javax.servlet.UnavailableException Maven / Gradle / Ivy
/**
*
* Copyright 2003-2004 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.
*/
//
// This source code implements specifications defined by the Java
// Community Process. In order to remain compliant with the specification
// DO NOT add / change / or delete method signatures!
//
package javax.servlet;
/**
* Defines an exception that a servlet or filter throws to indicate
* that it is permanently or temporarily unavailable.
*
* When a servlet or filter is permanently unavailable, something is wrong
* with it, and it cannot handle
* requests until some action is taken. For example, a servlet
* might be configured incorrectly, or a filter's state may be corrupted.
* The component should log both the error and the corrective action
* that is needed.
*
*
A servlet or filter is temporarily unavailable if it cannot handle
* requests momentarily due to some system-wide problem. For example,
* a third-tier server might not be accessible, or there may be
* insufficient memory or disk storage to handle requests. A system
* administrator may need to take corrective action.
*
*
Servlet containers can safely treat both types of unavailable
* exceptions in the same way. However, treating temporary unavailability
* effectively makes the servlet container more robust. Specifically,
* the servlet container might block requests to the servlet or filter for a period
* of time suggested by the exception, rather than rejecting them until
* the servlet container restarts.
*
* @version $Rev: 46019 $ $Date: 2004-09-14 04:56:06 -0500 (Tue, 14 Sep 2004) $
*/
public class UnavailableException extends ServletException {
/**
* What is unavailable
*/
private Servlet servlet;
/**
* Does this need an admin action?
*/
private boolean permanent;
/**
* Estimate of how long the resource will be unavaile.
*/
private int seconds;
/**
* @deprecated As of Java Servlet API 2.2, use {@link
* #UnavailableException(String)} instead.
*
* @param servlet the Servlet instance that is unavailable
*
* @param msg a String specifying the descriptive message
*/
public UnavailableException(Servlet servlet, String msg) {
super(msg);
this.servlet = servlet;
permanent = true;
}
/**
* @deprecated As of Java Servlet API 2.2, use {@link
* #UnavailableException(String, int)} instead.
*
* @param seconds an integer specifying the number of seconds
* the servlet expects to be unavailable; if zero or negative,
* indicates that the servlet can't make an estimate
*
* @param servlet the Servlet that is unavailable
*
* @param msg a String specifying the descriptive
* message, which can be written to a log file or displayed for
* the user.
*/
public UnavailableException(int seconds, Servlet servlet, String msg) {
super(msg);
this.servlet = servlet;
if (seconds <= 0) {
this.seconds = -1;
} else {
this.seconds = seconds;
}
permanent = false;
}
/**
* Constructs a new exception with a descriptive
* message indicating that the servlet is permanently
* unavailable.
*
* @param msg a String specifying the descriptive message
*/
public UnavailableException(String msg) {
super(msg);
permanent = true;
}
/**
* Constructs a new exception with a descriptive message
* indicating that the servlet is temporarily unavailable
* and giving an estimate of how long it will be unavailable.
*
*
In some cases, the servlet cannot make an estimate. For
* example, the servlet might know that a server it needs is
* not running, but not be able to report how long it will take
* to be restored to functionality. This can be indicated with
* a negative or zero value for the seconds argument.
*
* @param msg a String specifying the descriptive
* message, which can be written to a log file or displayed for
* the user.
*
* @param seconds an integer specifying the number of seconds
* the servlet expects to be unavailable; if zero or negative,
* indicates that the servlet can't make an estimate
*/
public UnavailableException(String msg, int seconds) {
super(msg);
if (seconds <= 0) {
this.seconds = -1;
} else {
this.seconds = seconds;
}
permanent = false;
}
/**
* Returns a boolean indicating
* whether the servlet is permanently unavailable.
* If so, something is wrong with the servlet, and the
* system administrator must take some corrective action.
*
* @return true if the servlet is
* permanently unavailable; false
* if the servlet is available or temporarily unavailable
*/
public boolean isPermanent() {
return permanent;
}
/**
* @deprecated As of Java Servlet API 2.2, with no replacement.
*
* Returns the servlet that is reporting its unavailability.
*
* @return the Servlet object that is
* throwing the UnavailableException
*/
public Servlet getServlet() {
return servlet;
}
/**
* Returns the number of seconds the servlet expects to
* be temporarily unavailable.
*
*
If this method returns a negative number, the servlet
* is permanently unavailable or cannot provide an estimate of
* how long it will be unavailable. No effort is
* made to correct for the time elapsed since the exception was
* first reported.
*
* @return an integer specifying the number of seconds
* the servlet will be temporarily unavailable, or a negative
* number if the servlet is permanently unavailable or cannot
* make an estimate
*/
public int getUnavailableSeconds() {
return permanent ? -1 : seconds;
}
}