Notifier is a class which makes handling an event-listener queue a lot easier.
It throws the exception when the notify fails. git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/lang/trunk@137121 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Henri Yandell
parent
864c478a4d
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dfac194424
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/* ====================================================================
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* The Apache Software License, Version 1.1
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*
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* Copyright (c) 2002 The Apache Software Foundation. All rights
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* reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* 3. The end-user documentation included with the redistribution, if
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* any, must include the following acknowlegement:
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* "This product includes software developed by the
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* Apache Software Foundation (http://www.apache.org/)."
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* Alternately, this acknowlegement may appear in the software itself,
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* if and wherever such third-party acknowlegements normally appear.
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*
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* 4. The names "The Jakarta Project", "Commons", and "Apache Software
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* Foundation" must not be used to endorse or promote products derived
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* from this software without prior written permission. For written
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* permission, please contact apache@apache.org.
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*
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* 5. Products derived from this software may not be called "Apache"
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* nor may "Apache" appear in their names without prior written
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* permission of the Apache Software Foundation.
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*
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
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* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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* ====================================================================
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*
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* This software consists of voluntary contributions made by many
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* individuals on behalf of the Apache Software Foundation. For more
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* information on the Apache Software Foundation, please see
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* <http://www.apache.org/>.
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*/
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package org.apache.commons.lang;
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import java.util.ArrayList;
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import java.util.EventObject;
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import java.util.Iterator;
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import java.lang.reflect.Method;
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import java.lang.reflect.InvocationTargetException;
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/**
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* A utility which takes much of the pain out of the Event/Listener
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* system. It handles the collection, and the loop-notification.
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* Reflection is used for the actual notification call.
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*
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* Alternate strategies are usable. For example this class currently
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* does not enforce a particular interface, which means it cannot
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* cache that method. Doing this probably makes a lot of sense.
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*/
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public class Notifier {
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private ArrayList listeners = new ArrayList();
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private Method listenerMethod;
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private String methodName;
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private Class clss;
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public Notifier() {
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}
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public Notifier(Class listener) {
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this.clss = clss;
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// now we check methods, if only one of them, then
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// let's set it
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Method[] meths = clss.getDeclaredMethods();
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if(meths.length == 0) {
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this.listenerMethod = meths[0];
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}
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}
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/**
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* Set the name of the method to call upon the listeners.
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*/
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public void setListenerMethod(String name) {
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this.methodName = name;
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if(this.clss != null) {
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try {
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// then we get the Method object
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this.listenerMethod = this.clss.getDeclaredMethod(name, new Class[] { EventObject.class} );
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} catch(NoSuchMethodException nsme) {
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// nsme.printStackTrace();
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throw new IllegalArgumentException("Method not on Class. ");
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}
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}
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}
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public void addListener(Object not) {
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this.listeners.add(not);
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}
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public void removeListener(Object not) {
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this.listeners.remove(not);
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}
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public ArrayList getListeners() {
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ArrayList cloned = new ArrayList();
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cloned.addAll(listeners);
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return cloned;
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}
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/**
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* Convenience method for when a listener has a single method.
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* Currently this method needs to be called, but it's possible
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* that by providing the interface class, it can be assumed as
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* to what the listening method is.
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*/
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public void notify(EventObject event) throws NotifierException {
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if(this.clss == null) {
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notify(this.methodName, event);
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} else {
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notify(this.listenerMethod, event);
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}
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}
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/**
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* Notify the listeners of a certain event, to a certain method.
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* This is usable when a Listener has more than one method and
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* a single Notifier wants to be shared.
