src.com.ibm.as400.vaccess.VObjectEventSupport Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of jt400-jdk6 Show documentation
Show all versions of jt400-jdk6 Show documentation
The Open Source version of the IBM Toolbox for Java
///////////////////////////////////////////////////////////////////////////////
//
// JTOpen (IBM Toolbox for Java - OSS version)
//
// Filename: VObjectEventSupport.java
//
// The source code contained herein is licensed under the IBM Public License
// Version 1.0, which has been approved by the Open Source Initiative.
// Copyright (C) 1997-2000 International Business Machines Corporation and
// others. All rights reserved.
//
///////////////////////////////////////////////////////////////////////////////
package com.ibm.as400.vaccess;
import java.util.Vector;
/**
The VObjectEventSupport class represents a list of VObjectListeners.
This is also a VObjectListener and will dispatch all VObjectEvents
that it receives.
**/
//
// Implementation note:
//
// THIS APPLIES TO ALL "EVENT SUPPORT" CLASSES IN THIS PACKAGE:
//
// Class A is defined to fire VObjectEvents. As a result, it
// has to maintain a list of the listeners. Since many classes
// in the package have to do this, we provide an "event support"
// class to maintain this list. This is patterened after
// the java.beans.PropertyChangeSupport class provided in the JDK.
//
// public class A
// {
// private VObjectEventSupport eventSupport_ = new VObjectEventSupport (this);
//
// public void addVObjectListener (VObjectListener listener)
// {
// eventSupport_.addVObjectListener (listener);
// }
//
// public void removeVObjectListener (VObjectListener listener)
// {
// eventSupport_.removeVObjectListener (listener);
// }
//
// public void someMethod ()
// {
// ... some code here ...
// eventSupport_.fireObjectChanged (anObject);
// ... some more code here ...
// }
// }
//
// There is another case where class A contains a private instance
// of class B. B fires VObjectEvents, and A needs to listen
// to B and refire all VObjectEvents. In addition, it needs
// to change the source of the event so that it looks like
// A is the source, even though B is the real source. The
// reason for this is that listeners have public access to the
// source of the event, and we don't want them to have access to B.
//
// This is all easy to accompilsh by simply adding the
// event support object as a listener to B. The event
// support object takes care of the rest.
//
// public class A
// {
// private B b_;
// private VObjectEventSupport eventSupport_ = new VObjectEventSupport (this);
//
// public A ()
// {
// b_ = new B ();
// b_.addVObjectListener (eventSupport_);
// }
// }
//
// This type of event dispatching happens all over in the
// vaccess package. This is because of the hierarchy of
// components. Consider an explorer pane that presents
// a view of a directory structure. Here is the hierarchy:
//
// AS400ExplorerPane
// |
// +-- AS400TreePane
// | |
// | +-- AS400TreeModel
// | |
// | +-- VIFSDirectory (root directory) <-----------+
// | | |
// | +-- VIFSDirectory (subdirectory) |
// | | | |
// | | +-- VIFSFile (file in subdirectory) |
// | | |
// | +-- VIFSFile (file in root directory) |
// | |
// +-- AS400DetailsPane |
// | |
// +-- AS400DetailsModel |
// | |
// +----------------------------------------------+
//
// If any object fires certain events, then all objects
// above them in the hierarchy need to hear about it. Rather
// than making all objects specifically listen to all objects
// below them, we just make them listen to the objects
// directly below them. Then they "bubble" (dispatch) them
// up the chain to the parent. All nodes in between can process
// them on the way up.
//
// Now, when one of the VIFSFile's is deleted, it will
// fire a VObjectEvent up the chain, so that:
//
// 1. The VIFSDirectory can modify its list of children.
// 2. The AS400TreeModel can remove the file from the model.
// 3. The AS400TreePane can update its view.
// 4. The AS400DetailsModel can remove the file from the model.
// 5. The AS400DetailsPane can update its view.
// 6. The AS400ExplorerPane can refire the event to its listeners.
// 7. The caller (application) can process it.
//
class VObjectEventSupport
implements VObjectListener
{
private static final String copyright = "Copyright (C) 1997-2000 International Business Machines Corporation and others.";
// Private data.
private transient VObjectListener[] listeners_ = new VObjectListener[0]; // For speed.
private transient Vector listenersV_ = new Vector ();
private Object source_;
/**
Constructs a VObjectEventSupport object.
@param source The source of the events.
**/
public VObjectEventSupport (Object source)
{
source_ = source;
}
/**
* Adds a listener.
*
* @param listener
* The listener.
**/
public void addVObjectListener(VObjectListener listener) {
if (listener == null)
throw new NullPointerException("listener");
synchronized (this) {
listenersV_.addElement(listener);
listeners_ = new VObjectListener[listenersV_.size()];
listenersV_.copyInto(listeners_);
}
}
/**
Fires an object changed event.
@param object The object.
**/
public void fireObjectChanged (VObject object)
{
fireObjectChanged (new VObjectEvent (source_, object));
}
// @A1A
public void fireObjectChanged (VObject object, boolean duringLoad)
{
fireObjectChanged (new VObjectEvent (source_, object, duringLoad));
}
/**
Fires an object changed event.
@param event The event.
**/
public void fireObjectChanged (VObjectEvent event)
{
synchronized (listeners_) {
for (int i = 0; i < listeners_.length; ++i)
listeners_[i].objectChanged (event);
}
}
/**
Fires an object created event.
@param object The object.
**/
public void fireObjectCreated (VObject object)
{
fireObjectCreated (new VObjectEvent (source_, object));
}
/**
Fires an object created event.
@param object The object.
@param parent The parent.
**/
public void fireObjectCreated (VObject object, VNode parent)
{
fireObjectCreated (new VObjectEvent (source_, object, parent));
}
/**
Fires an object created event.
@param event The event.
**/
public void fireObjectCreated (VObjectEvent event)
{
synchronized (listeners_) {
for (int i = 0; i < listeners_.length; ++i)
listeners_[i].objectCreated (event);
}
}
/**
Fires an object deleted event.
@param object The object.
**/
public void fireObjectDeleted (VObject object)
{
fireObjectDeleted (new VObjectEvent (source_, object));
}
/**
Fires an object deleted event.
@param event The event.
**/
public void fireObjectDeleted (VObjectEvent event)
{
synchronized (listeners_) {
for (int i = 0; i < listeners_.length; ++i)
listeners_[i].objectDeleted (event);
}
}
/**
Processes object created events.
@param event The event.
**/
public void objectCreated (VObjectEvent event)
{
fireObjectCreated (event);
}
/**
Processes object changed events.
@param event The event.
**/
public void objectChanged (VObjectEvent event)
{
fireObjectChanged (event);
}
/**
Processes object deleted events.
@param event The event.
**/
public void objectDeleted (VObjectEvent event)
{
fireObjectDeleted (event);
}
/**
Removes a listener.
@param listener The listener.
**/
public void removeVObjectListener(VObjectListener listener) {
if (listener == null)
throw new NullPointerException("listener");
synchronized (this) {
if (listenersV_.removeElement(listener)) {
listeners_ = new VObjectListener[listenersV_.size()];
listenersV_.copyInto(listeners_);
}
}
}
}