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


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 com.imagero.uio.RandomAccessRO;
35
36 import java.io.IOException JavaDoc;
37
38 /**
39  * Implementation of Buffer for RandomAccessRO.
40  *
41  * @author Andrei Kouznetsov
42  * Date: 05.01.2004
43  * Time: 20:59:01
44  */
45 public class RABufferRO implements Buffer {
46
47     RandomAccessRO ro;
48
49     long offset;
50     int length;
51     byte[] data;
52
53     public RABufferRO(RandomAccessRO ro, long offset, int length) {
54         this.ro = ro;
55         this.offset = offset;
56         this.length = length;
57     }
58
59     /**
60      * getData
61      *
62      * @return data
63      */
64     public byte[] getData() throws IOException JavaDoc {
65         if(data == null) {
66             readData();
67         }
68         return data;
69     }
70
71     public byte[] getData(byte[] d) throws IOException JavaDoc {
72         if(data == null) {
73             readData();
74         }
75         System.arraycopy(data, 0, d, 0, Math.min(data.length, d.length));
76         return d;
77     }
78
79     public int length() {
80         return length;
81     }
82
83     private void readData() throws IOException JavaDoc {
84         long currentOffset = ro.getFilePointer();
85         ro.seek(offset);
86         long len = ro.length();
87         int maxlen = (int) Math.min(length, len - offset);
88         if(maxlen < 0) {
89             maxlen = 0;
90         }
91         data = new byte[length];
92         ro.readFully(data, 0, maxlen);
93         ro.seek(currentOffset);
94     }
95
96     public boolean isDirty() {
97         return false;
98     }
99 }
100
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