- 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, Filter)
, 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
-
Constructor Summary
ConstructorDescriptionStoreListeners
(StoreListeners parent, Resource source) Creates a new instance with the given parent and initially no listener. -
Method Summary
Modifier and TypeMethodDescription<E extends StoreEvent>
voidaddListener
(Class<E> eventType, StoreListener<? super E> listener) Registers a listener to notify when the specified kind of event occurs.void
close()
Sends aCloseEvent
to all listeners registered for that kind of event, then discards listeners in this instance (but not in parents).<E 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 parent set of listeners that are notified in addition to this set of listeners.Returns the source of events.Returns a short name or label for the source.<E extends StoreEvent>
booleanhasListener
(Class<E> eventType, StoreListener<? super E> listener) Returnstrue
if the given listener is registered for the given type or a super-type.boolean
hasListeners
(Class<? extends StoreEvent> eventType) Returnstrue
if at least one listener is registered for the given type or a super-type.<E extends StoreEvent>
voidremoveListener
(Class<E> eventType, StoreListener<? super E> listener) Unregisters a listener previously added for the given type of events.void
setUsableEventTypes
(Class<?>... permitted) Notifies thisStoreListeners
that only events of the specified types will be fired.Returns a string representation for debugging purposes.void
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.void
warning
(LogRecord description, Filter onUnhandled) 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.Permitted even types
If the parent restricts the usable event types to a subset ofStoreEvent
subtypes, then thisStoreListeners
inherits those restrictions. The list of usable types can be rectricted more but cannot be relaxed.- Parameters:
parent
- the manager to notify in addition to this manager, ornull
if none.source
- the source of events. Cannot be null.
-
-
Method Details
-
getParent
Returns the parent set of listeners that are notified in addition to this set of listeners. This is the value of theparent
argument given to the constructor.- Returns:
- parent set of listeners that are notified in addition to this set of listeners.
- Since:
- 1.3
-
getSource
Returns the source of events. This value is specified at construction time.- Returns:
- the source of events (never
null
).
-
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 a name from the data store, or returns an arbitrary name if no better name is found.
- 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 cannot 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 are no registered listeners for theWarningEvent
type, then theLogRecord
will be sent to aLogger
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).- Parameters:
level
- the warning level.message
- the message to log, ornull
if none.exception
- the exception to log, ornull
if none.
-
warning
Reports a warning described by the given log record. Invoking this method is equivalent to invokingwarning(LogRecord, Filter)
with a null filter.- Parameters:
description
- warning details provided as a log record.
-
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.onUnhandled.isLoggable(description)
if above step found no listener and theonUnhandled
filter is non-null.Logger.getLogger(record.loggerName).log(record)
if the filter in above step returnedtrue
(or if the filter is null). In that case,loggerName
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.onUnhandled
- filter invoked if the record has not been handled by aStoreListener
, ornull
if none. This filter determines whether the record should be sent to the logger returned bygetLogger()
.- Since:
- 1.2
-
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.If one or many
StoreListener.eventOccured(StoreEvent)
implemetations throw aRuntimeException
, those exceptions will be collected and reported in a single log record. Runtime exceptions in listeners do not cause this method to fail.- Type Parameters:
E
- compile-time value of theeventType
argument.- Parameters:
eventType
- the type of the event to be fired.event
- the event to fire.- Returns:
true
if the event has been sent to at least one listener.- Throws:
IllegalArgumentException
- if the given event type is not one of the types of events that thisStoreListeners
can fire.- Since:
- 1.3
- See Also:
-
addListener
public <E extends StoreEvent> void addListener(Class<E> eventType, StoreListener<? super E> 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:
E
- compile-time value of theeventType
argument.- Parameters:
eventType
- type ofStoreEvent
to listen (cannot benull
).listener
- listener to notify about events.- See Also:
-
removeListener
public <E extends StoreEvent> void removeListener(Class<E> eventType, StoreListener<? super E> 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 are no remaining listeners for warning events, then thisStoreListeners
will send future warnings to the loggers.- Type Parameters:
E
- compile-time value of theeventType
argument.- Parameters:
eventType
- type ofStoreEvent
which were listened (cannot benull
).listener
- listener to stop notifying about events.- See Also:
-
hasListener
public <E extends StoreEvent> boolean hasListener(Class<E> eventType, StoreListener<? super E> listener) Returnstrue
if the given listener is registered for the given type or a super-type. This method may unconditionally returnfalse
if the given type of event is never fired by thisStoreListeners
, because calls toaddListener(eventType, …)
are free to ignore the listeners for those types.- Type Parameters:
E
- compile-time value of theeventType
argument.- Parameters:
eventType
- type ofStoreEvent
to check (cannot benull
).listener
- listener to check for registration.- Returns:
true
if this object contains the specified listener for given event type,false
otherwise.- Since:
- 1.3
-
hasListeners
Returnstrue
if at least one listener is registered for the given type or a super-type. This method may unconditionally returnfalse
if the given type of event is never fired by thisStoreListeners
, because calls toaddListener(eventType, …)
are free to ignore the listeners for those types.- 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.
-
setUsableEventTypes
Notifies thisStoreListeners
that only events of the specified types will be fired. With this knowledge,StoreListeners
will not retain any reference to listeners that are not listening to events of those types or to events of a parent type. This restriction allows the garbage collector to dispose unnecessary listeners.The argument shall enumerate all permitted types, including sub-types (they are not automatically accepted). All types given in argument must be types that were accepted before the invocation of this method. In other words, this method can be invoked for reducing the set of permitted types but not for expanding it.
Example
an application may unconditionally register listeners for being notified about additions of new data. If aDataStore
implementation is read-only, then such listeners would never receive any notification. As a slight optimization, theDataStore
constructor can invoke this method for example as below:listeners.setUsableEventTypes(WarningEvent.class);
addListener(DataAddedEvent.class, foo)
will be ignored, thus avoiding this instance to retain a never-used reference to thefoo
listener.- Parameters:
permitted
- type of events that are permitted. Permitted sub-types shall be explicitly enumerated as well.- Throws:
IllegalArgumentException
- if one of the given types was not permitted before invocation of this method.- Since:
- 1.2
- See Also:
-
useReadOnlyEvents
public void useReadOnlyEvents()Notifies thisStoreListeners
that it will fire onlyWarningEvent
s andCloseEvent
. This method is a shortcut forsetUsableEventTypes(WarningEvent.class, CloseEvent.class)}
, provided because frequently used by read-only data store implementations.Declaring a root resource (typically a
DataStore
) as read-only implies that all children (e.g. components of an aggregate) are also read-only.- Since:
- 1.3
- See Also:
-
close
public void close()Sends aCloseEvent
to all listeners registered for that kind of event, then discards listeners in this instance (but not in parents). Because listeners are discarded, invoking this method many times on the same instance has no effect after the first invocation.If one or many
StoreListener.eventOccured(StoreEvent)
implementations throw aRuntimeException
, those exceptions will be collected and reported in a single log record. Runtime exceptions in listeners do not cause this method to fail.- Since:
- 1.3
- See Also:
-
toString
Returns a string representation for debugging purposes.
-