org.snmp4j.mp.CounterSupport Maven / Gradle / Ivy
/*_############################################################################
_##
_## SNMP4J - CounterSupport.java
_##
_## Copyright (C) 2003-2020 Frank Fock (SNMP4J.org)
_##
_## Licensed under the Apache License, Version 2.0 (the "License");
_## you may not use this file except in compliance with the License.
_## You may obtain a copy of the License at
_##
_## http://www.apache.org/licenses/LICENSE-2.0
_##
_## Unless required by applicable law or agreed to in writing, software
_## distributed under the License is distributed on an "AS IS" BASIS,
_## WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
_## See the License for the specific language governing permissions and
_## limitations under the License.
_##
_##########################################################################*/
package org.snmp4j.mp;
import org.snmp4j.event.*;
import java.util.*;
/**
* The CounterSupport class provides support to fire
* {@link CounterEvent} to registered listeners.
* @author Frank Fock
* @version 1.0
*/
public class CounterSupport {
protected static CounterSupport instance = null;
private transient Vector counterListeners;
protected CounterSupport() {
}
/**
* Gets the counter support singleton.
* @return
* the CounterSupport instance.
*/
public static CounterSupport getInstance() {
if (instance == null) {
instance = new CounterSupport();
}
return instance;
}
/**
* Adds a CounterListener.
* @param listener
* a CounterListener instance that needs to be informed when
* a counter needs to be incremented.
*/
public synchronized void addCounterListener(CounterListener listener) {
if (counterListeners == null) {
counterListeners = new Vector(2);
}
if (!counterListeners.contains(listener)) {
counterListeners.add(listener);
}
}
/**
* Removes a previously added CounterListener.
* @param listener
* a CounterListener instance.
*/
public synchronized void removeCounterListener(CounterListener listener) {
if (counterListeners != null && counterListeners.contains(listener)) {
counterListeners.removeElement(listener);
}
}
/**
* Inform all registered listeners that the supplied counter needs to be
* incremented.
* @param event
* a CounterEvent containing information about the counter to
* be incremented.
*/
public void fireIncrementCounter(CounterEvent event) {
if (counterListeners != null) {
for (CounterListener l: counterListeners) {
l.incrementCounter(event);
}
}
}
}