* @param methodNames the method names, null treated as default set
* @return the cause of the Throwable,
* null if none found or null throwable input
* @since 1.0
*/
public static Throwable getCause(Throwable throwable, String[] methodNames) {
if (throwable == null) {
return null;
}
Throwable cause = getCauseUsingWellKnownTypes(throwable);
if (cause == null) {
if (methodNames == null) {
methodNames = CAUSE_METHOD_NAMES;
}
for (int i = 0; i < methodNames.length; i++) {
String methodName = methodNames[i];
if (methodName != null) {
cause = getCauseUsingMethodName(throwable, methodName);
if (cause != null) {
break;
}
}
}
if (cause == null) {
cause = getCauseUsingFieldName(throwable, "detail");
}
}
return cause;
}
/**
* Introspects the Throwable to obtain the root cause.
*
* This method walks through the exception chain to the last element,
* "root" of the tree, using {@link #getCause(Throwable)}, and
* returns that exception.
*
* From version 2.2, this method handles recursive cause structures
* that might otherwise cause infinite loops. If the throwable parameter
* has a cause of itself, then null will be returned. If the throwable
* parameter cause chain loops, the last element in the chain before the
* loop is returned.
*
* @param throwable the throwable to get the root cause for, may be null
* @return the root cause of the Throwable,
* null if none found or null throwable input
*/
public static Throwable getRootCause(Throwable throwable) {
List list = getThrowableList(throwable);
return (list.size() < 2 ? null : (Throwable)list.get(list.size() - 1));
}
/**
* Finds a Throwable for known types.
*
* Uses instanceof checks to examine the exception,
* looking for well known types which could contain chained or
* wrapped exceptions.
*
* @param throwable the exception to examine
* @return the wrapped exception, or null 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();
} else if (throwable instanceof InvocationTargetException) {
return ((InvocationTargetException) throwable).getTargetException();
} else {
return null;
}
}
/**
* Finds a Throwable by method name.
*
* @param throwable the exception to examine
* @param methodName the name of the method to find and invoke
* @return the wrapped exception, or null if not found
*/
private static Throwable getCauseUsingMethodName(Throwable throwable, String methodName) {
Method method = null;
try {
method = throwable.getClass().getMethod(methodName, null);
} catch (NoSuchMethodException ignored) {
// exception ignored
} catch (SecurityException ignored) {
// exception ignored
}
if (method != null && Throwable.class.isAssignableFrom(method.getReturnType())) {
try {
return (Throwable) method.invoke(throwable, ArrayUtils.EMPTY_OBJECT_ARRAY);
} catch (IllegalAccessException ignored) {
// exception ignored
} catch (IllegalArgumentException ignored) {
// exception ignored
} catch (InvocationTargetException ignored) {
// exception ignored
}
}
return null;
}
/**
* Finds a Throwable by field name.
*
* @param throwable the exception to examine
* @param fieldName the name of the attribute to examine
* @return the wrapped exception, or null if not found
*/
private static Throwable getCauseUsingFieldName(Throwable throwable, String fieldName) {
Field field = null;
try {
field = throwable.getClass().getField(fieldName);
} catch (NoSuchFieldException ignored) {
// exception ignored
} catch (SecurityException ignored) {
// exception ignored
}
if (field != null && Throwable.class.isAssignableFrom(field.getType())) {
try {
return (Throwable) field.get(throwable);
} catch (IllegalAccessException ignored) {
// exception ignored
} catch (IllegalArgumentException ignored) {
// exception ignored
}
}
return null;
}
//-----------------------------------------------------------------------
/**
* Checks if the Throwable class has a getCause method.
*
* This is true for JDK 1.4 and above.
*
* @return true if Throwable is nestable
* @since 2.0
*/
public static boolean isThrowableNested() {
return THROWABLE_CAUSE_METHOD != null;
}
/**
* Checks whether this Throwable class can store a cause.
*
* This method does not check whether it actually does store a cause.
*
* @param throwable the Throwable to examine, may be null
* @return boolean true if nested otherwise false
* @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 (int i = 0, isize = CAUSE_METHOD_NAMES.length; i < isize; i++) {
try {
Method method = cls.getMethod(CAUSE_METHOD_NAMES[i], null);
if (method != null && Throwable.class.isAssignableFrom(method.getReturnType())) {
return true;
}
} catch (NoSuchMethodException ignored) {
// exception ignored
} catch (SecurityException ignored) {
// exception ignored
}
}
try {
Field field = cls.getField("detail");
if (field != null) {
return true;
}
} catch (NoSuchFieldException ignored) {
// exception ignored
} catch (SecurityException ignored) {
// exception ignored
}
return false;
}
//-----------------------------------------------------------------------
/**
*
Counts the number of Throwable objects in the
* exception chain.
