1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.commons.io.channels;
19
20 import java.io.IOException;
21 import java.nio.ByteBuffer;
22 import java.nio.channels.FileChannel;
23 import java.util.Objects;
24
25 import org.apache.commons.io.IOUtils;
26
27 /**
28 * Works with {@link FileChannel}.
29 *
30 * @since 2.15.0
31 */
32 public final class FileChannels {
33
34 /**
35 * Tests if two RandomAccessFiles contents are equal.
36 *
37 * @param channel1 A FileChannel.
38 * @param channel2 Another FileChannel.
39 * @param byteBufferSize The two internal buffer capacities, in bytes.
40 * @return true if the contents of both RandomAccessFiles are equal, false otherwise.
41 * @throws IOException if an I/O error occurs.
42 */
43 public static boolean contentEquals(final FileChannel channel1, final FileChannel channel2, final int byteBufferSize) throws IOException {
44 // Short-circuit test
45 if (Objects.equals(channel1, channel2)) {
46 return true;
47 }
48 // Short-circuit test
49 final long size1 = size(channel1);
50 final long size2 = size(channel2);
51 if (size1 != size2) {
52 return false;
53 }
54 if (size1 == 0 && size2 == 0) {
55 return true;
56 }
57 // Dig in and do the work
58 final ByteBuffer byteBuffer1 = ByteBuffer.allocateDirect(byteBufferSize);
59 final ByteBuffer byteBuffer2 = ByteBuffer.allocateDirect(byteBufferSize);
60 while (true) {
61 final int read1 = channel1.read(byteBuffer1);
62 final int read2 = channel2.read(byteBuffer2);
63 byteBuffer1.clear();
64 byteBuffer2.clear();
65 if (read1 == IOUtils.EOF && read2 == IOUtils.EOF) {
66 return byteBuffer1.equals(byteBuffer2);
67 }
68 if (read1 != read2) {
69 return false;
70 }
71 if (!byteBuffer1.equals(byteBuffer2)) {
72 return false;
73 }
74 }
75 }
76
77 private static long size(final FileChannel channel) throws IOException {
78 return channel != null ? channel.size() : 0;
79 }
80
81 /**
82 * Don't instantiate.
83 */
84 private FileChannels() {
85 // no-op
86 }
87 }