The NamingEvent.java Java example source code
/*
* Copyright (c) 1999, 2000, 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
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package javax.naming.event;
import javax.naming.Binding;
/**
* This class represents an event fired by a naming/directory service.
*<p>
* The <tt>NamingEvent's state consists of
* <ul>
* <li>The event source: the EventContext 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
* <em>instance that the listener has registered with.
* Furthermore, the names of the bindings in
* the <tt>NamingEvent are always relative to that instance.
* For example, suppose a listener makes the following registration:
*<blockquote>
* NamespaceChangeListener listener = ...;
* src.addNamingListener("x", SUBTREE_SCOPE, listener);
*</pre>
* When an object named "x/y" is subsequently deleted, the corresponding
* <tt>NamingEvent (evt) must contain:
*<blockquote>
* evt.getEventContext() == src
* evt.getOldBinding().getName().equals("x/y")
*</pre>
*
* Care must be taken when multiple threads are accessing the same
* <tt>EventContext concurrently.
* See the
* <a href=package-summary.html#THREADING>package description
* for more information on threading issues.
*
* @author Rosanna Lee
* @author Scott Seligman
*
* @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.
*/
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.
*/
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 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.
*/
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.
*/
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.
*<p>
* The names in <tt>newBd and oldBd are to be resolved relative
* to the event source <tt>source.
*
* For an <tt>OBJECT_ADDED event type, newBd must not be null.
* For an <tt>OBJECT_REMOVED event type, oldBd must not be null.
* For an <tt>OBJECT_CHANGED event type, newBd and
* <tt>oldBd must not be null. For an OBJECT_RENAMED event type,
* one of <tt>newBd or oldBd 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().
*<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
* are not guaranteed to be thread-safe
* (and <tt>EventContext is a subinterface of Context).
* See the
* <a href=package-summary.html#THREADING>package description
* 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()).
* That is, it must be nonnull for <tt>OBJECT_REMOVED and
* <tt>OBJECT_CHANGED.
* For <tt>OBJECT_RENAMED, 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().
* The object returned by <tt>Binding.getObject() 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()).
* That is, it must be nonnull for <tt>OBJECT_ADDED and
* <tt>OBJECT_CHANGED. For OBJECT_RENAMED,
* 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().
* The object returned by <tt>Binding.getObject() 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, OBJECT_REMOVED,
* <TT>OBJECT_RENAMED, OBJECT_CHANGED.
*<p>
* The listener method is executed in the same thread
* as this method. See the
* <a href=package-summary.html#THREADING>package description
* 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;
}
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