Java tutorial
/* * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER. * * Copyright (c) 2017-2017 Oracle and/or its affiliates. All rights reserved. * * The contents of this file are subject to the terms of either the GNU * General Public License Version 2 only ("GPL") or the Common Development * and Distribution License("CDDL") (collectively, the "License"). You * may not use this file except in compliance with the License. You can * obtain a copy of the License at * https://oss.oracle.com/licenses/CDDL+GPL-1.1 * or LICENSE.txt. 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If you don't indicate a single choice of license, a * recipient has the option to distribute your version of this file under * either the CDDL, the GPL Version 2 or to extend the choice of license to * its licensees as provided above. However, if you add GPL Version 2 code * and therefore, elected the GPL Version 2 license, then the option applies * only if the new code is made subject to such option by the copyright * holder. */ package javax.servlet; import java.util.Set; /** * Interface which allows a library/runtime to be notified of a web * application's startup phase and perform any required programmatic * registration of servlets, filters, and listeners in response to it. * * <p>Implementations of this interface may be annotated with * {@link javax.servlet.annotation.HandlesTypes HandlesTypes}, in order to * receive (at their {@link #onStartup} method) the Set of application * classes that implement, extend, or have been annotated with the class * types specified by the annotation. * * <p>If an implementation of this interface does not use <tt>HandlesTypes</tt> * annotation, or none of the application classes match the ones specified * by the annotation, the container must pass a <tt>null</tt> Set of classes * to {@link #onStartup}. * * <p>When examining the classes of an application to see if they match * any of the criteria specified by the <tt>HandlesTypes</tt> annotation * of a <tt>ServletContainerInitializer</tt>, the container may run into * classloading problems if any of the application's optional JAR * files are missing. Because the container is not in a position to decide * whether these types of classloading failures will prevent * the application from working correctly, it must ignore them, * while at the same time providing a configuration option that would * log them. * * <p>Implementations of this interface must be declared by a JAR file * resource located inside the <tt>META-INF/services</tt> directory and * named for the fully qualified class name of this interface, and will be * discovered using the runtime's service provider lookup mechanism * or a container specific mechanism that is semantically equivalent to * it. In either case, <tt>ServletContainerInitializer</tt> services from web * fragment JAR files excluded from an absolute ordering must be ignored, * and the order in which these services are discovered must follow the * application's classloading delegation model. * * @see javax.servlet.annotation.HandlesTypes * * @since Servlet 3.0 */ public interface ServletContainerInitializer { /** * Notifies this <tt>ServletContainerInitializer</tt> of the startup * of the application represented by the given <tt>ServletContext</tt>. * * <p>If this <tt>ServletContainerInitializer</tt> is bundled in a JAR * file inside the <tt>WEB-INF/lib</tt> directory of an application, * its <tt>onStartup</tt> method will be invoked only once during the * startup of the bundling application. If this * <tt>ServletContainerInitializer</tt> is bundled inside a JAR file * outside of any <tt>WEB-INF/lib</tt> directory, but still * discoverable as described above, its <tt>onStartup</tt> method * will be invoked every time an application is started. * * @param c the Set of application classes that extend, implement, or * have been annotated with the class types specified by the * {@link javax.servlet.annotation.HandlesTypes HandlesTypes} annotation, * or <tt>null</tt> if there are no matches, or this * <tt>ServletContainerInitializer</tt> has not been annotated with * <tt>HandlesTypes</tt> * * @param ctx the <tt>ServletContext</tt> of the web application that * is being started and in which the classes contained in <tt>c</tt> * were found * * @throws ServletException if an error has occurred */ public void onStartup(Set<Class<?>> c, ServletContext ctx) throws ServletException; }