81 lines
2.6 KiB
Java
81 lines
2.6 KiB
Java
/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* $Header:$
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*/
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package org.apache.beehive.controls.runtime.bean;
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import java.util.TooManyListenersException;
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/**
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* The UnicastEventNotifier class provides basic callback listener management and event delivery
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* services for unicast EventSets on ControlBean instances.
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*/
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public class UnicastEventNotifier implements java.io.Serializable
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{
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/**
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* Adds a new callback event listener for this EventNotifier. This method will also
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* perform a check to see if there is already a register listener, and throw a
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* <code>java.util.TooManyListenersException</code> if there is already a registered
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* listener.
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*/
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synchronized public void addListener(Object listener) throws TooManyListenersException
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{
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if (_listener != null)
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throw new TooManyListenersException("Callback listener is already registered");
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_listener = listener;
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}
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/**
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* Remove an existing callback event listener for this EventNotifier
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*/
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synchronized public void removeListener(Object listener)
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{
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if (_listener != listener)
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{
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throw new IllegalStateException("Invalid listener, not currently registered");
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}
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_listener = null;
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}
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/**
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* Returns the listener associated with this EventNotifier
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*/
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public Object getListener()
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{
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return _listener;
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}
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/**
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* Returns the number of registered listeners
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*/
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public int getListenerCount()
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{
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return (_listener != null) ? 1 : 0;
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}
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/**
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* Returns the listener list in array form
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*/
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public void getListeners(Object [] listeners)
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{
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if (_listener != null)
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listeners[0] = _listener;
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}
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private Object _listener;
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}
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