bayard 2002/11/11 19:01:05 Added: lang/src/java/org/apache/commons/lang Notifier.java NotifierException.java Log: Notifier is a class which makes handling an event-listener queue a lot easier. It throws the exception when the notify fails. Revision Changes Path 1.1 jakarta-commons/lang/src/java/org/apache/commons/lang/Notifier.java Index: Notifier.java =================================================================== /* ==================================================================== * The Apache Software License, Version 1.1 * * Copyright (c) 2002 The Apache Software Foundation. All rights * reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * * 3. The end-user documentation included with the redistribution, if * any, must include the following acknowlegement: * "This product includes software developed by the * Apache Software Foundation (http://www.apache.org/)." * Alternately, this acknowlegement may appear in the software itself, * if and wherever such third-party acknowlegements normally appear. * * 4. The names "The Jakarta Project", "Commons", and "Apache Software * Foundation" must not be used to endorse or promote products derived * from this software without prior written permission. For written * permission, please contact [EMAIL PROTECTED] * * 5. Products derived from this software may not be called "Apache" * nor may "Apache" appear in their names without prior written * permission of the Apache Software Foundation. * * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * ==================================================================== * * This software consists of voluntary contributions made by many * individuals on behalf of the Apache Software Foundation. For more * information on the Apache Software Foundation, please see * <http://www.apache.org/>. */ package org.apache.commons.lang; import java.util.ArrayList; import java.util.EventObject; import java.util.Iterator; import java.lang.reflect.Method; import java.lang.reflect.InvocationTargetException; /** * A utility which takes much of the pain out of the Event/Listener * system. It handles the collection, and the loop-notification. * Reflection is used for the actual notification call. * * Alternate strategies are usable. For example this class currently * does not enforce a particular interface, which means it cannot * cache that method. Doing this probably makes a lot of sense. */ public class Notifier { private ArrayList listeners = new ArrayList(); private Method listenerMethod; private String methodName; private Class clss; public Notifier() { } public Notifier(Class listener) { this.clss = clss; // now we check methods, if only one of them, then // let's set it Method[] meths = clss.getDeclaredMethods(); if(meths.length == 0) { this.listenerMethod = meths[0]; } } /** * Set the name of the method to call upon the listeners. */ public void setListenerMethod(String name) { this.methodName = name; if(this.clss != null) { try { // then we get the Method object this.listenerMethod = this.clss.getDeclaredMethod(name, new Class[] { EventObject.class} ); } catch(NoSuchMethodException nsme) { // nsme.printStackTrace(); throw new IllegalArgumentException("Method not on Class. "); } } } public void addListener(Object not) { this.listeners.add(not); } public void removeListener(Object not) { this.listeners.remove(not); } public ArrayList getListeners() { ArrayList cloned = new ArrayList(); cloned.addAll(listeners); return cloned; } /** * Convenience method for when a listener has a single method. * Currently this method needs to be called, but it's possible * that by providing the interface class, it can be assumed as * to what the listening method is. */ public void notify(EventObject event) throws NotifierException { if(this.clss == null) { notify(this.methodName, event); } else { notify(this.listenerMethod, event); } } /** * Notify the listeners of a certain event, to a certain method. * This is usable when a Listener has more than one method and * a single Notifier wants to be shared. */ public void notify(Method listenerMethod, EventObject event) throws NotifierException { Iterator itr = getListeners().iterator(); while(itr.hasNext()) { try { Object listener = itr.next(); listenerMethod.invoke( listener, new Object[] { event } ); } catch(SecurityException se) { throw new NotifierException(se); } catch(IllegalAccessException iae) { throw new NotifierException(iae); } catch(IllegalArgumentException iae) { throw new NotifierException(iae); } catch(InvocationTargetException ite) { throw new NotifierException(ite); } } } /** * Notify the listeners of a certain event, to a certain method. * This is usable when a Listener has more than one method and * a single Notifier wants to be shared. */ public void notify(String methodName, EventObject event) throws NotifierException { Iterator itr = getListeners().iterator(); while(itr.hasNext()) { try { Object listener = itr.next(); Class clss = listener.getClass(); Method method = clss.getMethod(methodName, new Class[] { event.getClass() } ); method.invoke( listener, new Object[] { event } ); } catch(SecurityException se) { throw new NotifierException(se); } catch(NoSuchMethodException nsme) { throw new NotifierException(nsme); } catch(IllegalAccessException iae) { throw new NotifierException(iae); } catch(IllegalArgumentException iae) { throw new NotifierException(iae); } catch(InvocationTargetException ite) { throw new NotifierException(ite); } } } } 1.1 jakarta-commons/lang/src/java/org/apache/commons/lang/NotifierException.java Index: NotifierException.java =================================================================== /* ==================================================================== * The Apache Software License, Version 1.1 * * Copyright (c) 2002 The Apache Software Foundation. All rights * reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * * 3. The end-user documentation included with the redistribution, if * any, must include the following acknowlegement: * "This product includes software developed by the * Apache Software Foundation (http://www.apache.org/)." * Alternately, this acknowlegement may appear in the software itself, * if and wherever such third-party acknowlegements normally appear. * * 4. The names "The Jakarta Project", "Commons", and "Apache Software * Foundation" must not be used to endorse or promote products derived * from this software without prior written permission. For written * permission, please contact [EMAIL PROTECTED] * * 5. Products derived from this software may not be called "Apache" * nor may "Apache" appear in their names without prior written * permission of the Apache Software Foundation. * * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * ==================================================================== * * This software consists of voluntary contributions made by many * individuals on behalf of the Apache Software Foundation. For more * information on the Apache Software Foundation, please see * <http://www.apache.org/>. */ package org.apache.commons.lang; import org.apache.commons.lang.exception.NestableException; /** * Exception thrown when something goes wrong in notifying. * * @author <a href="mailto:bayard@;apache.org">Henri Yandell</a> * @version $Id: NotifierException.java,v 1.1 2002/11/12 03:01:05 bayard Exp $ */ public class NotifierException extends NestableException { /** * Constructs a new <code>NotifierException</code> without specified * detail message. */ public NotifierException() { super(); } /** * Constructs a new <code>NotifierException</code> with specified * detail message. * * @param msg the error message. */ public NotifierException(String msg) { super(msg); } /** * Constructs a new <code>NotifierException</code> with specified * nested <code>Throwable</code> root cause. * * @param rootCause the exception or error that caused this exception * to be thrown. */ public NotifierException(Throwable rootCause) { super(rootCause); } /** * Constructs a new <code>NotifierException</code> with specified * detail message and nested <code>Throwable</code> root cause. * * @param msg the error message. * @param rootCause the exception or error that caused this exception * to be thrown. */ public NotifierException(String msg, Throwable rootCause) { super(msg, rootCause); } }
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