| /* |
| * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| package javax.swing.event; |
| |
| import java.io.*; |
| import java.util.*; |
| import java.lang.reflect.Array; |
| import sun.reflect.misc.ReflectUtil; |
| |
| /** |
| * A class that holds a list of EventListeners. A single instance |
| * can be used to hold all listeners (of all types) for the instance |
| * using the list. It is the responsiblity of the class using the |
| * EventListenerList to provide type-safe API (preferably conforming |
| * to the JavaBeans spec) and methods which dispatch event notification |
| * methods to appropriate Event Listeners on the list. |
| * |
| * The main benefits that this class provides are that it is relatively |
| * cheap in the case of no listeners, and it provides serialization for |
| * event-listener lists in a single place, as well as a degree of MT safety |
| * (when used correctly). |
| * |
| * Usage example: |
| * Say one is defining a class that sends out FooEvents, and one wants |
| * to allow users of the class to register FooListeners and receive |
| * notification when FooEvents occur. The following should be added |
| * to the class definition: |
| * <pre> |
| * EventListenerList listenerList = new EventListenerList(); |
| * FooEvent fooEvent = null; |
| * |
| * public void addFooListener(FooListener l) { |
| * listenerList.add(FooListener.class, l); |
| * } |
| * |
| * public void removeFooListener(FooListener l) { |
| * listenerList.remove(FooListener.class, l); |
| * } |
| * |
| * |
| * // Notify all listeners that have registered interest for |
| * // notification on this event type. The event instance |
| * // is lazily created using the parameters passed into |
| * // the fire method. |
| * |
| * protected void fireFooXXX() { |
| * // Guaranteed to return a non-null array |
| * Object[] listeners = listenerList.getListenerList(); |
| * // Process the listeners last to first, notifying |
| * // those that are interested in this event |
| * for (int i = listeners.length-2; i>=0; i-=2) { |
| * if (listeners[i]==FooListener.class) { |
| * // Lazily create the event: |
| * if (fooEvent == null) |
| * fooEvent = new FooEvent(this); |
| * ((FooListener)listeners[i+1]).fooXXX(fooEvent); |
| * } |
| * } |
| * } |
| * </pre> |
| * foo should be changed to the appropriate name, and fireFooXxx to the |
| * appropriate method name. One fire method should exist for each |
| * notification method in the FooListener interface. |
| * <p> |
| * <strong>Warning:</strong> |
| * Serialized objects of this class will not be compatible with |
| * future Swing releases. The current serialization support is |
| * appropriate for short term storage or RMI between applications running |
| * the same version of Swing. As of 1.4, support for long term storage |
| * of all JavaBeans™ |
| * has been added to the <code>java.beans</code> package. |
| * Please see {@link java.beans.XMLEncoder}. |
| * |
| * @author Georges Saab |
| * @author Hans Muller |
| * @author James Gosling |
| */ |
| @SuppressWarnings("serial") |
| public class EventListenerList implements Serializable { |
| /* A null array to be shared by all empty listener lists*/ |
| private final static Object[] NULL_ARRAY = new Object[0]; |
| /* The list of ListenerType - Listener pairs */ |
| protected transient Object[] listenerList = NULL_ARRAY; |
| |
| /** |
| * Passes back the event listener list as an array |
| * of ListenerType-listener pairs. Note that for |
| * performance reasons, this implementation passes back |
| * the actual data structure in which the listener data |
| * is stored internally! |
| * This method is guaranteed to pass back a non-null |
| * array, so that no null-checking is required in |
| * fire methods. A zero-length array of Object should |
| * be returned if there are currently no listeners. |
| * |
| * WARNING!!! Absolutely NO modification of |
| * the data contained in this array should be made -- if |
| * any such manipulation is necessary, it should be done |
| * on a copy of the array returned rather than the array |
| * itself. |
| */ |
| public Object[] getListenerList() { |
| return listenerList; |
| } |
| |
| /** |
| * Return an array of all the listeners of the given type. |
| * @return all of the listeners of the specified type. |
| * @exception ClassCastException if the supplied class |
| * is not assignable to EventListener |
| * |
| * @since 1.3 |
| */ |
| public <T extends EventListener> T[] getListeners(Class<T> t) { |
| Object[] lList = listenerList; |
