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package java.util.zip;
import java.nio.ByteBuffer;
An interface representing a data checksum.
Author: David Connelly Since: 1.1
/**
* An interface representing a data checksum.
*
* @author David Connelly
* @since 1.1
*/
public interface Checksum {
Updates the current checksum with the specified byte.
Params: - b – the byte to update the checksum with
/**
* 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.
Params: - b – the array of bytes to update the checksum with
Throws: - NullPointerException – if
b is null
Implementation Requirements: This default implementation is equal to calling update(b, 0, b.length). Since: 9
/**
* 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.
Params: - b – the byte array to update the checksum with
- off – the start offset of the data
- len – the number of bytes to use for the update
/**
* 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.
Params: - buffer – the ByteBuffer to update the checksum with
Throws: - NullPointerException – if
buffer is null
API Note: For best performance with DirectByteBuffer and other ByteBuffer
implementations without a backing array implementers of this interface
should override this method. Implementation Requirements: The default implementation has the following behavior.
For ByteBuffers backed by an accessible byte array.
update(buffer.array(),
buffer.position() + buffer.arrayOffset(),
buffer.remaining());
For ByteBuffers not backed by an accessible byte array.
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);
}
Since: 9
/**
* 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.
Returns: the current checksum value
/**
* Returns the current checksum value.
*
* @return the current checksum value
*/
public long getValue();
Resets the checksum to its initial value.
/**
* Resets the checksum to its initial value.
*/
public void reset();
}