1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
|
/*
* Copyright 2002-2017 Drew Noakes
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* More information about this project is available at:
*
* https://drewnoakes.com/code/exif/
* https://github.com/drewnoakes/metadata-extractor
*/
package com.drew.lang;
import com.drew.lang.annotations.NotNull;
import java.io.IOException;
import java.io.RandomAccessFile;
/**
* Provides methods to read specific values from a {@link RandomAccessFile}, with a consistent, checked exception structure for
* issues.
*
* @author Drew Noakes https://drewnoakes.com
* */
public class RandomAccessFileReader extends RandomAccessReader
{
@NotNull
private final RandomAccessFile _file;
private final long _length;
private int _currentIndex;
private final int _baseOffset;
@SuppressWarnings({ "ConstantConditions" })
@com.drew.lang.annotations.SuppressWarnings(value = "EI_EXPOSE_REP2", justification = "Design intent")
public RandomAccessFileReader(@NotNull RandomAccessFile file) throws IOException
{
this(file, 0);
}
@SuppressWarnings({ "ConstantConditions" })
@com.drew.lang.annotations.SuppressWarnings(value = "EI_EXPOSE_REP2", justification = "Design intent")
public RandomAccessFileReader(@NotNull RandomAccessFile file, int baseOffset) throws IOException
{
if (file == null)
throw new NullPointerException();
_file = file;
_baseOffset = baseOffset;
_length = _file.length();
}
@Override
public int toUnshiftedOffset(int localOffset)
{
return localOffset + _baseOffset;
}
@Override
public long getLength()
{
return _length;
}
@Override
public byte getByte(int index) throws IOException
{
if (index != _currentIndex)
seek(index);
final int b = _file.read();
if (b < 0)
throw new BufferBoundsException("Unexpected end of file encountered.");
assert (b <= 0xff);
_currentIndex++;
return (byte)b;
}
@Override
@NotNull
public byte[] getBytes(int index, int count) throws IOException
{
validateIndex(index, count);
if (index != _currentIndex)
seek(index);
byte[] bytes = new byte[count];
final int bytesRead = _file.read(bytes);
_currentIndex += bytesRead;
if (bytesRead != count)
throw new BufferBoundsException("Unexpected end of file encountered.");
return bytes;
}
private void seek(final int index) throws IOException
{
if (index == _currentIndex)
return;
_file.seek(index);
_currentIndex = index;
}
@Override
protected boolean isValidIndex(int index, int bytesRequested) throws IOException
{
return bytesRequested >= 0
&& index >= 0
&& (long)index + (long)bytesRequested - 1L < _length;
}
@Override
protected void validateIndex(final int index, final int bytesRequested) throws IOException
{
if (!isValidIndex(index, bytesRequested))
throw new BufferBoundsException(index, bytesRequested, _length);
}
}
|
