Class StoreListeners
- All Implemented Interfaces:
Localized
StoreListener
instances and provides convenience methods for sending events.
This is a helper class for DataStore
and Resource
implementations.
Observers can add listeners for being notified about events,
and producers can invoke one of the warning(…)
and other methods for emitting events.
Warning events
All warnings are given to the listeners asLogRecord
instances (this allows localizable messages
and additional information like stack trace, timestamp, etc.).
This StoreListeners
class provides convenience methods like warning(String, Exception)
,
which build LogRecord
from an exception or from a string. But all those warning(…)
methods
ultimately delegate to warning(LogRecord)
, thus providing a single point that subclasses can override.
When a warning is emitted, the default behavior is:
- Notify all listeners that are registered for a given
WarningEvent
type in thisStoreListeners
and in the parent resource or data store. Each listener will be notified only once, even if the same listener is registered in two or more places. - If previous step found no listener registered for
WarningEvent
, then log the warning in the first logger found in following choices:- The logger specified by
LogRecord.getLoggerName()
if non-null. - Otherwise the logger specified by
DataStoreProvider.getLogger()
if the provider can be found. - Otherwise a logger whose name is the source
DataStore
package name.
- The logger specified by
Thread safety
The sameStoreListeners
instance can be safely used by many threads without synchronization
on the part of the caller. Subclasses should make sure that any overridden methods remain safe to call
from multiple threads.- Since:
- 1.0
Defined in the sis-storage
module
-
Constructor Summary
ConstructorsConstructorDescriptionStoreListeners
(StoreListeners parent, Resource source) Creates a new instance with the given parent and initially no listener. -
Method Summary
Modifier and TypeMethodDescription<T extends StoreEvent>
voidaddListener
(Class<T> eventType, StoreListener<? super T> listener) Registers a listener to notify when the specified kind of event occurs.<T extends StoreEvent>
booleanSends the given event to all listeners registered for the given type or for a super-type.Returns the locale used by this manager, ornull
if unspecified.Returns the logger where to send warnings when no other destination is specified.Returns the source of events.Returns a short name or label for the source.boolean
hasListeners
(Class<? extends StoreEvent> eventType) Returnstrue
if this object or its parent contains at least one listener for the given type of event.<T extends StoreEvent>
voidremoveListener
(Class<T> eventType, StoreListener<? super T> listener) Unregisters a listener previously added for the given type of events.void
Reports a warning described by the given exception.void
Reports a warning described by the given message.void
Reports a warning described by the given message and exception.void
Reports a warning at the given level represented by the given message and exception.void
warning
(LogRecord description) Reports a warning described by the given log record.
-
Constructor Details
-
StoreListeners
Creates a new instance with the given parent and initially no listener. The parent is typically the listeners of theDataStore
that created a resource. When an event is fired, listeners registered in the parent will be notified as well as listeners registered in thisStoreListeners
. Each listener will be notified only once even if it has been registered in two places.- Parameters:
parent
- the manager to notify in addition to this manager, ornull
if none.source
- the source of events. Can not be null.
-
-
Method Details
-
getSource
Returns the source of events. This value is specified at construction time.- Returns:
- the source of events. Never
null
but may bethis
.
-
getSourceName
Returns a short name or label for the source. It may be the name of the file opened by a data store. The returned name can be useful in warning messages for identifying the problematic source.The default implementation fetches that name from the data store, or returns an arbitrary name if it can get it otherwise.
- Returns:
- a short name of label for the source (never
null
). - See Also:
-
getLocale
Returns the locale used by this manager, ornull
if unspecified. That locale is typically inherited from theDataStore
locale and can be used for formatting messages.- Specified by:
getLocale
in interfaceLocalized
- Returns:
- the locale for messages (typically specified by the data store), or
null
if unknown. - See Also:
-
getLogger
Returns the logger where to send warnings when no other destination is specified. This method tries to get the logger fromDataStoreProvider.getLogger()
. If that logger can not be found, then this method infers a logger name from the package name of the source data store. The returned logger is used when:- no listener has been registered for the
WarningEvent
type, and - the
LogRecord
does not specify a logger.
- Returns:
- the logger where to send the warnings when there is no other destination.
- Since:
- 1.1
- See Also:
- no listener has been registered for the
-
warning
Reports a warning described by the given message.This method is a shortcut for
warning(Level.WARNING, message, null)
.- Parameters:
message
- the warning message to report.
