119 lines
4.3 KiB
Java
119 lines
4.3 KiB
Java
/*
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* Copyright (c) 2021, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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/* @test
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* @bug 8140241
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* @summary Test transferring to and from same file channel
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*/
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import java.io.BufferedOutputStream;
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import java.io.File;
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import java.io.FileOutputStream;
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import java.io.OutputStream;
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import java.io.RandomAccessFile;
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import java.io.IOException;
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import java.nio.channels.FileChannel;
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import java.util.Random;
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public class TransferOverlappedFileChannel {
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public static void main(String[] args) throws Exception {
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File file = File.createTempFile("readingin", null);
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file.deleteOnExit();
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generateBigFile(file);
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RandomAccessFile raf = new RandomAccessFile(file, "rw");
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try (FileChannel channel = raf.getChannel()) {
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transferToNoOverlap(file, channel);
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transferToOverlap(file, channel);
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transferFromNoOverlap(file, channel);
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transferFromOverlap(file, channel);
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} finally {
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file.delete();
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}
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}
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private static void transferToNoOverlap(File file, FileChannel channel)
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throws IOException {
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final long length = file.length();
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// position at three quarters
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channel.position(length*3/4);
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// copy last quarter to third quarter
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// (copied and overwritten regions do NOT overlap)
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// So: 1 2 3 4 -> 1 2 4 4
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channel.transferTo(length / 2, length / 4, channel);
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System.out.println("transferToNoOverlap: OK");
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}
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private static void transferToOverlap(File file, FileChannel channel)
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throws IOException {
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final long length = file.length();
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// position at half
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channel.position(length/2);
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// copy last half to second quarter
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// (copied and overwritten regions DO overlap)
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// So: 1 2 3 4 -> 1 3 4 4
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channel.transferTo(length / 4, length / 2, channel);
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System.out.println("transferToOverlap: OK");
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}
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private static void transferFromNoOverlap(File file, FileChannel channel)
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throws IOException {
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final long length = file.length();
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// position at three quarters
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channel.position(length*3/4);
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// copy last quarter to third quarter
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// (copied and overwritten regions do NOT overlap)
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// So: 1 2 3 4 -> 1 2 4 4
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channel.transferFrom(channel, length / 2, length / 4);
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System.out.println("transferFromNoOverlap: OK");
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}
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private static void transferFromOverlap(File file, FileChannel channel)
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throws IOException {
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final long length = file.length();
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// position at half
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channel.position(length/2);
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// copy last half to second quarter
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// (copied and overwritten regions DO overlap)
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// So: 1 2 3 4 -> 1 3 4 4
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channel.transferFrom(channel, length / 4, length / 2);
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System.out.println("transferFromOverlap: OK");
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}
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private static void generateBigFile(File file) throws Exception {
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try (OutputStream out = new BufferedOutputStream(
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new FileOutputStream(file))) {
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byte[] randomBytes = new byte[1024];
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Random rand = new Random(0);
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rand.nextBytes(randomBytes);
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for (int i = 0; i < 1024; i++) {
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out.write(randomBytes);
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}
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out.flush();
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}
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}
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}
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