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/* * @(#)NamingEvent.java 1.11 05/11/17 * * Copyright 2006 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */ package javax.naming.event; import javax.naming.Binding; /** * This class represents an event fired by a naming/directory service. *<p> * The <tt>NamingEvent</tt>'s state consists of * <ul> * <li>The event source: the <tt>EventContext</tt> which fired this event. * <li>The event type. * <li>The new binding: information about the object after the change. * <li>The old binding: information about the object before the change. * <li>Change information: information about the change * that triggered this event; usually service provider-specific or server-specific * information. * </ul> * <p> * Note that the event source is always the same <tt>EventContext</tt> * <em>instance</em> that the listener has registered with. * Furthermore, the names of the bindings in * the <tt>NamingEvent</tt> are always relative to that instance. * For example, suppose a listener makes the following registration: *<blockquote><pre> * NamespaceChangeListener listener = ...; * src.addNamingListener("x", SUBTREE_SCOPE, listener); *</pre></blockquote> * When an object named "x/y" is subsequently deleted, the corresponding * <tt>NamingEvent</tt> (<tt>evt</tt>) must contain: *<blockquote><pre> * evt.getEventContext() == src * evt.getOldBinding().getName().equals("x/y") *</pre></blockquote> * * Care must be taken when multiple threads are accessing the same * <tt>EventContext</tt> concurrently. * See the * <a href=package-summary.html#THREADING>package description</a> * for more information on threading issues. * * @author Rosanna Lee * @author Scott Seligman * @version 1.11 05/11/17 * * @see NamingListener * @see EventContext * @since 1.3 */ public class NamingEvent extends java.util.EventObject { /** * Naming event type for indicating that a new object has been added. * The value of this constant is <tt>0</tt>. */ public static final int OBJECT_ADDED = 0; /** * Naming event type for indicating that an object has been removed. * The value of this constant is <tt>1</tt>. */ public static final int OBJECT_REMOVED = 1; /** * Naming event type for indicating that an object has been renamed. * Note that some services might fire multiple events for a single * logical rename operation. For example, the rename operation might * be implemented by adding a binding with the new name and removing * the old binding. *<p> * The old/new binding in <tt>NamingEvent</tt> may be null if the old * name or new name is outside of the scope for which the listener * has registered. *<p> * When an interior node in the namespace tree has been renamed, the * topmost node which is part of the listener's scope should used to generate * a rename event. The extent to which this can be supported is * provider-specific. For example, a service might generate rename * notifications for all descendants of the changed interior node and the * corresponding provider might not be able to prevent those * notifications from being propagated to the listeners. *<p> * The value of this constant is <tt>2</tt>. */ public static final int OBJECT_RENAMED = 2; /** * Naming event type for indicating that an object has been changed. * The changes might include the object's attributes, or the object itself. * Note that some services might fire multiple events for a single * modification. For example, the modification might * be implemented by first removing the old binding and adding * a new binding containing the same name but a different object. *<p> * The value of this constant is <tt>3</tt>. */ public static final int OBJECT_CHANGED = 3; /** * Contains information about the change that generated this event. * @serial */ protected Object changeInfo; /** * Contains the type of this event. * @see #OBJECT_ADDED * @see #OBJECT_REMOVED * @see #OBJECT_RENAMED * @see #OBJECT_CHANGED * @serial */ protected int type; /** * Contains information about the object before the change. * @serial */ protected Binding oldBinding; /** * Contains information about the object after the change. * @serial */ protected Binding newBinding; /** * Constructs an instance of <tt>NamingEvent</tt>. *<p> * The names in <tt>newBd</tt> and <tt>oldBd</tt> are to be resolved relative * to the event source <tt>source</tt>. * * For an <tt>OBJECT_ADDED</tt> event type, <tt>newBd</tt> must not be null. * For an <tt>OBJECT_REMOVED</tt> event type, <tt>oldBd</tt> must not be null. * For an <tt>OBJECT_CHANGED</tt> event type, <tt>newBd</tt> and * <tt>oldBd</tt> must not be null. For an <tt>OBJECT_RENAMED</tt> event