package org.ow2.easywsdl.u.exception;
import org.ow2.easywsdl.u.ArrayUtils;
import org.ow2.easywsdl.u.ClassUtils;
import org.ow2.easywsdl.u.StringUtils;
import org.ow2.easywsdl.u.SystemUtils;
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;
import java.util.StringTokenizer;
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;
}
/**
* Returns the given list as a <code>String[]</code>.
*
* @param list a list to transform.
* @return the given list as a <code>String[]</code>.
*/
private static String[] toArray(List list) {
return (String[]) list.toArray(new String[list.size()]);
}
//-----------------------------------------------------------------------
/**
* <p>Introspects the <code>Throwable</code> to obtain the cause.</p>
* <p/>
* <p>The method searches for methods with specific names that return a
* <code>Throwable</code> object. This will pick up most wrapping exceptions,
* including those from JDK 1.4, and
* {@link org.ow2.easywsdl.u.exception.NestableException NestableException}.
* <p/>
* <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/>
* <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/>
* <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) {
synchronized (CAUSE_METHOD_NAMES) {
return getCause(throwable, CAUSE_METHOD_NAMES);
}
}
/**
* <p>Introspects the <code>Throwable</code> to obtain the cause.</p>
* <p/>
* <ol>
* <li>Try known exception types.</li>
* <li>Try the supplied array of method names.</li>
* <li>Try the field 'detail'.</li>
* </ol>
* <p/>
* <p>A <code>null</code> set of method names means use the default set.
* A <code>null</code> in the set of method names will be ignored.</p>
*
* @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 <code>Throwable</code>,
* <code>null</code> 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) {
synchronized (CAUSE_METHOD_NAMES) {
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;
}
/**
* <p>Finds a <code>Throwable</code> for known types.</p>
* <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();
} else if (throwable instanceof InvocationTargetException) {
return ((InvocationTargetException) throwable).getTargetException();
} else {
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 = 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;
}
/**
* <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 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;
}
//-----------------------------------------------------------------------
/**
* <p>Checks if the Throwable class has a <code>getCause</code> method.</p>
* <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>Counts the number of <code>Throwable</code> objects in the
* exception chain.</p>
* <p/>
* <p>A throwable without cause will return <code>1</code>.
* A throwable with one cause will return <code>2</code> and so on.
* A <code>null</code> throwable will return <code>0</code>.</p>
* <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>
*
* @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();
}
/**
* <p>Returns the list of <code>Throwable</code> objects in the
* exception chain.</p>
* <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/>
* <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>
*
* @param throwable the throwable to inspect, may be null
* @return the array of throwables, never null
* @see #getThrowableList(Throwable)
*/
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/>
* <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/>
* <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>Returns the (zero based) index of the first <code>Throwable</code>
* that matches the specified class (exactly) in the exception chain.
* Subclasses of the specified class do not match - see
* <p/>
* <p>A <code>null</code> throwable returns <code>-1</code>.
* A <code>null</code> type returns <code>-1</code>.
* No match in the chain returns <code>-1</code>.</p>
*
* @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);
}
/**
* <p>Returns the (zero based) index of the first <code>Throwable</code>
* that matches the specified type in the exception chain from
* a specified index.
* Subclasses of the specified class do not match - see
* <p/>
* <p>A <code>null</code> throwable returns <code>-1</code>.
* A <code>null</code> type returns <code>-1</code>.
* No match in the chain returns <code>-1</code>.
* A negative start index is treated as zero.
* A start index greater than the number of throwables returns <code>-1</code>.</p>
*
* @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);
}
/**
* <p>Worker method for the <code>indexOfType</code> methods.</p>
*
* @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 <code>true</code>, compares with {@link Class#isAssignableFrom(Class)}, otherwise compares
* using references
* @return index of the <code>type</code> within throwables nested withing the specified <code>throwable</code>
*/
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;
}
/**
* <p>Removes common frames from the cause trace given the two stack traces.</p>
*
* @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--;
}
}
//-----------------------------------------------------------------------
/**
* <p>Returns an array where each element is a line from the argument.</p>
* <p/>
* <p>The end of line is determined by the value of {@link SystemUtils#LINE_SEPARATOR}.</p>
* <p/>
* <p>Functionality shared between the
* <code>getStackFrames(Throwable)</code> methods of this and the
* {@link org.ow2.easywsdl.u.exception.NestableDelegate} classes.</p>
*
* @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);
}
//-----------------------------------------------------------------------
/**
* Gets a short message summarising the exception.
* <p/>
* 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);
}
}