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Java > Open Source Codes > org > jboss > util > stream > NotifyingBufferedOutputStream


1 /*
2   * JBoss, Home of Professional Open Source
3   * Copyright 2005, JBoss Inc., and individual contributors as indicated
4   * by the @authors tag. See the copyright.txt in the distribution for a
5   * full listing of individual contributors.
6   *
7   * This is free software; you can redistribute it and/or modify it
8   * under the terms of the GNU Lesser General Public License as
9   * published by the Free Software Foundation; either version 2.1 of
10   * the License, or (at your option) any later version.
11   *
12   * This software is distributed in the hope that it will be useful,
13   * but WITHOUT ANY WARRANTY; without even the implied warranty of
14   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15   * Lesser General Public License for more details.
16   *
17   * You should have received a copy of the GNU Lesser General Public
18   * License along with this software; if not, write to the Free
19   * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
20   * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
21   */
22 package org.jboss.util.stream;
23
24 import java.io.BufferedOutputStream JavaDoc;
25 import java.io.IOException JavaDoc;
26 import java.io.OutputStream JavaDoc;
27
28 /**
29  * A buffered output stream that notifies every "chunk"
30  *
31  * @version <tt>$Revision: 1958 $</tt>
32  * @author <a HREF="mailto:Adrian@jboss.org">Adrian Brock</a>
33  */
34 public class NotifyingBufferedOutputStream
35    extends BufferedOutputStream JavaDoc
36 {
37    /**
38     * The number of bytes between notifications
39     */
40    int chunkSize;
41
42    /**
43     * The number of bytes written in the current chunk
44     */
45    int chunk = 0;
46
47    /**
48     * The listener notified every chunk
49     */
50    StreamListener listener;
51
52    /**
53     * Construct a notifying buffered outputstream.<br>
54     * The listener is notified once every chunk.
55     *
56     * @param os the output stream to be buffered
57     * @param size the buffer size
58     * @param chunkSize the chunk size
59     * @exception IllegalArgumentException for a size <= 0 or chunkSize <= size or a null listener
60     */
61    public NotifyingBufferedOutputStream(OutputStream JavaDoc os, int size, int chunkSize, StreamListener listener)
62    {
63       super(os, size);
64       if (chunkSize <= size)
65          throw new IllegalArgumentException JavaDoc("chunkSize must be bigger than the buffer");
66       this.chunkSize = chunkSize;
67       this.listener = listener;
68    }
69
70    public void setStreamListener(StreamListener listener)
71    {
72       this.listener = listener;
73    }
74
75    public void write(int b)
76       throws IOException JavaDoc
77    {
78       super.write(b);
79       checkNotification(1);
80    }
81
82    public void write(byte[] b, int off, int len)
83       throws IOException JavaDoc
84    {
85       super.write(b, off, len);
86       checkNotification(len);
87    }
88
89    /**
90     * Checks whether a notification is required and
91     * notifies as appropriate
92     *
93     * @param result the number of bytes written
94     */
95    public void checkNotification(int result)
96    {
97       // Is a notification required?
98 chunk += result;
99       if (chunk >= chunkSize)
100       {
101          if (listener != null)
102             listener.onStreamNotification(this, chunk);
103
104          // Start a new chunk
105 chunk = 0;
106       }
107    }
108 }
109
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