Package org.apache.sis.internal.system

Class SystemListener

java.lang.Object

org.apache.sis.internal.system.SystemListener

All Implemented Interfaces:

EventListener

Direct Known Subclasses:

CoordinateOperations, DefaultFactories, OptionalDependency, XmlUtilities

public abstract class SystemListener
extends Object
implements EventListener

Listeners for changes in the Apache SIS system. This listener is used only for rare events, like OSGi module loaded or unloaded. We use this class instead of OSGi listeners in order to keep the SIS library OSGi-independent.

Since:

0.3

Version:

0.6

Field Summary

Fields

Modifier and Type	Field	Description
private static SystemListener[]	listeners	The listeners, or null if none.
private final String	module	The OSGi module symbolic name, as declared in the Bundle-SymbolicName entry of the META-INF/MANIFEST.MF file.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	SystemListener(String module)	Creates a new listener.

Method Summary

Modifier and Type	Method	Description
static void	add(SystemListener listener)	Adds the given listener to the list of listeners to notify when a change occurs.
protected abstract void	classpathChanged()	Invoked when the classpath is likely to have changed.
protected void	databaseChanged()	Invoked when the database content changed.
static void	fireClasspathChanged()	Notifies all registered listeners that the classpath may have changed.
static void	remove(SystemListener listener)	Removes all occurrences (not just the first one) of the given listener.
(package private) static void	removeModule(String name)	Removes all listeners for the module of the given name.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

listeners

private static SystemListener[] listeners

The listeners, or null if none.

module

private final String module

The OSGi module symbolic name, as declared in the Bundle-SymbolicName entry of the META-INF/MANIFEST.MF file. Shall be one of Modules constants. This is used in order to detect which listeners to remove when a module is uninstalled.

Constructor Details

SystemListener

protected SystemListener(String module)

Creates a new listener.

Parameters:

module - the OSGi module symbolic name, as declared in the Bundle-SymbolicName entry of the META-INF/MANIFEST.MF file. Shall be one of Modules constants.

Method Details

add

public static void add(SystemListener listener)

Adds the given listener to the list of listeners to notify when a change occurs. This method doesn't check if the given listener is already present in the array, unless assertions are enabled.

Parameters:

listener - the listener to add. Cannot be null.

remove

public static void remove(SystemListener listener)

Removes all occurrences (not just the first one) of the given listener. Only one occurrence should exist, but this method check all of them as a paranoiac check.`

Parameters:

listener - the listener to remove.

removeModule

static void removeModule(String name)

Removes all listeners for the module of the given name. This method is invoked by OSGiActivator.

Parameters:

name - the name of the module for which to remove listeners, or null if the module to uninstall does not have symbolic name (in which case it is probably not a SIS module).

fireClasspathChanged

public static void fireClasspathChanged()

Notifies all registered listeners that the classpath may have changed.

classpathChanged

protected abstract void classpathChanged()

Invoked when the classpath is likely to have changed. When this method is invoked, any classes using ServiceLoader are advised to clear their cache.

databaseChanged

protected void databaseChanged()

Invoked when the database content changed. When this method is invoked, EPSG and Citations database are advised to clear their cache.

Since:

0.6