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*/
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public void notify(Method listenerMethod, EventObject event) throws NotifierException {
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Iterator itr = getListeners().iterator();
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while(itr.hasNext()) {
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try {
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Object listener = itr.next();
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listenerMethod.invoke( listener, new Object[] { event } );
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} catch(SecurityException se) {
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throw new NotifierException(se);
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} catch(IllegalAccessException iae) {
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throw new NotifierException(iae);
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} catch(IllegalArgumentException iae) {
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throw new NotifierException(iae);
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} catch(InvocationTargetException ite) {
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throw new NotifierException(ite);
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}
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}
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}
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/**
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* Notify the listeners of a certain event, to a certain method.
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* This is usable when a Listener has more than one method and
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* a single Notifier wants to be shared.
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*/
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public void notify(String methodName, EventObject event) throws NotifierException {
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Iterator itr = getListeners().iterator();
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while(itr.hasNext()) {
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try {
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Object listener = itr.next();
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Class clss = listener.getClass();
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Method method = clss.getMethod(methodName, new Class[] { event.getClass() } );
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method.invoke( listener, new Object[] { event } );
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} catch(SecurityException se) {
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throw new NotifierException(se);
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} catch(NoSuchMethodException nsme) {
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throw new NotifierException(nsme);
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} catch(IllegalAccessException iae) {
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throw new NotifierException(iae);
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} catch(IllegalArgumentException iae) {
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throw new NotifierException(iae);
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} catch(InvocationTargetException ite) {
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throw new NotifierException(ite);
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}
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}
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}
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}
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@ -0,0 +1,107 @@
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/* ====================================================================
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* The Apache Software License, Version 1.1
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*
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* Copyright (c) 2002 The Apache Software Foundation. All rights
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* reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
|
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
|
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* 3. The end-user documentation included with the redistribution, if
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* any, must include the following acknowlegement:
|
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* "This product includes software developed by the
|
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* Apache Software Foundation (http://www.apache.org/)."
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* Alternately, this acknowlegement may appear in the software itself,
|
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* if and wherever such third-party acknowlegements normally appear.
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*
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* 4. The names "The Jakarta Project", "Commons", and "Apache Software
|
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* Foundation" must not be used to endorse or promote products derived
|
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* from this software without prior written permission. For written
|
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* permission, please contact apache@apache.org.
|
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*
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* 5. Products derived from this software may not be called "Apache"
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* nor may "Apache" appear in their names without prior written
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* permission of the Apache Software Foundation.
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*
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
|
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
|
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
|
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* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
|
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* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
|
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
|
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
|
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* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
|
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
|
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
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* SUCH DAMAGE.
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* ====================================================================
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*
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* This software consists of voluntary contributions made by many
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* individuals on behalf of the Apache Software Foundation. For more
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* information on the Apache Software Foundation, please see
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* <http://www.apache.org/>.
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*/
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package org.apache.commons.lang;
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import org.apache.commons.lang.exception.NestableException;
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/**
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* Exception thrown when something goes wrong in notifying.
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*
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* @author <a href="mailto:bayard@apache.org">Henri Yandell</a>
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* @version $Id: NotifierException.java,v 1.1 2002/11/12 03:01:05 bayard Exp $
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*/
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public class NotifierException extends NestableException {
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/**
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* Constructs a new <code>NotifierException</code> without specified
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* detail message.
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*/
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public NotifierException() {
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super();
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}
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/**
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* Constructs a new <code>NotifierException</code> with specified
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* detail message.
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*
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* @param msg the error message.
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*/
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public NotifierException(String msg) {
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super(msg);
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}
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/**
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* Constructs a new <code>NotifierException</code> with specified
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* nested <code>Throwable</code> root cause.
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*
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* @param rootCause the exception or error that caused this exception
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* to be thrown.
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*/
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public NotifierException(Throwable rootCause) {
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super(rootCause);
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}
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/**
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* Constructs a new <code>NotifierException</code> with specified
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* detail message and nested <code>Throwable</code> root cause.
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*
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* @param msg the error message.
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* @param rootCause the exception or error that caused this exception
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* to be thrown.
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*/
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public NotifierException(String msg, Throwable rootCause) {
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super(msg, rootCause);
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}
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}
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