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package javax.servlet;

import java.util.EventListener;

Interface for receiving notification events about ServletContext
lifecycle changes.
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 contextInitialized method in the order in which they have been declared, and at their contextDestroyed method in reverse order. 
See Also:
ServletContextEvent
Since:
Servlet 2.3/** 
 * Interface for receiving notification events about ServletContext
 * lifecycle changes.
 *
 * <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 #contextInitialized} method in the order in which they have been
 * declared, and at their {@link #contextDestroyed} method in reverse
 * order.
 *
 * @see ServletContextEvent
 *
 * @since Servlet 2.3
 */
public interface ServletContextListener extends EventListener {

    
Receives notification that the web application initialization
process is starting.
All ServletContextListeners are notified of context
initialization before any filters or servlets in the web
application are initialized.
Params:
sce – the ServletContextEvent containing the ServletContext
that is being initialized
Implementation Requirements:

The default implementation takes no action./**
     * Receives notification that the web application initialization
     * process is starting.
     *
     * <p>All ServletContextListeners are notified of context
     * initialization before any filters or servlets in the web
     * application are initialized.
     *
     * @param sce the ServletContextEvent containing the ServletContext
     * that is being initialized
     *
     * @implSpec
     * The default implementation takes no action.
     */
    default public void contextInitialized(ServletContextEvent sce) {}

    
Receives notification that the ServletContext is about to be
shut down.
All servlets and filters will have been destroyed before any
ServletContextListeners are notified of context
destruction.
Params:
sce – the ServletContextEvent containing the ServletContext
that is being destroyed
Implementation Requirements:

The default implementation takes no action./**
     * Receives notification that the ServletContext is about to be
     * shut down.
     *
     * <p>All servlets and filters will have been destroyed before any
     * ServletContextListeners are notified of context
     * destruction.
     *
     * @param sce the ServletContextEvent containing the ServletContext
     * that is being destroyed
     *
     * @implSpec
     * The default implementation takes no action.
     */
    default public void contextDestroyed(ServletContextEvent sce) {}
}