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/*******************************************************************************
* Copyright (c) 2000, 2004 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Common Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/cpl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.compare;
import java.io.*;
import org.eclipse.jface.util.ListenerList;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.compare.internal.Utilities;
/**
* Abstract implementation for a buffered <code>IStreamContentAccessor</code>.
* <p>
* Subclasses must implement the <code>createStream</code> method
* to connect the buffered content with a streamable source (e.g., a file).
* <p>
* As long as the contents of <code>BufferedContent</code> is only retrieved as an input stream
* (by means of <code>getContents</code>) and the <code>BufferedContent</code> is not modified (with
* <code>setContent</code>) no buffering takes place.
* Buffering starts when either method <code>getContent</code> or <code>setContent</code> is called.
*
* @see IContentChangeNotifier
* @see IStreamContentAccessor
*/
public abstract class BufferedContent implements IContentChangeNotifier, IStreamContentAccessor {
byte[] fContent;
private ListenerList fListenerList;
/**
* Creates a buffered stream content accessor.
*/
protected BufferedContent() {
}
/* (non-Javadoc)
* see IStreamContentAccessor.getContents
*/
public InputStream getContents() throws CoreException {
if (fContent != null)
return new ByteArrayInputStream(fContent);
return createStream();
}
/**
* Creates and returns a stream for reading the contents.
* <p>
* Subclasses must implement this method.
* </p>
*
* @return the stream from which the content is read
* @exception CoreException if the contents could not be accessed
*/
protected abstract InputStream createStream() throws CoreException;
/**
* Sets the contents. Registered content change listeners are notified.
*
* @param contents the new contents
*/
public void setContent(byte[] contents) {
fContent= contents;
fireContentChanged();
}
/**
* Returns the contents as an array of bytes.
*
* @return the contents as an array of bytes, or <code>null</code> if
* the contents could not be accessed
*/
public byte[] getContent() {
if (fContent == null) {
try {
InputStream is= createStream();
fContent= Utilities.readBytes(is);
} catch(CoreException ex) {
// NeedWork
}
}
return fContent;
}
/**
* Discards the buffered content.
*/
public void discardBuffer() {
fContent= null;
}
/* (non-Javadoc)
* see IContentChangeNotifier.addChangeListener
*/
public void addContentChangeListener(IContentChangeListener listener) {
if (fListenerList == null)
fListenerList= new ListenerList();
fListenerList.add(listener);
}
/* (non-Javadoc)
* see IContentChangeNotifier.removeChangeListener
*/
public void removeContentChangeListener(IContentChangeListener listener) {
if (fListenerList != null) {
fListenerList.remove(listener);
if (fListenerList.isEmpty())
fListenerList= null;
}
}
/**
* Notifies all registered <code>IContentChangeListener</code>s of a content change.
*/
protected void fireContentChanged() {
if (fListenerList != null) {
Object[] listeners= fListenerList.getListeners();
for (int i= 0; i < listeners.length; i++)
((IContentChangeListener)listeners[i]).contentChanged(this);
}
}
}
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