Package edu.harvard.hul.ois.jhove

Class Checksummer

java.lang.Object

edu.harvard.hul.ois.jhove.Checksummer

All Implemented Interfaces:

Checksum

public class Checksummer
extends Object
implements Checksum

The Checksummer class encapsulates the calculation of the CRC32, MD5, SHA-1 and SHA-256 checksums.

Field Summary

Fields

Modifier and Type	Field	Description
protected long	_nByte	Byte count.

Constructor Summary

Constructors

Constructor	Description
Checksummer()	Creates a Checksummer, with instances of each of CRC32, MD5, SHA-1 and SHA-256 MessageDigest.

Method Summary

Modifier and Type	Method	Description
String	getCRC32()	Returns the value of the CRC32 as a hex string.
String	getMD5()	Returns the value of the MD5 digest as a hex string.
String	getSHA1()	Returns the value of the SHA-1 digest as a hex string.
String	getSHA256()	Returns the value of the SHA-256 digest as a hex string.
long	getValue()	getValue is required by the Checksum interface, but we can return only one of the three values.
void	reset()	Resets all checksums and the byte count to their initial values.
void	update(byte b)	Updates the checksum with the argument.
void	update(byte[] b)	Updates the checksum with the argument.
void	update(byte[] b, int off, int len)	Updates the checksum with the argument.
void	update(int b)	Updates the checksum with the argument.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.util.zip.Checksum

update

Field Detail

_nByte

protected long _nByte

Byte count.

Constructor Detail

Checksummer

public Checksummer()

Creates a Checksummer, with instances of each of CRC32, MD5, SHA-1 and SHA-256 MessageDigest. If one or both of the MessageDigests aren't supported on the current platform, they are left as null.

See Also:

CRC32, MessageDigest

Method Detail

reset

public void reset()

Resets all checksums and the byte count to their initial values.

Specified by:

reset in interface Checksum

getValue

public long getValue()

getValue is required by the Checksum interface, but we can return only one of the three values. We return the CRC32 value, since that's the one which is guaranteed to be available.

Specified by:

getValue in interface Checksum

update

public void update(byte b)

Updates the checksum with the argument. Called when a signed byte is available.

update

public void update(int b)

Updates the checksum with the argument. Called when an unsigned byte is available.

Specified by:

update in interface Checksum

update

public void update(byte[] b)

Updates the checksum with the argument. Called when a byte array is available.

Specified by:

update in interface Checksum

update

public void update(byte[] b,
                   int off,
                   int len)

Updates the checksum with the argument. Called when a byte array is available.

Specified by:

update in interface Checksum

getCRC32

public String getCRC32()

Returns the value of the CRC32 as a hex string.

getMD5

public String getMD5()

Returns the value of the MD5 digest as a hex string. Returns null if the digest is not available.

getSHA1

public String getSHA1()

Returns the value of the SHA-1 digest as a hex string. Returns null if the digest is not available.

getSHA256

public String getSHA256()

Returns the value of the SHA-256 digest as a hex string. Returns null if the digest is not available.