| int n = getListenerCount(lList, t); |
| T[] result = (T[])Array.newInstance(t, n); |
| int j = 0; |
| for (int i = lList.length-2; i>=0; i-=2) { |
| if (lList[i] == t) { |
| result[j++] = (T)lList[i+1]; |
| } |
| } |
| return result; |
| } |
| |
| /** |
| * Returns the total number of listeners for this listener list. |
| */ |
| public int getListenerCount() { |
| return listenerList.length/2; |
| } |
| |
| /** |
| * Returns the total number of listeners of the supplied type |
| * for this listener list. |
| */ |
| public int getListenerCount(Class<?> t) { |
| Object[] lList = listenerList; |
| return getListenerCount(lList, t); |
| } |
| |
| private int getListenerCount(Object[] list, Class t) { |
| int count = 0; |
| for (int i = 0; i < list.length; i+=2) { |
| if (t == (Class)list[i]) |
| count++; |
| } |
| return count; |
| } |
| |
| /** |
| * Adds the listener as a listener of the specified type. |
| * @param t the type of the listener to be added |
| * @param l the listener to be added |
| */ |
| public synchronized <T extends EventListener> void add(Class<T> t, T l) { |
| if (l==null) { |
| // In an ideal world, we would do an assertion here |
| // to help developers know they are probably doing |
| // something wrong |
| return; |
| } |
| if (!t.isInstance(l)) { |
| throw new IllegalArgumentException("Listener " + l + |
| " is not of type " + t); |
| } |
| if (listenerList == NULL_ARRAY) { |
| // if this is the first listener added, |
| // initialize the lists |
| listenerList = new Object[] { t, l }; |
| } else { |
| // Otherwise copy the array and add the new listener |
| int i = listenerList.length; |
| Object[] tmp = new Object[i+2]; |
| System.arraycopy(listenerList, 0, tmp, 0, i); |
| |
| tmp[i] = t; |
| tmp[i+1] = l; |
| |
| listenerList = tmp; |
| } |
| } |
| |
| /** |
| * Removes the listener as a listener of the specified type. |
| * @param t the type of the listener to be removed |
| * @param l the listener to be removed |
| */ |
| public synchronized <T extends EventListener> void remove(Class<T> t, T l) { |
| if (l ==null) { |
| // In an ideal world, we would do an assertion here |
| // to help developers know they are probably doing |
| // something wrong |
| return; |
| } |
| if (!t.isInstance(l)) { |
| throw new IllegalArgumentException("Listener " + l + |
| " is not of type " + t); |
| } |
| // Is l on the list? |
| int index = -1; |
| for (int i = listenerList.length-2; i>=0; i-=2) { |
| if ((listenerList[i]==t) && (listenerList[i+1].equals(l) == true)) { |
| index = i; |
| break; |
| } |
| } |
| |
| // If so, remove it |
| if (index != -1) { |
| Object[] tmp = new Object[listenerList.length-2]; |
| // Copy the list up to index |
| System.arraycopy(listenerList, 0, tmp, 0, index); |
| // Copy from two past the index, up to |
| // the end of tmp (which is two elements |
| // shorter than the old list) |
| if (index < tmp.length) |
| System.arraycopy(listenerList, index+2, tmp, index, |
| tmp.length - index); |
| // set the listener array to the new array or null |
| listenerList = (tmp.length == 0) ? NULL_ARRAY : tmp; |
| } |
| } |
| |
| // Serialization support. |
| private void writeObject(ObjectOutputStream s) throws IOException { |
| Object[] lList = listenerList; |
| s.defaultWriteObject(); |
| |
| // Save the non-null event listeners: |
| for (int i = 0; i < lList.length; i+=2) { |
| Class<?> t = (Class)lList[i]; |
| EventListener l = (EventListener)lList[i+1]; |
| if ((l!=null) && (l instanceof Serializable)) { |
| s.writeObject(t.getName()); |
| s.writeObject(l); |
| } |
| } |
| |
| s.writeObject(null); |
| } |
| |
| private void readObject(ObjectInputStream s) |
| throws IOException, ClassNotFoundException { |
| listenerList = NULL_ARRAY; |
| s.defaultReadObject(); |
| Object listenerTypeOrNull; |
| |
| while (null != (listenerTypeOrNull = s.readObject())) { |
| ClassLoader cl = Thread.currentThread().getContextClassLoader(); |
| EventListener l = (EventListener)s.readObject(); |
| String name = (String) listenerTypeOrNull; |
| ReflectUtil.checkPackageAccess(name); |
| add((Class<EventListener>)Class.forName(name, true, cl), l); |
| } |
| } |
| |
| /** |
| * Returns a string representation of the EventListenerList. |
| */ |
| public String toString() { |
| Object[] lList = listenerList; |
| String s = "EventListenerList: "; |
| s += lList.length/2 + " listeners: "; |
| for (int i = 0 ; i <= lList.length-2 ; i+=2) { |
| s += " type " + ((Class)lList[i]).getName(); |
| s += " listener " + lList[i+1]; |
| } |
| return s; |
| } |
| } |