type, * one of <tt>newBd</tt> or <tt>oldBd</tt> may be null if the new or old * binding is outside of the scope for which the listener has registered. * * @param source The non-null context that fired this event. * @param type The type of the event. * @param newBd A possibly null binding before the change. See method description. * @param oldBd A possibly null binding after the change. See method description. * @param changeInfo A possibly null object containing information about the change. * @see #OBJECT_ADDED * @see #OBJECT_REMOVED * @see #OBJECT_RENAMED * @see #OBJECT_CHANGED */ public NamingEvent(EventContext source, int type, Binding newBd, Binding oldBd, Object changeInfo) { super(source); this.type = type; oldBinding = oldBd; newBinding = newBd; this.changeInfo = changeInfo; } /** * Returns the type of this event. * @return The type of this event. * @see #OBJECT_ADDED * @see #OBJECT_REMOVED * @see #OBJECT_RENAMED * @see #OBJECT_CHANGED */ public int getType() { return type; } /** * Retrieves the event source that fired this event. * This returns the same object as <tt>EventObject.getSource()</tt>. *<p> * If the result of this method is used to access the * event source, for example, to look up the object or get its attributes, * then it needs to be locked because implementations of <tt>Context</tt> * are not guaranteed to be thread-safe * (and <tt>EventContext</tt> is a subinterface of <tt>Context</tt>). * See the * <a href=package-summary.html#THREADING>package description</a> * for more information on threading issues. * * @return The non-null context that fired this event. */ public EventContext getEventContext() { return (EventContext)getSource(); } /** * Retrieves the binding of the object before the change. *<p> * The binding must be nonnull if the object existed before the change * relative to the source context (<tt>getEventContext()</tt>). * That is, it must be nonnull for <tt>OBJECT_REMOVED</tt> and * <tt>OBJECT_CHANGED</tt>. * For <tt>OBJECT_RENAMED</tt>, it is null if the object before the rename * is outside of the scope for which the listener has registered interest; * it is nonnull if the object is inside the scope before the rename. *<p> * The name in the binding is to be resolved relative * to the event source <tt>getEventContext()</tt>. * The object returned by <tt>Binding.getObject()</tt> may be null if * such information is unavailable. * * @return The possibly null binding of the object before the change. */ public Binding getOldBinding() { return oldBinding; } /** * Retrieves the binding of the object after the change. *<p> * The binding must be nonnull if the object existed after the change * relative to the source context (<tt>getEventContext()</tt>). * That is, it must be nonnull for <tt>OBJECT_ADDED</tt> and * <tt>OBJECT_CHANGED</tt>. For <tt>OBJECT_RENAMED</tt>, * it is null if the object after the rename is outside the scope for * which the listener registered interest; it is nonnull if the object * is inside the scope after the rename. *<p> * The name in the binding is to be resolved relative * to the event source <tt>getEventContext()</tt>. * The object returned by <tt>Binding.getObject()</tt> may be null if * such information is unavailable. * * @return The possibly null binding of the object after the change. */ public Binding getNewBinding() { return newBinding; } /** * Retrieves the change information for this event. * The value of the change information is service-specific. For example, * it could be an ID that identifies the change in a change log on the server. * * @return The possibly null change information of this event. */ public Object getChangeInfo() { return changeInfo; } /** * Invokes the appropriate listener method on this event. * The default implementation of * this method handles the following event types: * <tt>OBJECT_ADDED</TT>, <TT>OBJECT_REMOVED</TT>, * <TT>OBJECT_RENAMED</TT>, <TT>OBJECT_CHANGED</TT>. *<p> * The listener method is executed in the same thread * as this method. See the * <a href=package-summary.html#THREADING>package description</a> * for more information on threading issues. * @param listener The nonnull listener. */ public void dispatch(NamingListener listener) { switch (type) { case OBJECT_ADDED: ((NamespaceChangeListener)listener).objectAdded(this); break; case OBJECT_REMOVED: ((NamespaceChangeListener)listener).objectRemoved(this); break; case OBJECT_RENAMED: ((NamespaceChangeListener)listener).objectRenamed(this); break; case OBJECT_CHANGED: ((ObjectChangeListener)listener).objectChanged(this); break; } } private static final long serialVersionUID = -7126752885365133499L; }