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/*
* Copyright (c) 1997, 2020 Oracle and/or its affiliates. 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.faces.context;
import jakarta.faces.FacesException;
import jakarta.faces.event.AbortProcessingException;
import jakarta.faces.event.ExceptionQueuedEvent;
import jakarta.faces.event.SystemEvent;
import jakarta.faces.event.SystemEventListener;
/**
*
* ExceptionHandler is the central point for handling unexpected
* Exceptions that are thrown during the Faces lifecycle. The ExceptionHandler must not be
* notified of any Exceptions that occur during application startup or shutdown.
*
*
*
*
*
* See the Jakarta Faces Specification Document for the requirements for the default implementation. Exceptions may
* be passed to the ExceptionHandler in one of two ways:
*
*
*
*
* -
*
* by ensuring that Exceptions are not caught, or are caught and re-thrown.
*
*
*
* This approach allows the ExceptionHandler facility specified in
* section 6.2 "ExceptionHandler" of the Jakarta Faces Specification Document to
* operate on the Exception.
*
*
*
*
* -
*
* By using the system event facility to publish an {@link ExceptionQueuedEvent} that wraps the Exception.
*
*
*
* This approach requires manually publishing the {@link ExceptionQueuedEvent}, but allows more information about the
* Exceptionto be stored in the event. The following code is an example of how to do this.
*
*
*
*
*
* //...
* } catch (Exception e) {
* FacesContext ctx = FacesContext.getCurrentInstance();
* ExceptionQueuedEventContext eventContext = new ExceptionQueuedEventContext(ctx, e);
* eventContext.getAttributes().put("key", "value");
* ctx.getApplication().publishEvent(ExceptionQueuedEvent.class, eventContext);
* }
*
*
*
*
*
* Because the Exception must not be re-thrown when using this approach, lifecycle processing may continue
* as normal, allowing more Exceptions to be published if necessary.
*
*
*
*
*
*
* With either approach, any ExceptionQueuedEvent instances that are published in this way are accessible
* to the {@link #handle} method, which is called at the end of each lifecycle phase, as specified in
* section 6.2 "ExceptionHandler" of the Jakarta Faces Specification Document.
*
*
*
* Note that if {@link #handle} happens to be invoked during {@link jakarta.faces.event.PhaseId#RENDER_RESPONSE}, the
* recovery options are more limited than when it is invoked during other phases. Specifically, it is not valid to call
* {@link jakarta.faces.application.NavigationHandler#handleNavigation} during {@code RENDER_RESPONSE}.
*
*
*
* Instances of this class are request scoped and are created by virtue of {@link FacesContextFactory#getFacesContext}
* calling {@link ExceptionHandlerFactory#getExceptionHandler}.
*
*
*
*
* @since 2.0
*/
public abstract class ExceptionHandler implements SystemEventListener {
/**
*
* Take action to handle the Exception instances residing inside the {@link ExceptionQueuedEvent} instances
* that have been queued by calls to Application().publishEvent(ExceptionQueuedEvent.class,
* eventContext). The requirements of the default implementation are detailed in
* section 6.2.1 "Default ExceptionHandler implementation" of the Jakarta Faces Specification Document.
*
*
* @throws FacesException if and only if a problem occurs while performing the algorithm to handle the
* Exception, not as a means of conveying a handled Exception itself.
*
* @since 2.0
*/
public abstract void handle() throws FacesException;
/**
*
* Return the first ExceptionQueuedEvent handled by this handler.
*
*
* @return instance of ExceptionQueuedEvent.
*
*/
public abstract ExceptionQueuedEvent getHandledExceptionQueuedEvent();
/**
*
* Return an Iterable over all ExceptionQueuedEvents that have not yet been handled by the
* {@link #handle} method.
*
*
* @return the unhandled set of ExceptionQueuedEvents.
*
*/
public abstract Iterable getUnhandledExceptionQueuedEvents();
/**
*
* The default implementation must return an Iterable over all ExceptionQueuedEvents that have
* been handled by the {@link #handle} method.
*
*
* @return an Iterable over all ExceptionQueuedEvents.
*
*/
public abstract Iterable getHandledExceptionQueuedEvents();
/**
* {@inheritDoc}
*/
@Override
public abstract void processEvent(SystemEvent exceptionQueuedEvent) throws AbortProcessingException;
/**
* {@inheritDoc}
*/
@Override
public abstract boolean isListenerForSource(Object source);
/**
*
* Unwrap the argument t until the unwrapping encounters an Object whose getClass() is not
* equal to FacesException.class or jakarta.el.ELException.class. If there is no root cause,
* null is returned.
*
*
* @param t passed-in wrapped Throwable.
*
* @return unwrapped object.
*
* @throws NullPointerException if argument t is null.
*
* @since 2.0
*/
public abstract Throwable getRootCause(Throwable t);
}