za.org.coefficient.events
Class EventHandlerRegistry

java.lang.Object
  za.org.coefficient.events.EventHandlerRegistry

public class EventHandlerRegistry
extends java.lang.Object

Class: EventHandlerRegistry Description: EventHandlerRegistry maintains a registry of event handlers. It is used to determine which handlers should receive event notifications. NOTE: This class is implemented using the singleton patttern, which doesn't really work too well in a distributed EJB environment. It is assumed, therefore, that the app is not running in a clustered environment - i.e. this is a singleton for the entire app. Alternative approaches include storing this stuff in the database, and reading from there, or using an external RMI interface via JNDI.

Author:

tfogwill

Field Summary

private static EventHandlerRegistry	instance Singleton instance
private static org.apache.log4j.Logger	log Logger
private java.util.Map	registry Map to hold the registry data

Constructor Summary

private

EventHandlerRegistry() Private constructor to prevent instantiation.

Method Summary

CoefficientEventHandler[]	getHandlers(java.lang.Class eventType) Get the handlers for the spercified event type
CoefficientEventHandler[]	getHandlers(java.lang.String eventType) Get the handlers for the spercified event type
static EventHandlerRegistry	getInstance() Get the singleton instance
void	registerEventHandler(java.lang.Class eventType, CoefficientEventHandler handler) Register a handler with the registry.

Methods inherited from class java.lang.Object

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

Field Detail

log

private static final org.apache.log4j.Logger log

Logger

instance

private static EventHandlerRegistry instance

Singleton instance

registry

private java.util.Map registry

Map to hold the registry data

Constructor Detail

EventHandlerRegistry

private EventHandlerRegistry()

Private constructor to prevent instantiation.

Method Detail

getInstance

public static EventHandlerRegistry getInstance()

Get the singleton instance

Returns:

the EventHandlerRegistry instance

getHandlers

public CoefficientEventHandler[] getHandlers(java.lang.String eventType)

Get the handlers for the spercified event type

Parameters:

eventType - The event type

Returns:

the appropriate handlers

getHandlers

public CoefficientEventHandler[] getHandlers(java.lang.Class eventType)

Get the handlers for the spercified event type

Parameters:

eventType - The event type

Returns:

the appropriate handlers

registerEventHandler

public void registerEventHandler(java.lang.Class eventType,
                                 CoefficientEventHandler handler)

Register a handler with the registry. This will cause it to be notified when an event occurs that matches the specified event type. Matching is done down the class hierarchy, so a handler will be notified if events occur that are subclasses of the type it's registered to handle.

Parameters:

eventType - The base event type(class) to receive notifications about

handler - The handler which will be notified.