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Panda Core is the core module of Panda Framework, it contains commonly used utility classes similar to apache-commons.
There is a newer version: 1.8.0
package panda.net.io;

import java.util.EventListener;

import panda.net.util.ListenerList;

/**
 * The CopyStreamAdapter will relay CopyStreamEvents to a list of listeners when either of its
 * bytesTransferred() methods are called. Its purpose is to facilitate the notification of the
 * progress of a copy operation performed by one of the static copyStream() methods in
 * org.apache.commons.io.Util to multiple listeners. The static copyStream() methods invoke the
 * bytesTransfered(long, int) of a CopyStreamListener for performance reasons and also because
 * multiple listeners cannot be registered given that the methods are static.
 * 
 * @see CopyStreamEvent
 * @see CopyStreamListener
 * @see Util
 */
public class CopyStreamAdapter implements CopyStreamListener {
	private final ListenerList internalListeners;

	/**
	 * Creates a new copyStreamAdapter.
	 */
	public CopyStreamAdapter() {
		internalListeners = new ListenerList();
	}

	/**
	 * This method is invoked by a CopyStreamEvent source after copying a block of bytes from a
	 * stream. The CopyStreamEvent will contain the total number of bytes transferred so far and the
	 * number of bytes transferred in the last write. The CopyStreamAdapater will relay the event to
	 * all of its registered listeners, listing itself as the source of the event.
	 * 
	 * @param event The CopyStreamEvent fired by the copying of a block of bytes.
	 */
	// @Override
	public void bytesTransferred(CopyStreamEvent event) {
		for (EventListener listener : internalListeners) {
			((CopyStreamListener)(listener)).bytesTransferred(event);
		}
	}

	/**
	 * This method is not part of the JavaBeans model and is used by the static methods in the
	 * org.apache.commons.io.Util class for efficiency. It is invoked after a block of bytes to
	 * inform the listener of the transfer. The CopyStreamAdapater will create a CopyStreamEvent
	 * from the arguments and relay the event to all of its registered listeners, listing itself as
	 * the source of the event.
	 * 
	 * @param totalBytesTransferred The total number of bytes transferred so far by the copy
	 *            operation.
	 * @param bytesTransferred The number of bytes copied by the most recent write.
	 * @param streamSize The number of bytes in the stream being copied. This may be equal to
	 *            CopyStreamEvent.UNKNOWN_STREAM_SIZE if the size is unknown.
	 */
	// @Override
	public void bytesTransferred(long totalBytesTransferred, int bytesTransferred, long streamSize) {
		for (EventListener listener : internalListeners) {
			((CopyStreamListener)(listener)).bytesTransferred(totalBytesTransferred, bytesTransferred, streamSize);
		}
	}

	/**
	 * Registers a CopyStreamListener to receive CopyStreamEvents. Although this method is not
	 * declared to be synchronized, it is implemented in a thread safe manner.
	 * 
	 * @param listener The CopyStreamlistener to register.
	 */
	public void addCopyStreamListener(CopyStreamListener listener) {
		internalListeners.addListener(listener);
	}

	/**
	 * Unregisters a CopyStreamListener. Although this method is not synchronized, it is implemented
	 * in a thread safe manner.
	 * 
	 * @param listener The CopyStreamlistener to unregister.
	 */
	public void removeCopyStreamListener(CopyStreamListener listener) {
		internalListeners.removeListener(listener);
	}
}