Exception Helper : Exceptions « Language Basics « Java

Exception Helper

 * Copyright 2008-2010 the original author or authors 
 * Licensed 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,
 * See the License for the specific language governing permissions and
 * limitations under the License.
//package org.kaleidofoundry.core.util;

import java.io.PrintWriter;
import java.io.StringWriter;
import java.lang.reflect.Method;

 * Exception Helper
 * @author Jerome RADUGET
public abstract class ThrowableHelper {

  // Get javax.servlet.ServletException dynamically if no web container in
  // classpath (no need to have servlet.jar in classpath)
  final static Class<?> ServletExceptionClass;

  static {
    Class<?> servletExceptionClass = null;
    try {
      servletExceptionClass = Class
    } catch (final Throwable th) {
    ServletExceptionClass = servletExceptionClass;

   * @param th
   * @return the string representation of an exception stack trace
  public static String getStackTrace(final Throwable th) {

    final StringWriter writer = new StringWriter();
    final PrintWriter pw = new PrintWriter(writer);
    fillStackTrace(th, pw);

    return writer.toString();

   * @param ex
   * @param pw
  private static void fillStackTrace(final Throwable ex, final PrintWriter pw) {

    if (ex == null) {

    // exception stack trace

    // servlet exception root cause
    if (ServletExceptionClass != null
        && ex.getClass().isAssignableFrom(ServletExceptionClass)) {
      try {
        final Method getRootCauseMethod = ex.getClass().getMethod(
        final Throwable cause = (Throwable) getRootCauseMethod.invoke(
            ex, new Object[] {});
        if (null != cause) {
          pw.println("Root Cause:");
          fillStackTrace(cause, pw);
      } catch (final Throwable th) {

    // otherwise
    final Throwable cause = ex.getCause();
    if (null != cause) {
      fillStackTrace(cause, pw);



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