public abstract class ExceptionHandler extends Object implements SystemEventListener
ExceptionHandler is the
central point for handling unexpected
Exception
s that are thrown during the Faces
lifecycle. The ExceptionHandler
must not be notified of
any Exception
s that occur during application startup or
shutdown.
See the specification prose document for the requirements for the
default implementation. Exception
s may be passed to the
ExceptionHandler
in one of two ways:
by ensuring that Exception
s are not caught, or
are caught and re-thrown.
This approach allows the ExceptionHandler
facility specified in section JSF.6.2 to operate on the
Exception
.
By using the system event facility to publish an ExceptionQueuedEvent
that wraps the Exception
.
This approach requires manually publishing the ExceptionQueuedEvent
, but allows more information about the
Exception
to 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 Exception
s to be
published if necessary.
With either approach, any ExceptionQueuedEvent
instances
that are published in this way are accessible to the handle()
method, which is called at the end of each lifecycle phase, as
specified in section JSF.6.2.
Instances of this class are request scoped and are created by
virtue of FacesContextFactory.getFacesContext(java.lang.Object, java.lang.Object, java.lang.Object, javax.faces.lifecycle.Lifecycle)
calling ExceptionHandlerFactory.getExceptionHandler()
.
Constructor and Description |
---|
ExceptionHandler() |
Modifier and Type | Method and Description |
---|---|
abstract ExceptionQueuedEvent |
getHandledExceptionQueuedEvent()
Return the first
|
abstract Iterable<ExceptionQueuedEvent> |
getHandledExceptionQueuedEvents()
The default implementation must
return an |
abstract Throwable |
getRootCause(Throwable t)
Unwrap the argument |
abstract Iterable<ExceptionQueuedEvent> |
getUnhandledExceptionQueuedEvents()
Return an |
abstract void |
handle()
Take action to handle the
|
abstract boolean |
isListenerForSource(Object source)
This method must return
true if and only if this
listener instance is interested in receiving events from the
instance referenced by the source parameter. |
abstract void |
processEvent(SystemEvent exceptionQueuedEvent)
When called, the listener can assume that any guarantees given
in the javadoc for the specific
SystemEvent
subclass are true. |
public abstract void handle() throws FacesException
Take action to handle the
Exception
instances residing inside the ExceptionQueuedEvent
instances that have been queued by calls to
Application().publishEvent(ExceptionQueuedEvent.class,
eventContext)
. The requirements of the default
implementation are detailed in section JSF.6.2.1.
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.public abstract ExceptionQueuedEvent getHandledExceptionQueuedEvent()
Return the first
ExceptionQueuedEvent
handled by this handler.
public abstract Iterable<ExceptionQueuedEvent> getUnhandledExceptionQueuedEvents()
Return an Iterable
over
all ExceptionQueuedEvent
s that have not yet been handled
by the handle()
method.
public abstract Iterable<ExceptionQueuedEvent> getHandledExceptionQueuedEvents()
The default implementation must
return an Iterable
over all
ExceptionQueuedEvent
s that have been handled by the handle()
method.
public abstract void processEvent(SystemEvent exceptionQueuedEvent) throws AbortProcessingException
When called, the listener can assume that any guarantees given
in the javadoc for the specific SystemEvent
subclass are true.
processEvent
in interface SystemEventListener
exceptionQueuedEvent
- the SystemEvent
instance that
is being processed.AbortProcessingException
- if lifecycle processing should
cease for this request.public abstract boolean isListenerForSource(Object source)
This method must return true
if and only if this
listener instance is interested in receiving events from the
instance referenced by the source
parameter.
isListenerForSource
in interface SystemEventListener
source
- the source that is inquiring about the
appropriateness of sending an event to this listener instance.public abstract Throwable getRootCause(Throwable t)
Unwrap the argument t
until the unwrapping encounters an Object whose
getClass()
is not equal to
FacesException.class
or
javax.el.ELException.class
. If there is no root cause, null
is returned.
NullPointerException
- if argument t
is
null
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