001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one
003     * or more contributor license agreements.  See the NOTICE file
004     * distributed with this work for additional information
005     * regarding copyright ownership.  The ASF licenses this file
006     * to you under the Apache License, Version 2.0 (the
007     * "License"); you may not use this file except in compliance
008     * with the License.  You may obtain a copy of the License at
009     *
010     *  http://www.apache.org/licenses/LICENSE-2.0
011     *
012     * Unless required by applicable law or agreed to in writing,
013     * software distributed under the License is distributed on an
014     * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015     * KIND, either express or implied.  See the License for the
016     * specific language governing permissions and limitations
017     * under the License.
018     */
019    
020    package javax.servlet;
021    
022    import java.util.EventListener;
023    
024    /**
025     * A ServletRequestAttributeListener can be implemented by the
026     * developer interested in being notified of request attribute
027     * changes. Notifications will be generated while the request
028     * is within the scope of the web application in which the listener
029     * is registered. A request is defined as coming into scope when
030     * it is about to enter the first servlet or filter in each web
031     * application, as going out of scope when it exits the last servlet
032     * or the first filter in the chain.
033     *
034     * @since Servlet 2.4
035     * @version $Rev: 835965 $ $Date: 2009-11-13 14:40:44 -0500 (Fri, 13 Nov 2009) $
036     */
037    
038    public interface ServletRequestAttributeListener extends EventListener {
039        /**
040         * Notification that a new attribute was added to the
041         * * servlet request. Called after the attribute is added.
042         * @param srae event for attribute added
043         */
044        void attributeAdded(ServletRequestAttributeEvent srae);
045    
046        /**
047         * Notification that an existing attribute has been removed from the
048         * * servlet request. Called after the attribute is removed.
049         * @param srae event for attribute removed
050         */
051        void attributeRemoved(ServletRequestAttributeEvent srae);
052    
053        /**
054         * Notification that an attribute was replaced on the
055         * * servlet request. Called after the attribute is replaced.
056         * @param srae event for attribute replaced
057         */
058        void attributeReplaced(ServletRequestAttributeEvent srae);
059    }
060