CountedDataInputStream.java revision e8d1bf7a439450b9979701909164a6baffbe8bae 
1/*
2 * Copyright (C) 2012 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.android.gallery3d.exif;
18
19import java.io.EOFException;
20import java.io.FilterInputStream;
21import java.io.IOException;
22import java.io.InputStream;
23import java.nio.ByteBuffer;
24import java.nio.ByteOrder;
25import java.nio.charset.Charset;
26
27class CountedDataInputStream extends FilterInputStream {
28
29    private int mCount = 0;
30
31    // allocate a byte buffer for a long value;
32    private final byte mByteArray[] = new byte[8];
33    private final ByteBuffer mByteBuffer = ByteBuffer.wrap(mByteArray);
34
35    protected CountedDataInputStream(InputStream in) {
36        super(in);
37    }
38
39    public int getReadByteCount() {
40        return mCount;
41    }
42
43    @Override
44    public int read(byte[] b) throws IOException {
45        int r = in.read(b);
46        mCount += (r >= 0) ? r : 0;
47        return r;
48    }
49
50    @Override
51    public int read(byte[] b, int off, int len) throws IOException {
52        int r = in.read(b, off, len);
53        mCount += (r >= 0) ? r : 0;
54        return r;
55    }
56
57    @Override
58    public int read() throws IOException {
59        int r = in.read();
60        mCount += (r >= 0) ? 1 : 0;
61        return r;
62    }
63
64    @Override
65    public long skip(long length) throws IOException {
66        long skip = in.skip(length);
67        mCount += skip;
68        return skip;
69    }
70
71    public void skipOrThrow(long length) throws IOException {
72        if (skip(length) != length) throw new EOFException();
73    }
74
75    public void skipTo(long target) throws IOException {
76        long cur = mCount;
77        long diff = target - cur;
78        assert(diff >= 0);
79        skipOrThrow(diff);
80    }
81
82    public void readOrThrow(byte[] b, int off, int len) throws IOException {
83        int r = read(b, off, len);
84        if (r != len) throw new EOFException();
85    }
86
87    public void readOrThrow(byte[] b) throws IOException {
88        readOrThrow(b, 0, b.length);
89    }
90
91    public void setByteOrder(ByteOrder order) {
92        mByteBuffer.order(order);
93    }
94
95    public ByteOrder getByteOrder() {
96        return mByteBuffer.order();
97    }
98
99    public short readShort() throws IOException {
100        readOrThrow(mByteArray, 0 ,2);
101        mByteBuffer.rewind();
102        return mByteBuffer.getShort();
103    }
104
105    public int readUnsignedShort() throws IOException {
106        return readShort() & 0xffff;
107    }
108
109    public int readInt() throws IOException {
110        readOrThrow(mByteArray, 0 , 4);
111        mByteBuffer.rewind();
112        return mByteBuffer.getInt();
113    }
114
115    public long readUnsignedInt() throws IOException {
116        return readInt() & 0xffffffffL;
117    }
118
119    public long readLong() throws IOException {
120        readOrThrow(mByteArray, 0 , 8);
121        mByteBuffer.rewind();
122        return mByteBuffer.getLong();
123    }
124
125    public String readString(int n) throws IOException {
126        byte buf[] = new byte[n];
127        readOrThrow(buf);
128        return new String(buf, "UTF8");
129    }
130
131    public String readString(int n, Charset charset) throws IOException {
132        byte buf[] = new byte[n];
133        readOrThrow(buf);
134        return new String(buf, charset);
135    }
136}