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 package listeners;
19
20
21 import javax.servlet.ServletContext;
22 import javax.servlet.ServletContextEvent;
23 import javax.servlet.ServletContextListener;
24 import javax.servlet.http.HttpSessionAttributeListener;
25 import javax.servlet.http.HttpSessionBindingEvent;
26 import javax.servlet.http.HttpSessionEvent;
27 import javax.servlet.http.HttpSessionListener;
28
29
30 /**
31 * Example listener for context-related application events, which were
32 * introduced in the 2.3 version of the Servlet API. This listener
33 * merely documents the occurrence of such events in the application log
34 * associated with our servlet context.
35 *
36 * @author Craig R. McClanahan
37 * @version $Revision: 664175 $ $Date: 2008-06-06 18:43:44 -0400 (Fri, 06 Jun 2008) $
38 */
39
40 public final class SessionListener
41 implements ServletContextListener,
42 HttpSessionAttributeListener, HttpSessionListener {
43
44 // ----------------------------------------------------- Instance Variables
45
46
47 /**
48 * The servlet context with which we are associated.
49 */
50 private ServletContext context = null;
51
52 // --------------------------------------------------------- Public Methods
53
54
55 /**
56 * Record the fact that a servlet context attribute was added.
57 *
58 * @param event The session attribute event
59 */
60 public void attributeAdded(HttpSessionBindingEvent event) {
61
62 log("attributeAdded('" + event.getSession().getId() + "', '" +
63 event.getName() + "', '" + event.getValue() + "')");
64
65 }
66
67
68 /**
69 * Record the fact that a servlet context attribute was removed.
70 *
71 * @param event The session attribute event
72 */
73 public void attributeRemoved(HttpSessionBindingEvent event) {
74
75 log("attributeRemoved('" + event.getSession().getId() + "', '" +
76 event.getName() + "', '" + event.getValue() + "')");
77
78 }
79
80
81 /**
82 * Record the fact that a servlet context attribute was replaced.
83 *
84 * @param event The session attribute event
85 */
86 public void attributeReplaced(HttpSessionBindingEvent event) {
87
88 log("attributeReplaced('" + event.getSession().getId() + "', '" +
89 event.getName() + "', '" + event.getValue() + "')");
90
91 }
92
93
94 /**
95 * Record the fact that this web application has been destroyed.
96 *
97 * @param event The servlet context event
98 */
99 public void contextDestroyed(ServletContextEvent event) {
100
101 log("contextDestroyed()");
102 this.context = null;
103
104 }
105
106
107 /**
108 * Record the fact that this web application has been initialized.
109 *
110 * @param event The servlet context event
111 */
112 public void contextInitialized(ServletContextEvent event) {
113
114 this.context = event.getServletContext();
115 log("contextInitialized()");
116
117 }
118
119
120 /**
121 * Record the fact that a session has been created.
122 *
123 * @param event The session event
124 */
125 public void sessionCreated(HttpSessionEvent event) {
126
127 log("sessionCreated('" + event.getSession().getId() + "')");
128
129 }
130
131
132 /**
133 * Record the fact that a session has been destroyed.
134 *
135 * @param event The session event
136 */
137 public void sessionDestroyed(HttpSessionEvent event) {
138
139 log("sessionDestroyed('" + event.getSession().getId() + "')");
140
141 }
142
143 // -------------------------------------------------------- Private Methods
144
145
146 /**
147 * Log a message to the servlet context application log.
148 *
149 * @param message Message to be logged
150 */
151 private void log(String message) {
152
153 if (context != null)
154 context.log("SessionListener: " + message);
155 else
156 System.out.println("SessionListener: " + message);
157
158 }
159
160
161 /**
162 * Log a message and associated exception to the servlet context
163 * application log.
164 *
165 * @param message Message to be logged
166 * @param throwable Exception to be logged
167 */
168 private void log(String message, Throwable throwable) {
169
170 if (context != null)
171 context.log("SessionListener: " + message, throwable);
172 else {
173 System.out.println("SessionListener: " + message);
174 throwable.printStackTrace(System.out);
175 }
176
177 }
178
179
180 }