*
* A throwable without cause will return 1.
* A throwable with one cause will return 2 and so on.
* A null throwable will return 0.
*
* 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.
*
* @param throwable the throwable to inspect, may be null
* @return the count of throwables, zero if null input
*/
public static int getThrowableCount(Throwable throwable) {
return getThrowableList(throwable).size();
}
/**
* Returns the list of Throwable objects in the
* exception chain.
*
* 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 null throwable will return an array of size zero.
*
* 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.
*
* @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()]);
}
/**
* Returns the list of Throwable objects in the
* exception chain.
*
* 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 null throwable will return a list of size zero.
*
* 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.
*
* @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;
}
//-----------------------------------------------------------------------
/**
* Returns the (zero based) index of the first Throwable
* that matches the specified class (exactly) in the exception chain.
* Subclasses of the specified class do not match - see
* {@link #indexOfType(Throwable, Class)} for the opposite.
*
* A null throwable returns -1.
* A null type returns -1.
* No match in the chain returns -1.
*
* @param throwable the throwable to inspect, may be null
* @param clazz the class to search for, subclasses do not match, null returns -1
* @return the index into the throwable chain, -1 if no match or null input
*/
public static int indexOfThrowable(Throwable throwable, Class clazz) {
return indexOf(throwable, clazz, 0, false);
}
/**
* Returns the (zero based) index of the first Throwable
* that matches the specified type in the exception chain from
* a specified index.
* Subclasses of the specified class do not match - see
* {@link #indexOfType(Throwable, Class, int)} for the opposite.
*
* A null throwable returns -1.
* A null type returns -1.
* No match in the chain returns -1.
* A negative start index is treated as zero.
* A start index greater than the number of throwables returns -1.
*
* @param throwable the throwable to inspect, may be null
* @param clazz the class to search for, subclasses do not match, null returns -1
* @param fromIndex the (zero based) index of the starting position,
* negative treated as zero, larger than chain size returns -1
* @return the index into the throwable chain, -1 if no match or null input
*/
public static int indexOfThrowable(Throwable throwable, Class clazz, int fromIndex) {
return indexOf(throwable, clazz, fromIndex, false);
}
//-----------------------------------------------------------------------
/**
* Returns the (zero based) index of the first Throwable
* that matches the specified class or subclass in the exception chain.
* Subclasses of the specified class do match - see
* {@link #indexOfThrowable(Throwable, Class)} for the opposite.
*
* A null throwable returns -1.
* A null type returns -1.
* No match in the chain returns -1.
*
* @param throwable the throwable to inspect, may be null
* @param type the type to search for, subclasses match, null returns -1
* @return the index into the throwable chain, -1 if no match or null input
* @since 2.1
*/
public static int indexOfType(Throwable throwable, Class type) {
return indexOf(throwable, type, 0, true);
}
/**
* Returns the (zero based) index of the first Throwable
* that matches the specified type in the exception chain from
* a specified index.
* Subclasses of the specified class do match - see
* {@link #indexOfThrowable(Throwable, Class)} for the opposite.
*
* A null throwable returns -1.
* A null type returns -1.
* No match in the chain returns -1.
* A negative start index is treated as zero.
* A start index greater than the number of throwables returns -1.
*
* @param throwable the throwable to inspect, may be null
* @param type the type to search for, subclasses match, null returns -1
* @param fromIndex the (zero based) index of the starting position,
* negative treated as zero, larger than chain size returns -1
* @return the index into the throwable chain, -1 if no match or null input
* @since 2.1
*/
public static int indexOfType(Throwable throwable, Class type, int fromIndex) {
return indexOf(throwable, type, fromIndex, true);
}
/**
* Worker method for the indexOfType methods.
*
* @param throwable the throwable to inspect, may be null
* @param type the type to search for, subclasses match, null returns -1
* @param fromIndex the (zero based) index of the starting position,
* negative treated as zero, larger than chain size returns -1
* @param subclass if true, compares with {@link Class#isAssignableFrom(Class)}, otherwise compares
* using references
* @return index of the type within throwables nested withing the specified throwable
*/
private static int indexOf(Throwable throwable, Class type, int fromIndex, boolean subclass) {
if (throwable == null || type == null) {
return -1;
}
if (fromIndex < 0) {
fromIndex = 0;
}
Throwable[] throwables = ExceptionUtils.getThrowables(throwable);
if (fromIndex >= throwables.length) {
return -1;
}
if (subclass) {
for (int i = fromIndex; i < throwables.length; i++) {
if (type.isAssignableFrom(throwables[i].getClass())) {
return i;
}
}
} else {
for (int i = fromIndex; i < throwables.length; i++) {
if (type.equals(throwables[i].getClass())) {
return i;
}
}
}
return -1;
}
//-----------------------------------------------------------------------
/**
* Prints a compact stack trace for the root cause of a throwable
* to System.err.
