com.phloc.commons.messagedigest

Class MessageDigestGenerator

java.lang.Object

com.phloc.commons.messagedigest.AbstractMessageDigestGenerator

com.phloc.commons.messagedigest.MessageDigestGenerator

All Implemented Interfaces:

IMessageDigestGenerator

public final class MessageDigestGenerator
extends AbstractMessageDigestGenerator

Base class for creating a cryptographic hash value. Don't mix it up with the HashCodeGenerator which is used to generate hash values for Java objects.

Author:

Philip Helger

Field Summary

Fields inherited from interface com.phloc.commons.messagedigest.IMessageDigestGenerator

DEFAULT_ALGORITHM

Constructor Summary

Constructors

Constructor and Description
MessageDigestGenerator() Create a default hash generator with the default algorithm.
MessageDigestGenerator(EMessageDigestAlgorithm... aAlgorithms) Create a hash generator with a set of possible algorithms to use.

Method Summary

Methods

Modifier and Type	Method and Description
String	getAlgorithmName()
byte[]	getDigest() Finish calculation of the hash value and return the digest.
byte[]	getDigest(int nLength) Get only a part of the digest, namely the first number of bytes.
int	getDigestLength()
void	reset() Reset the current hash so that generation can start from scratch again.
String	toString()
MessageDigestGenerator	update(byte aValue) Update the hash with the given byte.
MessageDigestGenerator	update(byte[] aValue, int nOffset, int nLength) Update the hash with a slice of the given byte array.

Methods inherited from class com.phloc.commons.messagedigest.AbstractMessageDigestGenerator

getDigestHexString, getDigestLong, update, update, update

Methods inherited from class java.lang.Object

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

Constructor Detail

MessageDigestGenerator

public MessageDigestGenerator()

Create a default hash generator with the default algorithm.

MessageDigestGenerator

public MessageDigestGenerator(@Nonnull@Nonempty
                      EMessageDigestAlgorithm... aAlgorithms)

Create a hash generator with a set of possible algorithms to use.

Parameters:

aAlgorithms - The parameters to test. May not be null.

Throws:

NullPointerException - If the array of algorithms is null or if one element of the array is null.

IllegalArgumentException - If no algorithm was passed or if no applicable algorithm was used.

Method Detail

getAlgorithmName

@Nonnull
public String getAlgorithmName()

Returns:

The name of the hashing algorithm used.

getDigestLength

@Nonnegative
public int getDigestLength()

Returns:

Returns the length of the digest in bytes, or 0 if this operation is not supported by the provider.

update

@Nonnull
public MessageDigestGenerator update(byte aValue)

Description copied from interface: IMessageDigestGenerator

Update the hash with the given byte. After calling IMessageDigestGenerator.getDigest() once, no further update is possible.

Parameters:

aValue - The byte value to update the hash

Returns:

this

update

@Nonnull
public MessageDigestGenerator update(@Nonnull
                                    byte[] aValue,
                                    @Nonnegative
                                    int nOffset,
                                    @Nonnegative
                                    int nLength)

Description copied from interface: IMessageDigestGenerator

Update the hash with a slice of the given byte array. After calling IMessageDigestGenerator.getDigest() once, no further update is possible.

Parameters:

aValue - The byte array to update the hash. May not be null.

nOffset - The offset within the byte array from which the value should be taken. May not be < 0.

nLength - The number of bytes to use, starting from the passed offset. May not be < 0.

Returns:

this

reset

public void reset()

Description copied from interface: IMessageDigestGenerator

Reset the current hash so that generation can start from scratch again.

getDigest

@Nonnull
@ReturnsMutableCopy
public byte[] getDigest()

Description copied from interface: IMessageDigestGenerator

Finish calculation of the hash value and return the digest. Afterwards no update is possible before IMessageDigestGenerator.reset() is called.

Returns:

A copy of the array with the message digest.

getDigest

@Nonnull
@ReturnsMutableCopy
public byte[] getDigest(@Nonnegative
                                          int nLength)

Description copied from interface: IMessageDigestGenerator

Get only a part of the digest, namely the first number of bytes. Calls IMessageDigestGenerator.getDigest() internally so no further update is possible after this method is called.

Parameters:

nLength - The number of bytes to be retrieved. Must be > 0.

Returns:

A copy of the first n bytes of the message digest array.

toString

public String toString()

Overrides:

toString in class Object