| /* |
| * Copyright 2004 The Apache Software Foundation |
| * |
| * Licensed 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 listeners; |
| |
| |
| import javax.servlet.ServletContext; |
| import javax.servlet.ServletContextAttributeEvent; |
| import javax.servlet.ServletContextAttributeListener; |
| import javax.servlet.ServletContextEvent; |
| import javax.servlet.ServletContextListener; |
| |
| |
| /** |
| * Example listener for context-related application events, which were |
| * introduced in the 2.3 version of the Servlet API. This listener |
| * merely documents the occurrence of such events in the application log |
| * associated with our servlet context. |
| * |
| * @author Craig R. McClanahan |
| * @version $Revision$ $Date$ |
| */ |
| |
| public final class ContextListener |
| implements ServletContextAttributeListener, ServletContextListener { |
| |
| |
| // ----------------------------------------------------- Instance Variables |
| |
| |
| /** |
| * The servlet context with which we are associated. |
| */ |
| private ServletContext context = null; |
| |
| |
| // --------------------------------------------------------- Public Methods |
| |
| |
| /** |
| * Record the fact that a servlet context attribute was added. |
| * |
| * @param event The servlet context attribute event |
| */ |
| public void attributeAdded(ServletContextAttributeEvent event) { |
| |
| log("attributeAdded('" + event.getName() + "', '" + |
| event.getValue() + "')"); |
| |
| } |
| |
| |
| /** |
| * Record the fact that a servlet context attribute was removed. |
| * |
| * @param event The servlet context attribute event |
| */ |
| public void attributeRemoved(ServletContextAttributeEvent event) { |
| |
| log("attributeRemoved('" + event.getName() + "', '" + |
| event.getValue() + "')"); |
| |
| } |
| |
| |
| /** |
| * Record the fact that a servlet context attribute was replaced. |
| * |
| * @param event The servlet context attribute event |
| */ |
| public void attributeReplaced(ServletContextAttributeEvent event) { |
| |
| log("attributeReplaced('" + event.getName() + "', '" + |
| event.getValue() + "')"); |
| |
| } |
| |
| |
| /** |
| * Record the fact that this web application has been destroyed. |
| * |
| * @param event The servlet context event |
| */ |
| public void contextDestroyed(ServletContextEvent event) { |
| |
| log("contextDestroyed()"); |
| this.context = null; |
| |
| } |
| |
| |
| /** |
| * Record the fact that this web application has been initialized. |
| * |
| * @param event The servlet context event |
| */ |
| public void contextInitialized(ServletContextEvent event) { |
| |
| this.context = event.getServletContext(); |
| log("contextInitialized()"); |
| |
| } |
| |
| |
| // -------------------------------------------------------- Private Methods |
| |
| |
| /** |
| * Log a message to the servlet context application log. |
| * |
| * @param message Message to be logged |
| */ |
| private void log(String message) { |
| |
| if (context != null) |
| context.log("ContextListener: " + message); |
| else |
| System.out.println("ContextListener: " + message); |
| |
| } |
| |
| |
| /** |
| * Log a message and associated exception to the servlet context |
| * application log. |
| * |
| * @param message Message to be logged |
| * @param throwable Exception to be logged |
| */ |
| private void log(String message, Throwable throwable) { |
| |
| if (context != null) |
| context.log("ContextListener: " + message, throwable); |
| else { |
| System.out.println("ContextListener: " + message); |
| throwable.printStackTrace(System.out); |
| } |
| |
| } |
| |
| |
| } |