FileChannels.java
- /*
- * Licensed to the Apache Software Foundation (ASF) under one or more
- * contributor license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright ownership.
- * The ASF licenses this file to You 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.
- */
- package org.apache.commons.io.channels;
- import java.io.IOException;
- import java.nio.ByteBuffer;
- import java.nio.channels.FileChannel;
- import java.util.Objects;
- import org.apache.commons.io.IOUtils;
- /**
- * Works with {@link FileChannel}.
- *
- * @since 2.15.0
- */
- public final class FileChannels {
- /**
- * Tests if two RandomAccessFiles contents are equal.
- *
- * @param channel1 A FileChannel.
- * @param channel2 Another FileChannel.
- * @param byteBufferSize The two internal buffer capacities, in bytes.
- * @return true if the contents of both RandomAccessFiles are equal, false otherwise.
- * @throws IOException if an I/O error occurs.
- */
- public static boolean contentEquals(final FileChannel channel1, final FileChannel channel2, final int byteBufferSize) throws IOException {
- // Short-circuit test
- if (Objects.equals(channel1, channel2)) {
- return true;
- }
- // Short-circuit test
- final long size1 = size(channel1);
- final long size2 = size(channel2);
- if (size1 != size2) {
- return false;
- }
- if (size1 == 0 && size2 == 0) {
- return true;
- }
- // Dig in and do the work
- final ByteBuffer byteBuffer1 = ByteBuffer.allocateDirect(byteBufferSize);
- final ByteBuffer byteBuffer2 = ByteBuffer.allocateDirect(byteBufferSize);
- while (true) {
- final int read1 = channel1.read(byteBuffer1);
- final int read2 = channel2.read(byteBuffer2);
- byteBuffer1.clear();
- byteBuffer2.clear();
- if (read1 == IOUtils.EOF && read2 == IOUtils.EOF) {
- return byteBuffer1.equals(byteBuffer2);
- }
- if (read1 != read2) {
- return false;
- }
- if (!byteBuffer1.equals(byteBuffer2)) {
- return false;
- }
- }
- }
- private static long size(final FileChannel channel) throws IOException {
- return channel != null ? channel.size() : 0;
- }
- /**
- * Don't instantiate.
- */
- private FileChannels() {
- // no-op
- }
- }