138 lines
4.5 KiB
Java
138 lines
4.5 KiB
Java
/*
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* Copyright (c) 1996, 2014, 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. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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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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package java.util.zip;
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import java.nio.ByteBuffer;
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/**
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* An interface representing a data checksum.
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*
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* @author David Connelly
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* @since 1.1
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*/
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public interface Checksum {
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/**
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* Updates the current checksum with the specified byte.
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*
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* @param b the byte to update the checksum with
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*/
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public void update(int b);
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/**
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* Updates the current checksum with the specified array of bytes.
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*
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* @implSpec This default implementation is equal to calling
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* {@code update(b, 0, b.length)}.
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*
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* @param b the array of bytes to update the checksum with
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*
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* @throws NullPointerException
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* if {@code b} is {@code null}
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*
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* @since 9
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*/
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default public void update(byte[] b) {
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update(b, 0, b.length);
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}
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/**
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* Updates the current checksum with the specified array of bytes.
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*
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* @param b the byte array to update the checksum with
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* @param off the start offset of the data
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* @param len the number of bytes to use for the update
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*/
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public void update(byte[] b, int off, int len);
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/**
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* Updates the current checksum with the bytes from the specified buffer.
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*
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* The checksum is updated with the remaining bytes in the buffer, starting
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* at the buffer's position. Upon return, the buffer's position will be
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* updated to its limit; its limit will not have been changed.
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*
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* @apiNote For best performance with DirectByteBuffer and other ByteBuffer
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* implementations without a backing array implementers of this interface
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* should override this method.
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*
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* @implSpec The default implementation has the following behavior.<br>
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* For ByteBuffers backed by an accessible byte array.
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* <pre>{@code
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* update(buffer.array(),
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* buffer.position() + buffer.arrayOffset(),
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* buffer.remaining());
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* }</pre>
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* For ByteBuffers not backed by an accessible byte array.
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* <pre>{@code
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* byte[] b = new byte[Math.min(buffer.remaining(), 4096)];
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* while (buffer.hasRemaining()) {
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* int length = Math.min(buffer.remaining(), b.length);
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* buffer.get(b, 0, length);
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* update(b, 0, length);
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* }
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* }</pre>
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*
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* @param buffer the ByteBuffer to update the checksum with
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*
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* @throws NullPointerException
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* if {@code buffer} is {@code null}
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*
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* @since 9
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*/
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default public void update(ByteBuffer buffer) {
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int pos = buffer.position();
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int limit = buffer.limit();
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assert (pos <= limit);
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int rem = limit - pos;
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if (rem <= 0) {
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return;
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}
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if (buffer.hasArray()) {
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update(buffer.array(), pos + buffer.arrayOffset(), rem);
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} else {
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byte[] b = new byte[Math.min(buffer.remaining(), 4096)];
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while (buffer.hasRemaining()) {
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int length = Math.min(buffer.remaining(), b.length);
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buffer.get(b, 0, length);
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update(b, 0, length);
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}
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}
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buffer.position(limit);
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}
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/**
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* Returns the current checksum value.
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*
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* @return the current checksum value
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*/
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public long getValue();
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/**
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* Resets the checksum to its initial value.
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*/
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public void reset();
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}
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