1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18
19 package listeners;
20
21
22 import javax.servlet.ServletContext;
23 import javax.servlet.ServletContextEvent;
24 import javax.servlet.ServletContextListener;
25 import javax.servlet.http.HttpSessionAttributeListener;
26 import javax.servlet.http.HttpSessionBindingEvent;
27 import javax.servlet.http.HttpSessionEvent;
28 import javax.servlet.http.HttpSessionListener;
29
30
31 /**
32 * Example listener for context-related application events, which were
33 * introduced in the 2.3 version of the Servlet API. This listener
34 * merely documents the occurrence of such events in the application log
35 * associated with our servlet context.
36 *
37 * @author Craig R. McClanahan
38 * @version $Revision: 664175 $ $Date: 2008-06-06 18:43:44 -0400 (Fri, 06 Jun 2008) $
39 */
40
41 public final class SessionListener
42 implements ServletContextListener,
43 HttpSessionAttributeListener, HttpSessionListener {
44
45 // ----------------------------------------------------- Instance Variables
46
47
48 /**
49 * The servlet context with which we are associated.
50 */
51 private ServletContext context = null;
52
53 // --------------------------------------------------------- Public Methods
54
55
56 /**
57 * Record the fact that a servlet context attribute was added.
58 *
59 * @param event The session attribute event
60 */
61 public void attributeAdded(HttpSessionBindingEvent event) {
62
63 log("attributeAdded('" + event.getSession().getId() + "', '" +
64 event.getName() + "', '" + event.getValue() + "')");
65
66 }
67
68
69 /**
70 * Record the fact that a servlet context attribute was removed.
71 *
72 * @param event The session attribute event
73 */
74 public void attributeRemoved(HttpSessionBindingEvent event) {
75
76 log("attributeRemoved('" + event.getSession().getId() + "', '" +
77 event.getName() + "', '" + event.getValue() + "')");
78
79 }
80
81
82 /**
83 * Record the fact that a servlet context attribute was replaced.
84 *
85 * @param event The session attribute event
86 */
87 public void attributeReplaced(HttpSessionBindingEvent event) {
88
89 log("attributeReplaced('" + event.getSession().getId() + "', '" +
90 event.getName() + "', '" + event.getValue() + "')");
91
92 }
93
94
95 /**
96 * Record the fact that this web application has been destroyed.
97 *
98 * @param event The servlet context event
99 */
100 public void contextDestroyed(ServletContextEvent event) {
101
102 log("contextDestroyed()");
103 this.context = null;
104
105 }
106
107
108 /**
109 * Record the fact that this web application has been initialized.
110 *
111 * @param event The servlet context event
112 */
113 public void contextInitialized(ServletContextEvent event) {
114
115 this.context = event.getServletContext();
116 log("contextInitialized()");
117
118 }
119
120
121 /**
122 * Record the fact that a session has been created.
123 *
124 * @param event The session event
125 */
126 public void sessionCreated(HttpSessionEvent event) {
127
128 log("sessionCreated('" + event.getSession().getId() + "')");
129
130 }
131
132
133 /**
134 * Record the fact that a session has been destroyed.
135 *
136 * @param event The session event
137 */
138 public void sessionDestroyed(HttpSessionEvent event) {
139
140 log("sessionDestroyed('" + event.getSession().getId() + "')");
141
142 }
143
144 // -------------------------------------------------------- Private Methods
145
146
147 /**
148 * Log a message to the servlet context application log.
149 *
150 * @param message Message to be logged
151 */
152 private void log(String message) {
153
154 if (context != null)
155 context.log("SessionListener: " + message);
156 else
157 System.out.println("SessionListener: " + message);
158
159 }
160
161
162 /**
163 * Log a message and associated exception to the servlet context
164 * application log.
165 *
166 * @param message Message to be logged
167 * @param throwable Exception to be logged
168 */
169 private void log(String message, Throwable throwable) {
170
171 if (context != null)
172 context.log("SessionListener: " + message, throwable);
173 else {
174 System.out.println("SessionListener: " + message);
175 throwable.printStackTrace(System.out);
176 }
177
178 }
179
180
181 }