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Java > Open Source Codes > com > imagero > uio > buffer > RAFBufferRO


1 /*
2  * Copyright (c) Andrey Kuznetsov. All Rights Reserved.
3  *
4  * http://uio.imagero.com
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions are met:
8  *
9  * o Redistributions of source code must retain the above copyright notice,
10  * this list of conditions and the following disclaimer.
11  *
12  * o Redistributions in binary form must reproduce the above copyright notice,
13  * this list of conditions and the following disclaimer in the documentation
14  * and/or other materials provided with the distribution.
15  *
16  * o Neither the name of imagero Andrei Kouznetsov nor the names of
17  * its contributors may be used to endorse or promote products derived
18  * from this software without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
21  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
22  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
23  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
24  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
25  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
26  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
27  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
28  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
29  * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
30  * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31  */
32 package com.imagero.uio.buffer;
33
34 import java.io.IOException JavaDoc;
35 import java.io.RandomAccessFile JavaDoc;
36
37 /**
38  * Implementation of Buffer for RandomAccessRO.
39  *
40  * @author Andrei Kouznetsov
41  * Date: 05.01.2004
42  * Time: 20:59:01
43  */
44 public class RAFBufferRO implements Buffer {
45
46     protected RandomAccessFile JavaDoc raf;
47
48     long offset;
49     int length;
50     byte[] data;
51
52     public RAFBufferRO(RandomAccessFile JavaDoc raf, long offset, int length) {
53         this.raf = raf;
54         if(offset < 0) {
55             throw new IllegalArgumentException JavaDoc("negative offset:" + offset);
56         }
57         this.offset = offset;
58         this.length = length;
59     }
60
61     /**
62      * read specified part of data
63      *
64      * @return data
65      *
66      */
67     public byte[] getData() throws IOException JavaDoc {
68         if(data == null) {
69             readData();
70         }
71         return data;
72     }
73
74     public byte[] getData(byte[] d) throws IOException JavaDoc {
75         if(data == null) {
76             readData();
77         }
78         System.arraycopy(data, 0, d, 0, Math.min(data.length, d.length));
79         return d;
80     }
81
82     public int length() {
83         return length;
84     }
85
86     protected void readData() throws IOException JavaDoc {
87         long currentOffset = raf.getFilePointer();
88         raf.seek(offset);
89         long len = raf.length();
90         int maxlen = (int) Math.min(length, len - offset);
91         if(maxlen < 0) {
92             maxlen = 0;
93         }
94         data = new byte[length];
95         raf.readFully(data, 0, maxlen);
96         raf.seek(currentOffset);
97     }
98
99     public boolean isDirty() {
100         return false;
101     }
102 }
103
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