RandomAccessFileInputStream.java revision 5ff4ee9a3fc898dbe9a67386e984f14c21338391 
1/*
2 * Copyright 2013, Google Inc.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are
7 * met:
8 *
9 *     * Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 *     * Redistributions in binary form must reproduce the above
12 * copyright notice, this list of conditions and the following disclaimer
13 * in the documentation and/or other materials provided with the
14 * distribution.
15 *     * Neither the name of Google Inc. nor the names of its
16 * contributors may be used to endorse or promote products derived from
17 * this software without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
20 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
21 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
22 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
23 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
24 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
25 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
29 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 */
31
32package org.jf.util;
33
34import javax.annotation.Nonnull;
35import java.io.IOException;
36import java.io.InputStream;
37import java.io.RandomAccessFile;
38
39public class RandomAccessFileInputStream extends InputStream {
40    private int filePosition;
41    @Nonnull private final RandomAccessFile raf;
42
43    public RandomAccessFileInputStream(@Nonnull RandomAccessFile raf, int filePosition) {
44        this.filePosition = filePosition;
45        this.raf = raf;
46    }
47
48    @Override public int read() throws IOException {
49        raf.seek(filePosition);
50        filePosition++;
51        return raf.read();
52    }
53
54    @Override public int read(byte[] bytes) throws IOException {
55        raf.seek(filePosition);
56        int bytesRead = raf.read(bytes);
57        filePosition += bytesRead;
58        return bytesRead;
59    }
60
61    @Override public int read(byte[] bytes, int offset, int length) throws IOException {
62        raf.seek(filePosition);
63        int bytesRead = raf.read(bytes, offset, length);
64        filePosition += bytesRead;
65        return bytesRead;
66    }
67
68    @Override public long skip(long l) throws IOException {
69        int skipBytes = Math.min((int)l, available());
70        filePosition += skipBytes;
71        return skipBytes;
72    }
73
74    @Override public int available() throws IOException {
75        return (int)raf.length() - filePosition;
76    }
77
78    @Override public boolean markSupported() {
79        return false;
80    }
81}
82