*
* The compact stack trace starts with the root cause and prints
* stack frames up to the place where it was caught and wrapped.
* Then it prints the wrapped exception and continues with stack frames
* until the wrapper exception is caught and wrapped again, etc.
*
* The output of this method is consistent across JDK versions.
* Note that this is the opposite order to the JDK1.4 display.
*
* The method is equivalent to printStackTrace for throwables
* that don't have nested causes.
*
* @param throwable the throwable to output
* @since 2.0
*/
public static void printRootCauseStackTrace(Throwable throwable) {
printRootCauseStackTrace(throwable, System.err);
}
/**
* Prints a compact stack trace for the root cause of a throwable.
*
* The compact stack trace starts with the root cause and prints
* stack frames up to the place where it was caught and wrapped.
* Then it prints the wrapped exception and continues with stack frames
* until the wrapper exception is caught and wrapped again, etc.
*
* The output of this method is consistent across JDK versions.
* Note that this is the opposite order to the JDK1.4 display.
*
* The method is equivalent to printStackTrace for throwables
* that don't have nested causes.
*
* @param throwable the throwable to output, may be null
* @param stream the stream to output to, may not be null
* @throws IllegalArgumentException if the stream is null
* @since 2.0
*/
public static void printRootCauseStackTrace(Throwable throwable, PrintStream stream) {
if (throwable == null) {
return;
}
if (stream == null) {
throw new IllegalArgumentException("The PrintStream must not be null");
}
String trace[] = getRootCauseStackTrace(throwable);
for (int i = 0; i < trace.length; i++) {
stream.println(trace[i]);
}
stream.flush();
}
/**
* Prints a compact stack trace for the root cause of a throwable.
*
* The compact stack trace starts with the root cause and prints
* stack frames up to the place where it was caught and wrapped.
* Then it prints the wrapped exception and continues with stack frames
* until the wrapper exception is caught and wrapped again, etc.
*
* The output of this method is consistent across JDK versions.
* Note that this is the opposite order to the JDK1.4 display.
*
* The method is equivalent to printStackTrace for throwables
* that don't have nested causes.
*
* @param throwable the throwable to output, may be null
* @param writer the writer to output to, may not be null
* @throws IllegalArgumentException if the writer is null
* @since 2.0
*/
public static void printRootCauseStackTrace(Throwable throwable, PrintWriter writer) {
if (throwable == null) {
return;
}
if (writer == null) {
throw new IllegalArgumentException("The PrintWriter must not be null");
}
String trace[] = getRootCauseStackTrace(throwable);
for (int i = 0; i < trace.length; i++) {
writer.println(trace[i]);
}
writer.flush();
}
//-----------------------------------------------------------------------
/**
* Creates a compact stack trace for the root cause of the supplied
* Throwable.
*
* The output of this method is consistent across JDK versions.
* It consists of the root exception followed by each of its wrapping
* exceptions separated by '[wrapped]'. Note that this is the opposite
* order to the JDK1.4 display.
*
* @param throwable the throwable to examine, may be null
* @return an array of stack trace frames, never null
* @since 2.0
*/
public static String[] getRootCauseStackTrace(Throwable throwable) {
if (throwable == null) {
return ArrayUtils.EMPTY_STRING_ARRAY;
}
Throwable throwables[] = getThrowables(throwable);
int count = throwables.length;
ArrayList frames = new ArrayList();
List nextTrace = getStackFrameList(throwables[count - 1]);
for (int i = count; --i >= 0;) {
List trace = nextTrace;
if (i != 0) {
nextTrace = getStackFrameList(throwables[i - 1]);
removeCommonFrames(trace, nextTrace);
}
if (i == count - 1) {
frames.add(throwables[i].toString());
} else {
frames.add(WRAPPED_MARKER + throwables[i].toString());
}
for (int j = 0; j < trace.size(); j++) {
frames.add(trace.get(j));
}
}
return (String[]) frames.toArray(new String[0]);
}
/**
* Removes common frames from the cause trace given the two stack traces.
*
* @param causeFrames stack trace of a cause throwable
* @param wrapperFrames stack trace of a wrapper throwable
* @throws IllegalArgumentException if either argument is null
* @since 2.0
*/
public static void removeCommonFrames(List causeFrames, List wrapperFrames) {
if (causeFrames == null || wrapperFrames == null) {
throw new IllegalArgumentException("The List must not be null");
}
int causeFrameIndex = causeFrames.size() - 1;
int wrapperFrameIndex = wrapperFrames.size() - 1;
while (causeFrameIndex >= 0 && wrapperFrameIndex >= 0) {
// Remove the frame from the cause trace if it is the same
// as in the wrapper trace
String causeFrame = (String) causeFrames.get(causeFrameIndex);
String wrapperFrame = (String) wrapperFrames.get(wrapperFrameIndex);
if (causeFrame.equals(wrapperFrame)) {
causeFrames.remove(causeFrameIndex);
}
causeFrameIndex--;
wrapperFrameIndex--;
}
}
//-----------------------------------------------------------------------
/**
* A way to get the entire nested stack-trace of an throwable.
