| /* |
| * 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 javax.servlet; |
| |
| /** |
| * Defines an exception that a servlet or filter throws to indicate |
| * that it is permanently or temporarily unavailable. |
| * <p/> |
| * <p>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. |
| * <p/> |
| * <p>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. |
| * <p/> |
| * <p>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 $Rev$ $Date$ |
| */ |
| |
| public class UnavailableException extends ServletException { |
| |
| private final Servlet servlet; // what's unavailable |
| private final boolean permanent; // needs admin action? |
| private final int seconds; // unavailability estimate |
| |
| /** |
| * @param servlet the <code>Servlet</code> instance that is |
| * unavailable |
| * @param msg a <code>String</code> specifying the |
| * descriptive message |
| * @deprecated As of Java Servlet API 2.2, use {@link |
| * #UnavailableException(String)} instead. |
| */ |
| public UnavailableException(Servlet servlet, String msg) { |
| super(msg); |
| this.servlet = servlet; |
| permanent = true; |
| seconds = -1; |
| } |
| |
| /** |
| * @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 <code>Servlet</code> that is unavailable |
| * @param msg a <code>String</code> specifying the descriptive |
| * message, which can be written to a log file or |
| * displayed for the user. |
| * @deprecated As of Java Servlet API 2.2, use {@link |
| * #UnavailableException(String, int)} instead. |
| */ |
| 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 <code>String</code> specifying the |
| * descriptive message |
| */ |
| public UnavailableException(String msg) { |
| super(msg); |
| servlet = null; |
| permanent = true; |
| seconds = -1; |
| } |
| |
| /** |
| * 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. |
| * <p/> |
| * <p>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 <code>seconds</code> argument. |
| * |
| * @param msg a <code>String</code> 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); |
| servlet = null; |
| if (seconds <= 0) |
| this.seconds = -1; |
| else |
| this.seconds = seconds; |
| |
| permanent = false; |
| } |
| |
| /** |
| * Returns a <code>boolean</code> 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 <code>true</code> if the servlet is |
| * permanently unavailable; <code>false</code> |
| * if the servlet is available or temporarily |
| * unavailable |
| */ |
| public boolean isPermanent() { |
| return permanent; |
| } |
| |
| /** |
| * @deprecated As of Java Servlet API 2.2, with no replacement. |
| * <p/> |
| * Returns the servlet that is reporting its unavailability. |
| * @return the <code>Servlet</code> object that is |
| * throwing the <code>UnavailableException</code> |
| */ |
| public Servlet getServlet() { |
| return servlet; |
| } |
| |
| /** |
| * Returns the number of seconds the servlet expects to |
| * be temporarily unavailable. |
| * <p/> |
| * <p>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; |
| } |
| |
| } |