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137 lines (129 loc) · 4.49 KB
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/*
* Copyright (c) 1996, 2014, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package java.util.zip;
import java.nio.ByteBuffer;
/**
* An interface representing a data checksum.
*
* @author David Connelly
* @since 1.1
*/
public interface Checksum {
/**
* Updates the current checksum with the specified byte.
*
* @param b the byte to update the checksum with
*/
public void update(int b);
/**
* Updates the current checksum with the specified array of bytes.
*
* @implSpec This default implementation is equal to calling
* {@code update(b, 0, b.length)}.
*
* @param b the array of bytes to update the checksum with
*
* @throws NullPointerException
* if {@code b} is {@code null}
*
* @since 9
*/
default public void update(byte[] b) {
update(b, 0, b.length);
}
/**
* Updates the current checksum with the specified array of bytes.
*
* @param b the byte array to update the checksum with
* @param off the start offset of the data
* @param len the number of bytes to use for the update
*/
public void update(byte[] b, int off, int len);
/**
* Updates the current checksum with the bytes from the specified buffer.
*
* The checksum is updated with the remaining bytes in the buffer, starting
* at the buffer's position. Upon return, the buffer's position will be
* updated to its limit; its limit will not have been changed.
*
* @apiNote For best performance with DirectByteBuffer and other ByteBuffer
* implementations without a backing array implementers of this interface
* should override this method.
*
* @implSpec The default implementation has the following behavior.<br>
* For ByteBuffers backed by an accessible byte array.
* <pre>{@code
* update(buffer.array(),
* buffer.position() + buffer.arrayOffset(),
* buffer.remaining());
* }</pre>
* For ByteBuffers not backed by an accessible byte array.
* <pre>{@code
* byte[] b = new byte[Math.min(buffer.remaining(), 4096)];
* while (buffer.hasRemaining()) {
* int length = Math.min(buffer.remaining(), b.length);
* buffer.get(b, 0, length);
* update(b, 0, length);
* }
* }</pre>
*
* @param buffer the ByteBuffer to update the checksum with
*
* @throws NullPointerException
* if {@code buffer} is {@code null}
*
* @since 9
*/
default public void update(ByteBuffer buffer) {
int pos = buffer.position();
int limit = buffer.limit();
assert (pos <= limit);
int rem = limit - pos;
if (rem <= 0) {
return;
}
if (buffer.hasArray()) {
update(buffer.array(), pos + buffer.arrayOffset(), rem);
} else {
byte[] b = new byte[Math.min(buffer.remaining(), 4096)];
while (buffer.hasRemaining()) {
int length = Math.min(buffer.remaining(), b.length);
buffer.get(b, 0, length);
update(b, 0, length);
}
}
buffer.position(limit);
}
/**
* Returns the current checksum value.
*
* @return the current checksum value
*/
public long getValue();
/**
* Resets the checksum to its initial value.
*/
public void reset();
}