/*
 * Copyright 1999,2005 The Apache Software Foundation.
 * 
 * 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,
 * 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 javax.servlet;


/**
 * Defines a general exception a servlet can throw when it
 * encounters difficulty.
 *
 * @author 	Various
 * @version 	$Version$
 *
 */


public class ServletException extends Exception {

    private Throwable rootCause;


    /**
     * Constructs a new servlet exception.
     *
     */

    public ServletException() {
	super();
    }
    
   
    /**
     * Constructs a new servlet exception with the
     * specified message. The message can be written 
     * to the server log and/or displayed for the user. 
     *
     * @param message 		a <code>String</code> 
     *				specifying the text of 
     *				the exception message
     *
     */

    public ServletException(String message) {
	super(message);
    }
    
   
    /**
     * Constructs a new servlet exception when the servlet 
     * needs to throw an exception and include a message 
     * about the "root cause" exception that interfered with its 
     * normal operation, including a description message.
     *
     *
     * @param message 		a <code>String</code> containing 
     *				the text of the exception message
     *
     * @param rootCause		the <code>Throwable</code> exception 
     *				that interfered with the servlet's
     *				normal operation, making this servlet
     *				exception necessary
     *
     */
    
    public ServletException(String message, Throwable rootCause) {
       super(message);
       this.rootCause = rootCause;
    }


    /**
     * Constructs a new servlet exception when the servlet 
     * needs to throw an exception and include a message
     * about the "root cause" exception that interfered with its
     * normal operation.  The exception's message is based on the localized
     * message of the underlying exception.
     *
     * <p>This method calls the <code>getLocalizedMessage</code> method
     * on the <code>Throwable</code> exception to get a localized exception
     * message. When subclassing <code>ServletException</code>, 
     * this method can be overridden to create an exception message 
     * designed for a specific locale.
     *
     * @param rootCause 	the <code>Throwable</code> exception
     * 				that interfered with the servlet's
     *				normal operation, making the servlet exception
     *				necessary
     *
     */

    public ServletException(Throwable rootCause) {
       super(rootCause.getLocalizedMessage());
       this.rootCause = rootCause;
    }
  
  
    /**
     * Returns the exception that caused this servlet exception.
     *
     *
     * @return			the <code>Throwable</code> 
     *				that caused this servlet exception
     *
     */
    
    public Throwable getRootCause() {
	return rootCause;
    }
}