UnavailableException.java
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上传日期:2022-07-20
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数据库编程
开发平台:
Java
- /*
- * The Apache Software License, Version 1.1
- *
- * Copyright (c) 1999 The Apache Software Foundation. All rights
- * reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in
- * the documentation and/or other materials provided with the
- * distribution.
- *
- * 3. The end-user documentation included with the redistribution, if
- * any, must include the following acknowlegement:
- * "This product includes software developed by the
- * Apache Software Foundation (http://www.apache.org/)."
- * Alternately, this acknowlegement may appear in the software itself,
- * if and wherever such third-party acknowlegements normally appear.
- *
- * 4. The names "The Jakarta Project", "Tomcat", and "Apache Software
- * Foundation" must not be used to endorse or promote products derived
- * from this software without prior written permission. For written
- * permission, please contact apache@apache.org.
- *
- * 5. Products derived from this software may not be called "Apache"
- * nor may "Apache" appear in their names without prior written
- * permission of the Apache Group.
- *
- * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
- * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
- * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
- * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
- * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
- * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
- * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- * ====================================================================
- *
- * This software consists of voluntary contributions made by many
- * individuals on behalf of the Apache Software Foundation. For more
- * information on the Apache Software Foundation, please see
- * <http://www.apache.org/>.
- *
- * ====================================================================
- *
- * 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 throws to indicate
- * that it is permanently or temporarily unavailable.
- *
- * <p>When a servlet is permanently unavailable, something is wrong
- * with the servlet, and it cannot handle
- * requests until some action is taken. For example, the servlet
- * might be configured incorrectly, or its state may be corrupted.
- * A servlet should log both the error and the corrective action
- * that is needed.
- *
- * <p>A servlet 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>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 for a period
- * of time suggested by the servlet, rather than rejecting them until
- * the servlet container restarts.
- *
- *
- * @author Various
- * @version $Version$
- *
- */
- public class UnavailableException
- extends ServletException {
- private Servlet servlet; // what's unavailable
- private boolean permanent; // needs admin action?
- private int seconds; // unavailability estimate
- /**
- *
- * @deprecated As of Java Servlet API 2.2, use {@link
- * #UnavailableException(String)} instead.
- *
- * @param servlet the <code>Servlet</code> instance that is
- * unavailable
- *
- * @param msg a <code>String</code> 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 <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.
- *
- */
- 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);
- 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.
- *
- * <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);
- 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.
- *
- * 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>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;
- }
- }