/** 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 javax.servlet;import java.util.EventListener;    /**     * A ServletRequestAttributeListener can be implemented by the     * developer interested in being notified of request attribute     * changes. Notifications will be generated while the request     * is within the scope of the web application in which the listener     * is registered. A request is defined as coming into scope when     * it is about to enter the first servlet or filter in each web     * application, as going out of scope when it exits the last servlet     * or the first filter in the chain.     *     * @since Servlet 2.4     */public interface ServletRequestAttributeListener extends EventListener {    /** Notification that a new attribute was added to the     ** servlet request. Called after the attribute is added.     */    public void attributeAdded(ServletRequestAttributeEvent srae);    /** Notification that an existing attribute has been removed from the     ** servlet request. Called after the attribute is removed.     */    public void attributeRemoved(ServletRequestAttributeEvent srae);    /** Notification that an attribute was replaced on the     ** servlet request. Called after the attribute is replaced.     */    public void attributeReplaced(ServletRequestAttributeEvent srae);}