com.github.f4b6a3.uuid.factory.abst

Class AbstractNameBasedUuidCreator

java.lang.Object

com.github.f4b6a3.uuid.factory.abst.AbstractUuidCreator

com.github.f4b6a3.uuid.factory.abst.AbstractNameBasedUuidCreator

Direct Known Subclasses:

NameBasedMd5UuidCreator, NameBasedSha1UuidCreator, NameBasedSha256UuidCreator

public abstract class AbstractNameBasedUuidCreator
extends AbstractUuidCreator

Factory that creates name-based UUIDs versions 3 and 5.

Field Summary

Fields

Modifier and Type	Field and Description
protected static String	MESSAGE_DIGEST_MD5
protected static String	MESSAGE_DIGEST_SHA1
protected static String	MESSAGE_DIGEST_SHA256

Fields inherited from class com.github.f4b6a3.uuid.factory.abst.AbstractUuidCreator

NIL_UUID, RFC4122_VARIANT_BITS, RFC4122_VERSION_BITS, version

Constructor Summary

Constructors

Constructor and Description
AbstractNameBasedUuidCreator(UuidVersion version, String messageDigest) This constructor receives the name of a message digest.

Method Summary

Modifier and Type	Method and Description
UUID	create(String name) Returns a name-based UUID without namespace.
UUID	create(String namespace, String name) Returns a name-based UUID with a namespace and a name.
UUID	create(UUID namespace, String name) Returns a name-based UUID with a namespace and a name. ### RFC-4122 - 4.3.
<T extends AbstractNameBasedUuidCreator> T	withNamespace(String namespace) Sets a fixed namespace with in a fluent way.
<T extends AbstractNameBasedUuidCreator> T	withNamespace(UUID namespace) Sets a fixed namespace with in a fluent way.

Methods inherited from class com.github.f4b6a3.uuid.factory.abst.AbstractUuidCreator

getVariantBits, getVersion, getVersionBits, setVariantBits, setVersionBits, valid

Methods inherited from class java.lang.Object

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

Field Detail

MESSAGE_DIGEST_MD5

protected static final String MESSAGE_DIGEST_MD5

See Also:

Constant Field Values

MESSAGE_DIGEST_SHA1

protected static final String MESSAGE_DIGEST_SHA1

See Also:

Constant Field Values

MESSAGE_DIGEST_SHA256

protected static final String MESSAGE_DIGEST_SHA256

See Also:

Constant Field Values

Constructor Detail

AbstractNameBasedUuidCreator

public AbstractNameBasedUuidCreator(UuidVersion version,
                                    String messageDigest)

This constructor receives the name of a message digest. In this implementation it's possible to use ANY message digest that Java supports, but only MD5 and SHA-1 are used by the the RFC-4122. Someone can implement a non-standard name-based factory that uses a better message digest, by extending this abstract class.

Parameters:

version - the version number

messageDigest - a message digest

Method Detail

withNamespace

public <T extends AbstractNameBasedUuidCreator> T withNamespace(UUID namespace)

Sets a fixed namespace with in a fluent way.

Type Parameters:

T - the type parameter

Parameters:

namespace - a namespace UUID

Returns:

AbstractNameBasedUuidCreator

withNamespace

public <T extends AbstractNameBasedUuidCreator> T withNamespace(String namespace)

Sets a fixed namespace with in a fluent way. The namespace string is converted to namespace UUID.

Type Parameters:

T - the type parameter

Parameters:

namespace - a namespace string

Returns:

AbstractNameBasedUuidCreator

create

public UUID create(String name)

Returns a name-based UUID without namespace. create(UUID, String)

Parameters:

name - a name string

Returns:

a name-based UUID

create

public UUID create(String namespace,
                   String name)

Returns a name-based UUID with a namespace and a name. The namespace string is converted to namespace UUID. create(UUID, String)

Parameters:

namespace - a namespace string

name - a name string

Returns:

a name-based UUID

create

public UUID create(UUID namespace,
                   String name)

Returns a name-based UUID with a namespace and a name. ### RFC-4122 - 4.3. Algorithm for Creating a Name-Based UUID (1) Allocate a UUID to use as a "name space ID" for all UUIDs generated from names in that name space; see Appendix C for some pre-defined values. (2) Choose either MD5 [4] or SHA-1 [8] as the hash algorithm; If backward compatibility is not an issue, SHA-1 is preferred. (3) Convert the name to a canonical sequence of octets (as defined by the standards or conventions of its name space); put the name space ID in network byte order. (4) Compute the hash of the name space ID concatenated with the name. (5) Set octets zero through 3 of the time_low field to octets zero through 3 of the hash. (6) Set octets zero and one of the time_mid field to octets 4 and 5 of the hash. (7) Set octets zero and one of the time_hi_and_version field to octets 6 and 7 of the hash. (8) Set the four most significant bits (bits 12 through 15) of the time_hi_and_version field to the appropriate 4-bit version number from Section 4.1.3. (9) Set the clock_seq_hi_and_reserved field to octet 8 of the hash. (10) Set the two most significant bits (bits 6 and 7) of the clock_seq_hi_and_reserved to zero and one, respectively. (11) Set the clock_seq_low field to octet 9 of the hash. (12) Set octets zero through five of the node field to octets 10 through 15 of the hash. (13) Convert the resulting UUID to local byte order.

Parameters:

namespace - a namespace UUID

name - a name string

Returns:

a name-based UUID