jakarta.servlet.ServletContainerInitializer Maven / Gradle / Ivy
/*
* Copyright (c) 2017, 2023 Oracle and/or its affiliates and others.
* All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0, which is available at
* http://www.eclipse.org/legal/epl-2.0.
*
* This Source Code may also be made available under the following Secondary
* Licenses when the conditions for such availability set forth in the
* Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
* version 2 with the GNU Classpath Exception, which is available at
* https://www.gnu.org/software/classpath/license.html.
*
* SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
*/
package jakarta.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.
*
*
* Implementations of this interface may be annotated with {@link jakarta.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.
*
*
* If an implementation of this interface does not use HandlesTypes annotation, or none of the application
* classes match the ones specified by the annotation, the container must pass a null Set of classes to
* {@link #onStartup}.
*
*
* When examining the classes of an application to see if they match any of the criteria specified by the
* HandlesTypes annotation of a ServletContainerInitializer, 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.
*
*
* Implementations of this interface must be declared by a JAR file resource located inside the
* META-INF/services 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, ServletContainerInitializer 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 jakarta.servlet.annotation.HandlesTypes
*
* @since Servlet 3.0
*/
public interface ServletContainerInitializer {
/**
* Notifies this ServletContainerInitializer of the startup of the application represented by the given
* ServletContext.
*
*
* If this ServletContainerInitializer is bundled in a JAR file inside the WEB-INF/lib directory of an
* application, its onStartup method will be invoked only once during the startup of the bundling application.
* If this ServletContainerInitializer is bundled inside a JAR file outside of any WEB-INF/lib
* directory, but still discoverable as described above, its onStartup 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 jakarta.servlet.annotation.HandlesTypes HandlesTypes} annotation, or null if there are no
* matches, or this ServletContainerInitializer has not been annotated with HandlesTypes
*
* @param ctx the ServletContext of the web application that is being started and in which the classes
* contained in c were found
*
* @throws ServletException if an error has occurred
*/
void onStartup(Set> c, ServletContext ctx) throws ServletException;
}