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Java > Open Source Codes > com > imagero > uio > OffsetRandomAccessFile


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;
33
34 import java.io.File JavaDoc;
35 import java.io.IOException JavaDoc;
36 import java.io.RandomAccessFile JavaDoc;
37
38 /**
39  * OffsetRandomAccessFile.java
40  * <br>
41  * Usefull for reading EXIF files<br>
42  * However this class has bad performance, bacause the data is unbuffered.
43  *
44  * @author Andrei Kouznetsov
45  */
46 public class OffsetRandomAccessFile extends RandomAccessFile JavaDoc {
47     protected long offset;
48     protected long length;
49
50     public OffsetRandomAccessFile(File JavaDoc file, String JavaDoc mode, long offset) throws IOException JavaDoc {
51         this(file, mode, offset, file.length() - offset);
52     }
53
54     public OffsetRandomAccessFile(File JavaDoc file, String JavaDoc mode, long offset, long length) throws IOException JavaDoc {
55         super(file, mode);
56         this.offset = offset;
57         this.length = length;
58         seek(0);
59     }
60
61     public OffsetRandomAccessFile(String JavaDoc name, String JavaDoc mode, long offset) throws IOException JavaDoc {
62         this(new File JavaDoc(name), mode, offset);
63     }
64
65     public OffsetRandomAccessFile(String JavaDoc name, String JavaDoc mode, long offset, long length) throws IOException JavaDoc {
66         this(new File JavaDoc(name), mode, offset, length);
67     }
68
69     public void seek(long pos) throws IOException JavaDoc {
70         if(pos < 0) {
71             throw new IOException JavaDoc();
72         }
73         super.seek(pos + offset);
74     }
75
76     public int read() throws IOException JavaDoc {
77         if(getFilePointer() >= length) {
78             return -1;
79         }
80         return super.read();
81     }
82
83     public long length() throws IOException JavaDoc {
84         return length;
85     }
86
87     public long getFilePointer() throws IOException JavaDoc {
88         return super.getFilePointer() - offset;
89     }
90
91     public int skip(int n) throws IOException JavaDoc {
92         return skipBytes(n);
93     }
94 }
95
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