-
warning
Reports a warning described by the given exception. The exception stack trace will be omitted at logging time for avoiding to pollute console output (keeping in mind that this method should be invoked only for non-fatal warnings). See below for more explanation.This method is a shortcut for
warning(Level.WARNING, null, exception)
.- Parameters:
exception
- the exception to report.
-
warning
Reports a warning described by the given message and exception. At least one ofmessage
andexception
arguments shall be non-null. If both are non-null, then the exception message will be concatenated after the given message. If the exception is non-null, its stack trace will be omitted at logging time for avoiding to pollute console output (keeping in mind that this method should be invoked only for non-fatal warnings). See below for more explanation.This method is a shortcut for
warning(Level.WARNING, message, exception)
.- Parameters:
message
- the warning message to report, ornull
if none.exception
- the exception to report, ornull
if none.
-
warning
Reports a warning at the given level represented by the given message and exception. At least one ofmessage
andexception
arguments shall be non-null. If both are non-null, then the exception message will be concatenated after the given message.Stack trace omission
If there is no registered listener for theWarningEvent
type, then thewarning(LogRecord)
method will send the record to a logger but without the stack trace. This is done that way because stack traces consume lot of space in the logging files, while being considered implementation details in the context ofStoreListeners
(on the assumption that the logging message provides sufficient information). If the stack trace is desired, then users can either:- invoke
warning(LogRecord)
directly, or - override
warning(LogRecord)
and invokeLogRecord.setThrown(Throwable)
explicitly, or - register a listener which will log the record itself.
- Parameters:
level
- the warning level.message
- the message to log, ornull
if none.exception
- the exception to log, ornull
if none.
- invoke
-
warning
Reports a warning described by the given log record. The default implementation forwards the given record to one of the following destinations, in preference order:StoreListener.eventOccured(new WarningEvent(source, record))
on all listeners registered for this kind of event.- Only if above step found no listener, then
Logging.getLogger(record.loggerName).log(record)
whereloggerName
is one of the following:record.getLoggerName()
if that value is non-null.- Otherwise the value of
DataStoreProvider.getLogger()
if the provider is found. - Otherwise the source
DataStore
package name.
- Parameters:
description
- warning details provided as a log record.
-
fire
Sends the given event to all listeners registered for the given type or for a super-type. This method first notifies the listeners registered in thisStoreListeners
, then notifies listeners registered in parentStoreListeners
s. Each listener will be notified only once even if it has been registered many times.- Type Parameters:
T
- compile-time value of theeventType
argument.- Parameters:
event
- the event to fire.eventType
- the type of events to be fired.- Returns:
true
if the event has been sent to at least one listener.
-
addListener
public <T extends StoreEvent> void addListener(Class<T> eventType, StoreListener<? super T> listener) Registers a listener to notify when the specified kind of event occurs. Registering a listener for a giveneventType
also register the listener for all event sub-types. The same listener can be registered many times, but itsStoreListener.eventOccured(StoreEvent)
method will be invoked only once per event. This filtering applies even if the listener is registered on different resources in the same tree, for example a parent and its children.Warning events
IfeventType
is assignable fromWarningEvent.class
, then registering that listener turns off logging of warning messages for this manager. This side-effect is applied on the assumption that the registered listener will handle warnings in its own way, for example by showing warnings in a widget.- Type Parameters:
T
- compile-time value of theeventType
argument.- Parameters:
eventType
- type ofStoreEvent
to listen (can not benull
).listener
- listener to notify about events.- See Also:
-
removeListener
public <T extends StoreEvent> void removeListener(Class<T> eventType, StoreListener<? super T> listener) Unregisters a listener previously added for the given type of events. TheeventType
must be the exact same class than the one given to theaddListener(…)
method; this method does not remove listeners registered for subclasses and does not remove listeners registered in parent manager.If the same listener has been registered many times for the same even type, then this method removes only the most recent registration. In other words if
addListener(type, ls)
has been invoked twice, thenremoveListener(type, ls)
needs to be invoked twice in order to remove all instances of that listener. If the given listener is not found, then this method does nothing (no exception is thrown).Warning events
IfeventType
isWarningEvent.class
and if, after this method invocation, there is no remaining listener for warning events, then thisStoreListeners
will send future warnings to the loggers.- Type Parameters:
T
- compile-time value of theeventType
argument.- Parameters:
eventType
- type ofStoreEvent
which were listened (can not benull
).listener
- listener to stop notifying about events.- See Also:
-
hasListeners
Returnstrue
if this object or its parent contains at least one listener for the given type of event.- Parameters:
eventType
- the type of event for which to check listener presence.- Returns:
true
if this object contains at least one listener for given event type,false
otherwise.
-