1
2
3 /*
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
5 *
6 * Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.
7 *
8 * Portions Copyright Apache Software Foundation.
9 *
10 * The contents of this file are subject to the terms of either the GNU
11 * General Public License Version 2 only ("GPL") or the Common Development
12 * and Distribution License("CDDL") (collectively, the "License"). You
13 * may not use this file except in compliance with the License. You can obtain
14 * a copy of the License at https://glassfish.dev.java.net/public/CDDL+GPL.html
15 * or glassfish/bootstrap/legal/LICENSE.txt. See the License for the specific
16 * language governing permissions and limitations under the License.
17 *
18 * When distributing the software, include this License Header Notice in each
19 * file and include the License file at glassfish/bootstrap/legal/LICENSE.txt.
20 * Sun designates this particular file as subject to the "Classpath" exception
21 * as provided by Sun in the GPL Version 2 section of the License file that
22 * accompanied this code. If applicable, add the following below the License
23 * Header, with the fields enclosed by brackets [] replaced by your own
24 * identifying information: "Portions Copyrighted [year]
25 * [name of copyright owner]"
26 *
27 * Contributor(s):
28 *
29 * If you wish your version of this file to be governed by only the CDDL or
30 * only the GPL Version 2, indicate your decision by adding "[Contributor]
31 * elects to include this software in this distribution under the [CDDL or GPL
32 * Version 2] license." If you don't indicate a single choice of license, a
33 * recipient has the option to distribute your version of this file under
34 * either the CDDL, the GPL Version 2 or to extend the choice of license to
35 * its licensees as provided above. However, if you add GPL Version 2 code
36 * and therefore, elected the GPL Version 2 license, then the option applies
37 * only if the new code is made subject to such option by the copyright
38 * holder.
39 */
40
41 package javax.servlet;
42
43
44 /**
45 * Defines an exception that a servlet or filter throws to indicate
46 * that it is permanently or temporarily unavailable.
47 *
48 * <p>When a servlet or filter is permanently unavailable, something is wrong
49 * with it, and it cannot handle
50 * requests until some action is taken. For example, a servlet
51 * might be configured incorrectly, or a filter's state may be corrupted.
52 * The component should log both the error and the corrective action
53 * that is needed.
54 *
55 * <p>A servlet or filter is temporarily unavailable if it cannot handle
56 * requests momentarily due to some system-wide problem. For example,
57 * a third-tier server might not be accessible, or there may be
58 * insufficient memory or disk storage to handle requests. A system
59 * administrator may need to take corrective action.
60 *
61 * <p>Servlet containers can safely treat both types of unavailable
62 * exceptions in the same way. However, treating temporary unavailability
63 * effectively makes the servlet container more robust. Specifically,
64 * the servlet container might block requests to the servlet or filter for a period
65 * of time suggested by the exception, rather than rejecting them until
66 * the servlet container restarts.
67 *
68 *
69 * @author Various
70 *
71 */
72
73 public class UnavailableException
74 extends ServletException {
75
76 private Servlet servlet; // what's unavailable
77 private boolean permanent; // needs admin action?
78 private int seconds; // unavailability estimate
79
80 /**
81 *
82 * @deprecated As of Java Servlet API 2.2, use {@link
83 * #UnavailableException(String)} instead.
84 *
85 * @param servlet the <code>Servlet</code> instance that is
86 * unavailable
87 *
88 * @param msg a <code>String</code> specifying the
89 * descriptive message
90 *
91 */
92
93 public UnavailableException(Servlet servlet, String msg) {
94 super(msg);
95 this.servlet = servlet;
96 permanent = true;
97 }
98
99 /**
100 * @deprecated As of Java Servlet API 2.2, use {@link
101 * #UnavailableException(String, int)} instead.
102 *
103 * @param seconds an integer specifying the number of seconds
104 * the servlet expects to be unavailable; if
105 * zero or negative, indicates that the servlet
106 * can't make an estimate
107 *
108 * @param servlet the <code>Servlet</code> that is unavailable
109 *
110 * @param msg a <code>String</code> specifying the descriptive
111 * message, which can be written to a log file or
112 * displayed for the user.
113 *
114 */
115
116 public UnavailableException(int seconds, Servlet servlet, String msg) {
117 super(msg);
118 this.servlet = servlet;
119 if (seconds <= 0)
120 this.seconds = -1;
121 else
122 this.seconds = seconds;
123 permanent = false;
124 }
125
126 /**
127 *
128 * Constructs a new exception with a descriptive
129 * message indicating that the servlet is permanently
130 * unavailable.
131 *
132 * @param msg a <code>String</code> specifying the
133 * descriptive message
134 *
135 */
136
137 public UnavailableException(String msg) {
138 super(msg);
139
140 permanent = true;
141 }
142
143 /**
144 * Constructs a new exception with a descriptive message
145 * indicating that the servlet is temporarily unavailable
146 * and giving an estimate of how long it will be unavailable.
147 *
148 * <p>In some cases, the servlet cannot make an estimate. For
149 * example, the servlet might know that a server it needs is
150 * not running, but not be able to report how long it will take
151 * to be restored to functionality. This can be indicated with
152 * a negative or zero value for the <code>seconds</code> argument.
153 *
154 * @param msg a <code>String</code> specifying the
155 * descriptive message, which can be written
156 * to a log file or displayed for the user.
157 *
158 * @param seconds an integer specifying the number of seconds
159 * the servlet expects to be unavailable; if
160 * zero or negative, indicates that the servlet
161 * can't make an estimate
162 *
163 */
164
165 public UnavailableException(String msg, int seconds) {
166 super(msg);
167
168 if (seconds <= 0)
169 this.seconds = -1;
170 else
171 this.seconds = seconds;
172
173 permanent = false;
174 }
175
176 /**
177 *
178 * Returns a <code>boolean</code> indicating
179 * whether the servlet is permanently unavailable.
180 * If so, something is wrong with the servlet, and the
181 * system administrator must take some corrective action.
182 *
183 * @return <code>true</code> if the servlet is
184 * permanently unavailable; <code>false</code>
185 * if the servlet is available or temporarily
186 * unavailable
187 *
188 */
189
190 public boolean isPermanent() {
191 return permanent;
192 }
193
194 /**
195 * @deprecated As of Java Servlet API 2.2, with no replacement.
196 *
197 * Returns the servlet that is reporting its unavailability.
198 *
199 * @return the <code>Servlet</code> object that is
200 * throwing the <code>UnavailableException</code>
201 *
202 */
203
204 public Servlet getServlet() {
205 return servlet;
206 }
207
208 /**
209 * Returns the number of seconds the servlet expects to
210 * be temporarily unavailable.
211 *
212 * <p>If this method returns a negative number, the servlet
213 * is permanently unavailable or cannot provide an estimate of
214 * how long it will be unavailable. No effort is
215 * made to correct for the time elapsed since the exception was
216 * first reported.
217 *
218 * @return an integer specifying the number of seconds
219 * the servlet will be temporarily unavailable,
220 * or a negative number if the servlet is permanently
221 * unavailable or cannot make an estimate
222 *
223 */
224
225 public int getUnavailableSeconds() {
226 return permanent ? -1 : seconds;
227 }
228 }
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