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ChangeListenerMap.java
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241 lines (226 loc) · 6.88 KB
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/*
* Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package java.beans;
import java.util.ArrayList;
import java.util.Collections;
import java.util.EventListener;
import java.util.EventListenerProxy;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
/**
* This is an abstract class that provides base functionality
* for the {@link PropertyChangeSupport PropertyChangeSupport} class
* and the {@link VetoableChangeSupport VetoableChangeSupport} class.
*
* @see PropertyChangeListenerMap
* @see VetoableChangeListenerMap
*
* @author Sergey A. Malenkov
*/
abstract class ChangeListenerMap<L extends EventListener> {
private Map<String, L[]> map;
/**
* Creates an array of listeners.
* This method can be optimized by using
* the same instance of the empty array
* when {@code length} is equal to {@code 0}.
*
* @param length the array length
* @return an array with specified length
*/
protected abstract L[] newArray(int length);
/**
* Creates a proxy listener for the specified property.
*
* @param name the name of the property to listen on
* @param listener the listener to process events
* @return a proxy listener
*/
protected abstract L newProxy(String name, L listener);
/**
* Adds a listener to the list of listeners for the specified property.
* This listener is called as many times as it was added.
*
* @param name the name of the property to listen on
* @param listener the listener to process events
*/
public final synchronized void add(String name, L listener) {
if (this.map == null) {
this.map = new HashMap<>();
}
L[] array = this.map.get(name);
int size = (array != null)
? array.length
: 0;
L[] clone = newArray(size + 1);
clone[size] = listener;
if (array != null) {
System.arraycopy(array, 0, clone, 0, size);
}
this.map.put(name, clone);
}
/**
* Removes a listener from the list of listeners for the specified property.
* If the listener was added more than once to the same event source,
* this listener will be notified one less time after being removed.
*
* @param name the name of the property to listen on
* @param listener the listener to process events
*/
public final synchronized void remove(String name, L listener) {
if (this.map != null) {
L[] array = this.map.get(name);
if (array != null) {
for (int i = 0; i < array.length; i++) {
if (listener.equals(array[i])) {
int size = array.length - 1;
if (size > 0) {
L[] clone = newArray(size);
System.arraycopy(array, 0, clone, 0, i);
System.arraycopy(array, i + 1, clone, i, size - i);
this.map.put(name, clone);
}
else {
this.map.remove(name);
if (this.map.isEmpty()) {
this.map = null;
}
}
break;
}
}
}
}
}
/**
* Returns the list of listeners for the specified property.
*
* @param name the name of the property
* @return the corresponding list of listeners
*/
public final synchronized L[] get(String name) {
return (this.map != null)
? this.map.get(name)
: null;
}
/**
* Sets new list of listeners for the specified property.
*
* @param name the name of the property
* @param listeners new list of listeners
*/
public final void set(String name, L[] listeners) {
if (listeners != null) {
if (this.map == null) {
this.map = new HashMap<>();
}
this.map.put(name, listeners);
}
else if (this.map != null) {
this.map.remove(name);
if (this.map.isEmpty()) {
this.map = null;
}
}
}
/**
* Returns all listeners in the map.
*
* @return an array of all listeners
*/
public final synchronized L[] getListeners() {
if (this.map == null) {
return newArray(0);
}
List<L> list = new ArrayList<>();
L[] listeners = this.map.get(null);
if (listeners != null) {
for (L listener : listeners) {
list.add(listener);
}
}
for (Entry<String, L[]> entry : this.map.entrySet()) {
String name = entry.getKey();
if (name != null) {
for (L listener : entry.getValue()) {
list.add(newProxy(name, listener));
}
}
}
return list.toArray(newArray(list.size()));
}
/**
* Returns listeners that have been associated with the named property.
*
* @param name the name of the property
* @return an array of listeners for the named property
*/
public final L[] getListeners(String name) {
if (name != null) {
L[] listeners = get(name);
if (listeners != null) {
return listeners.clone();
}
}
return newArray(0);
}
/**
* Indicates whether the map contains
* at least one listener to be notified.
*
* @param name the name of the property
* @return {@code true} if at least one listener exists or
* {@code false} otherwise
*/
public final synchronized boolean hasListeners(String name) {
if (this.map == null) {
return false;
}
L[] array = this.map.get(null);
return (array != null) || ((name != null) && (null != this.map.get(name)));
}
/**
* Returns a set of entries from the map.
* Each entry is a pair consisted of the property name
* and the corresponding list of listeners.
*
* @return a set of entries from the map
*/
public final Set<Entry<String, L[]>> getEntries() {
return (this.map != null)
? this.map.entrySet()
: Collections.<Entry<String, L[]>>emptySet();
}
/**
* Extracts a real listener from the proxy listener.
* It is necessary because default proxy class is not serializable.
*
* @return a real listener
*/
public abstract L extract(L listener);
}