src.com.ibm.as400.vaccess.WorkingEventSupport Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of jt400-jdk8 Show documentation
Show all versions of jt400-jdk8 Show documentation
The Open Source version of the IBM Toolbox for Java
///////////////////////////////////////////////////////////////////////////////
//
// JTOpen (IBM Toolbox for Java - OSS version)
//
// Filename: WorkingEventSupport.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 com.ibm.as400.resource.ActiveStatusEvent; // @C1A
import com.ibm.as400.resource.ActiveStatusListener; // @C1A
import java.util.Vector;
/**
The WorkingEventSupport class represents a list of WorkingListeners.
This implements the WorkingListener interface and will dispatch all
working events that it receives.
**/
//
// Implementation note:
//
// @A1A
// THIS APPLIES TO ALL "EVENT SUPPORT" CLASSES IN THIS PACKAGE:
//
// Class A is defined to fire WorkingEvents. 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 WorkingEventSupport eventSupport_ = new WorkingEventSupport (this);
//
// public void addWorkingListener (WorkingListener listener)
// {
// eventSupport_.addWorkingListener (listener);
// }
//
// public void removeWorkingListener (WorkingListener listener)
// {
// eventSupport_.removeWorkingListener (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 WorkingEvents, and A needs to listen
// to B and refire all WorkingEvents. 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 WorkingEventSupport eventSupport_ = new WorkingEventSupport (this);
//
// public A ()
// {
// b_ = new B ();
// b_.addWorkingListener (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 goes to the system, it will
// fire a WorkingEvent up the chain, so that the top level
// frame can process it and, for example, change its cursor
// to reflect the working state.
//
class WorkingEventSupport
implements WorkingListener, ActiveStatusListener // @C1C
{
private static final String copyright = "Copyright (C) 1997-2000 International Business Machines Corporation and others.";
// Private data.
private transient WorkingListener[] listeners_ = new WorkingListener[0]; // For speed.
private transient Vector listenersV_ = new Vector ();
private Object source_;
/**
Constructs a WorkingEventSupport object.
@param source The source of the events.
**/
public WorkingEventSupport (Object source)
{
source_ = source;
}
/**
Adds a listener.
@param listener The listener.
**/
public void addWorkingListener(WorkingListener listener) {
if (listener == null)
throw new NullPointerException("listener");
synchronized (this) {
listenersV_.addElement(listener);
listeners_ = new WorkingListener[listenersV_.size()];
listenersV_.copyInto(listeners_);
}
}
public void busy(ActiveStatusEvent event) // @C1A
{ // @C1A
fireStartWorking(); // @C1A
} // @C1A
/**
Fires a start working event.
**/
public void fireStartWorking ()
{
// @C2D synchronized (listeners_) {
for (int i = 0; i < listeners_.length; ++i)
listeners_[i].startWorking (new WorkingEvent (source_));
// @C2D }
}
/**
Fires a stop working event.
**/
public void fireStopWorking ()
{
// @C2D synchronized (listeners_) {
for (int i = 0; i < listeners_.length; ++i)
listeners_[i].stopWorking (new WorkingEvent (source_));
// @C2D }
}
public void idle(ActiveStatusEvent event) // @C1A
{ // @C1A
fireStopWorking(); // @C1A
} // @C1A
/**
Removes a listener.
@param listener The listener.
**/
public void removeWorkingListener(WorkingListener listener) {
if (listener == null)
throw new NullPointerException("listener");
synchronized (this) {
if (listenersV_.removeElement(listener)) {
listeners_ = new WorkingListener[listenersV_.size()];
listenersV_.copyInto(listeners_);
}
}
}
/**
Processes a start working event.
@param event The event.
**/
public void startWorking (WorkingEvent event)
{
fireStartWorking ();
}
/**
Processes a stop working event.
@param event The event.
**/
public void stopWorking (WorkingEvent event)
{
fireStopWorking ();
}
}