001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    
018    package org.apache.commons.net.io;
019    
020    import java.util.EventListener;
021    
022    import org.apache.commons.net.util.ListenerList;
023    
024    /**
025     * The CopyStreamAdapter will relay CopyStreamEvents to a list of listeners
026     * when either of its bytesTransferred() methods are called.  Its purpose
027     * is to facilitate the notification of the progress of a copy operation
028     * performed by one of the static copyStream() methods in
029     * org.apache.commons.io.Util to multiple listeners.  The static
030     * copyStream() methods invoke the
031     * bytesTransfered(long, int) of a CopyStreamListener for performance
032     * reasons and also because multiple listeners cannot be registered given
033     * that the methods are static.
034     * <p>
035     * <p>
036     * @see CopyStreamEvent
037     * @see CopyStreamListener
038     * @see Util
039     * @author <a href="mailto:savarese@apache.org">Daniel F. Savarese</a>
040     * @version $Id: CopyStreamAdapter.java 929649 2010-03-31 18:12:07Z sebb $
041     */
042    public class CopyStreamAdapter implements CopyStreamListener
043    {
044        private final ListenerList internalListeners;
045    
046        /**
047         * Creates a new copyStreamAdapter.
048         */
049        public CopyStreamAdapter()
050        {
051            internalListeners = new ListenerList();
052        }
053    
054        /**
055         * This method is invoked by a CopyStreamEvent source after copying
056         * a block of bytes from a stream.  The CopyStreamEvent will contain
057         * the total number of bytes transferred so far and the number of bytes
058         * transferred in the last write.  The CopyStreamAdapater will relay
059         * the event to all of its registered listeners, listing itself as the
060         * source of the event.
061         * @param event The CopyStreamEvent fired by the copying of a block of
062         *              bytes.
063         */
064        public void bytesTransferred(CopyStreamEvent event)
065        {
066            bytesTransferred(event.getTotalBytesTransferred(),
067                             event.getBytesTransferred(),
068                             event.getStreamSize());
069        }
070    
071        /**
072         * This method is not part of the JavaBeans model and is used by the
073         * static methods in the org.apache.commons.io.Util class for efficiency.
074         * It is invoked after a block of bytes to inform the listener of the
075         * transfer.  The CopyStreamAdapater will create a CopyStreamEvent
076         * from the arguments and relay the event to all of its registered
077         * listeners, listing itself as the source of the event.
078         * @param totalBytesTransferred  The total number of bytes transferred
079         *         so far by the copy operation.
080         * @param bytesTransferred  The number of bytes copied by the most recent
081         *          write.
082         * @param streamSize The number of bytes in the stream being copied.
083         *        This may be equal to CopyStreamEvent.UNKNOWN_STREAM_SIZE if
084         *        the size is unknown.
085         */
086        public void bytesTransferred(long totalBytesTransferred,
087                                     int bytesTransferred, long streamSize)
088        {
089            CopyStreamEvent event;
090    
091            event = new CopyStreamEvent(this,
092                                        totalBytesTransferred,
093                                        bytesTransferred,
094                                        streamSize);
095    
096            for (EventListener listener : internalListeners)
097            {
098                ((CopyStreamListener) (listener)).bytesTransferred(event);
099            }
100        }
101    
102        /**
103         * Registers a CopyStreamListener to receive CopyStreamEvents.
104         * Although this method is not declared to be synchronized, it is
105         * implemented in a thread safe manner.
106         * @param listener  The CopyStreamlistener to register.
107         */
108        public void addCopyStreamListener(CopyStreamListener listener)
109        {
110            internalListeners.addListener(listener);
111        }
112    
113        /**
114         * Unregisters a CopyStreamListener.  Although this method is not
115         * synchronized, it is implemented in a thread safe manner.
116         * @param listener  The CopyStreamlistener to unregister.
117         */
118        public void removeCopyStreamListener(CopyStreamListener listener)
119        {
120            internalListeners.removeListener(listener);
121        }
122    }