*
* The result of this method is highly dependent on the JDK version
* and whether the exceptions override printStackTrace or not.
*
* @param throwable the Throwable 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();
}
//-----------------------------------------------------------------------
/**
* Gets the stack trace from a Throwable as a String.
*
* The result of this method vary by JDK version as this method
* uses {@link Throwable#printStackTrace(java.io.PrintWriter)}.
* On JDK1.3 and earlier, the cause exception will not be shown
* unless the specified throwable alters printStackTrace.
*
* @param throwable the Throwable to be examined
* @return the stack trace as generated by the exception's
* printStackTrace(PrintWriter) method
*/
public static String getStackTrace(Throwable throwable) {
StringWriter sw = new StringWriter();
PrintWriter pw = new PrintWriter(sw, true);
throwable.printStackTrace(pw);
return sw.getBuffer().toString();
}
/**
* Captures the stack trace associated with the specified
* Throwable object, decomposing it into a list of
* stack frames.
*
* The result of this method vary by JDK version as this method
* uses {@link Throwable#printStackTrace(java.io.PrintWriter)}.
* On JDK1.3 and earlier, the cause exception will not be shown
* unless the specified throwable alters printStackTrace.
*
* @param throwable the Throwable to examine, may be null
* @return an array of strings describing each stack frame, never null
*/
public static String[] getStackFrames(Throwable throwable) {
if (throwable == null) {
return ArrayUtils.EMPTY_STRING_ARRAY;
}
return getStackFrames(getStackTrace(throwable));
}
//-----------------------------------------------------------------------
/**
* Returns an array where each element is a line from the argument.
*
* The end of line is determined by the value of {@link SystemUtils#LINE_SEPARATOR}.
*
* Functionality shared between the
* getStackFrames(Throwable) methods of this and the
* {@link org.apache.commons.lang.exception.NestableDelegate} classes.
*
* @param stackTrace a stack trace String
* @return an array where each element is a line from the argument
*/
static String[] getStackFrames(String stackTrace) {
String linebreak = SystemUtils.LINE_SEPARATOR;
StringTokenizer frames = new StringTokenizer(stackTrace, linebreak);
List list = new ArrayList();
while (frames.hasMoreTokens()) {
list.add(frames.nextToken());
}
return toArray(list);
}
/**
* Produces a List of stack frames - the message
* is not included. Only the trace of the specified exception is
* returned, any caused by trace is stripped.
*
* This works in most cases - it will only fail if the exception
* message contains a line that starts with:
* " at".
*
* @param t is any throwable
* @return List of stack frames
*/
static List getStackFrameList(Throwable t) {
String stackTrace = getStackTrace(t);
String linebreak = SystemUtils.LINE_SEPARATOR;
StringTokenizer frames = new StringTokenizer(stackTrace, linebreak);
List list = new ArrayList();
boolean traceStarted = false;
while (frames.hasMoreTokens()) {
String token = frames.nextToken();
// Determine if the line starts with at
int at = token.indexOf("at");
if (at != -1 && token.substring(0, at).trim().length() == 0) {
traceStarted = true;
list.add(token);
} else if (traceStarted) {
break;
}
}
return list;
}
//-----------------------------------------------------------------------
/**
* Gets a short message summarising the exception.
*
* The message returned is of the form
* {ClassNameWithoutPackage}: {ThrowableMessage}
*
* @param th the throwable to get a message for, null returns empty string
* @return the message, non-null
* @since Commons Lang 2.2
*/
public static String getMessage(Throwable th) {
if (th == null) {
return "";
}
String clsName = ClassUtils.getShortClassName(th, null);
String msg = th.getMessage();
return clsName + ": " + StringUtils.defaultString(msg);
}
//-----------------------------------------------------------------------
/**
* Gets a short message summarising the root cause exception.
*
* The message returned is of the form
* {ClassNameWithoutPackage}: {ThrowableMessage}
*
* @param th the throwable to get a message for, null returns empty string
* @return the message, non-null
* @since Commons Lang 2.2
*/
public static String getRootCauseMessage(Throwable th) {
Throwable root = ExceptionUtils.getRootCause(th);
root = (root == null ? th : root);
return getMessage(root);
}
}