/*
 * Copyright 2001-2004 The Apache Software Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.net.io;
import java.util.EventListener;

/**
 * The CopyStreamListener class can accept CopyStreamEvents to keep track
 * of the progress of a stream copying operation.  However, it is currently
 * not used that way within NetComponents for performance reasons.  Rather
 * the bytesTransferred(long, int) method is called directly rather than
 * passing an event to bytesTransferred(CopyStreamEvent), saving the creation
 * of a CopyStreamEvent instance.  Also, the only place where
 * CopyStreamListener is currently used within NetComponents is in the
 * static methods of the uninstantiable org.apache.commons.io.Util class, which
 * would preclude the use of addCopyStreamListener and
 * removeCopyStreamListener methods.  However, future additions may use the
 * JavaBean event model, which is why the hooks have been included from the
 * beginning.
 * 

 * 

 * @see CopyStreamEvent
 * @see CopyStreamAdapter
 * @see Util
 * @author Daniel F. Savarese
 * @version $Id: CopyStreamListener.java,v 1.9 2004/02/29 10:26:55 scolebourne Exp $
 */
public interface CopyStreamListener extends EventListener
{
    /**
     * 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.
     * @param event The CopyStreamEvent fired by the copying of a block of
     *              bytes.
     */
    public void bytesTransferred(CopyStreamEvent 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.
     * @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.
     */
    public void bytesTransferred(long totalBytesTransferred,
                                 int bytesTransferred,
                                 long streamSize);
}