https://javaee.github.io/servlet-spec/: Java.net - The Source for Java Technology Collaboration (GlassFish Community) 
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 * Copyright (c) 1997-2018 Oracle and/or its affiliates. All rights reserved.
 * 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;


Interface for receiving notification events about requests coming
into and going out of scope of a web application.

A ServletRequest is defined as coming into scope of a web
application when it is about to enter the first servlet or filter
of the web application, and as going out of scope as it exits
the last servlet or the first filter in the chain.

In order to receive these notification events, the implementation class must be either declared in the deployment descriptor of the web application, annotated with WebListener, or registered via one of the addListener methods defined on ServletContext. 
Implementations of this interface are invoked at their requestInitialized method in the order in which they have been declared, and at their requestDestroyed method in reverse order. 
Since:Servlet 2.4
/**
 * Interface for receiving notification events about requests coming
 * into and going out of scope of a web application.
 *
 * <p>A ServletRequest is defined as coming into scope of a web
 * application when it is about to enter the first servlet or filter
 * of the web application, and as going out of scope as it exits
 * the last servlet or the first filter in the chain.
 *
 * <p>In order to receive these notification events, the implementation
 * class must be either declared in the deployment descriptor of the web
 * application, annotated with {@link javax.servlet.annotation.WebListener}, 
 * or registered via one of the addListener methods defined on
 * {@link ServletContext}.
 *
 * <p>Implementations of this interface are invoked at their
 * {@link #requestInitialized} method in the order in which they have been
 * declared, and at their {@link #requestDestroyed} method in reverse
 * order.
 *
 * @since Servlet 2.4
 */

public interface ServletRequestListener extends EventListener {

    
Receives notification that a ServletRequest is about to go out
of scope of the web application.

Params:
  • sre – the ServletRequestEvent containing the ServletRequest
and the ServletContext representing the web application
Implementation Requirements:
The default implementation takes no action.
/**
     * Receives notification that a ServletRequest is about to go out
     * of scope of the web application.
     *
     * @param sre the ServletRequestEvent containing the ServletRequest
     * and the ServletContext representing the web application
     *
     * @implSpec
     * The default implementation takes no action.
     */
    default public void requestDestroyed(ServletRequestEvent sre) {}

    
Receives notification that a ServletRequest is about to come
into scope of the web application.

Params:
  • sre – the ServletRequestEvent containing the ServletRequest
and the ServletContext representing the web application
Implementation Requirements:
The default implementation takes no action.
/**
     * Receives notification that a ServletRequest is about to come
     * into scope of the web application.
     *
     * @param sre the ServletRequestEvent containing the ServletRequest
     * and the ServletContext representing the web application
     *
     * @implSpec
     * The default implementation takes no action.
     */
    default public void requestInitialized(ServletRequestEvent sre) {}
}