org.opencms.util
Class CmsUUID

java.lang.Object
  org.opencms.util.CmsUUID

All Implemented Interfaces:

Externalizable, Serializable, Cloneable, Comparable

public final class CmsUUID
extends Object
implements Serializable, Cloneable, Comparable, Externalizable

Generates a UUID using spatial and temporal uniqueness.

Spatial uniqueness is derived from ethernet address (MAC, 802.1); temporal from system clock.

For more information about the algorithm used, please see draft-leach-uuids-guids-01.txt.

Because Java is unable to read the MAC address of the machine (without using JNI), the MAC address has to be provided first by using the static init(String) method.

This class is just a facade wrapper for the "real" UUID implementation.

Since:

6.0.0

Version:

$Revision: 1.21 $

Author:

Alexander Kandzior

See Also:

Serialized Form

Constructor Summary

CmsUUID()
Creates a new UUID.

CmsUUID(byte[] data)
Create a UUID based on a binary data array.

CmsUUID(String uuid)
Create a UUID based on a String.

Method Summary

static void	checkId(CmsUUID id, boolean canBeNull) Check that the given id is not the null id.
Object	clone() Creates a clone of this CmsUUID.
int	compareTo(Object obj)
boolean	equals(Object obj)
static CmsUUID	getConstantUUID(String name) Returns a constant (name based) UUID, based on the given name in the OpenCms name space.
static String	getDummyEthernetAddress() Returns a String representing a dummy (random based) ethernet address.
static CmsUUID	getNullUUID() Returns a null UUID, use this null UUID to check if a UUID has been initilized or not.
static CmsUUID	getOpenCmsUUID() Returns a constant (name based) UUID for OpenCms, based on "www.opencms.org" in the dns name space.
int	hashCode() Optimized hashCode implementation for UUID's.
static void	init(String ethernetAddress) Initialize the UUID generator with the ethernet address of the server machine.
boolean	isNullUUID() Returns true if this UUID is equal to the null UUID.
static boolean	isValidUUID(String uuid) Returns true if the given UUID is valid.
void	readExternal(ObjectInput in)
byte[]	toByteArray() Returns the UUID as a 16-byte byte array.
String	toString()
void	writeExternal(ObjectOutput out)

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

CmsUUID

public CmsUUID()

Creates a new UUID.

Please note that the static init() method has to be called first to initialize the enternet address of the machine.

CmsUUID

public CmsUUID(byte[] data)

Create a UUID based on a binary data array.

Parameters:

data - a binary data array representing a UUID

CmsUUID

public CmsUUID(String uuid)
        throws NumberFormatException

Create a UUID based on a String.

Parameters:

uuid - a String representing a UUID

Throws:

NumberFormatException - in case uuid is not a valid UUID

Method Detail

checkId

public static void checkId(CmsUUID id,
                           boolean canBeNull)

Check that the given id is not the null id.

Parameters:

id - the id to check

canBeNull - only if flag is set, null is accepted

See Also:

isNullUUID()

getConstantUUID

public static CmsUUID getConstantUUID(String name)

Returns a constant (name based) UUID, based on the given name in the OpenCms name space.

Parameters:

name - the name to derive the uuid from

Returns:

name based UUID of the given name

getDummyEthernetAddress

public static String getDummyEthernetAddress()

Returns a String representing a dummy (random based) ethernet address.

Returns:

a String representing a dummy (random based) ethernet address

getNullUUID

public static CmsUUID getNullUUID()

Returns a null UUID, use this null UUID to check if a UUID has been initilized or not.

Returns:

a null UUID

getOpenCmsUUID

public static CmsUUID getOpenCmsUUID()

Returns a constant (name based) UUID for OpenCms, based on "www.opencms.org" in the dns name space.

Returns:

name based UUID of OpenCms

init

public static void init(String ethernetAddress)
                 throws CmsInitException

Initialize the UUID generator with the ethernet address of the server machine.

The ethernetAddress parameter must represent a 'standard' ethernet MAC address string (e.g. '00:C0:F0:3D:5B:7C').

Parameters:

ethernetAddress - the ethernet address of the server machine

Throws:

CmsInitException - in case the ethernetAddress String is not a valid ethernet address

isValidUUID

public static boolean isValidUUID(String uuid)

Returns true if the given UUID is valid.

Parameters:

uuid - the UUID to check

Returns:

true if the given UUID is valid

clone

public Object clone()

Creates a clone of this CmsUUID.

Overrides:

clone in class Object

Returns:

a clone of this CmsUUID

compareTo

public int compareTo(Object obj)

Specified by:

compareTo in interface Comparable

See Also:

Comparable.compareTo(java.lang.Object)

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

See Also:

Object.equals(java.lang.Object)

hashCode

public int hashCode()

Optimized hashCode implementation for UUID's.

Overrides:

hashCode in class Object

See Also:

Object.hashCode()

isNullUUID

public boolean isNullUUID()

Returns true if this UUID is equal to the null UUID.

Returns:

true if this UUID is equal to the null UUID

readExternal

public void readExternal(ObjectInput in)
                  throws IOException,
                         ClassNotFoundException

Specified by:

readExternal in interface Externalizable

Throws:

IOException

ClassNotFoundException

See Also:

Externalizable.readExternal(java.io.ObjectInput)

toByteArray

public byte[] toByteArray()

Returns the UUID as a 16-byte byte array.

Returns:

16-byte byte array that contains the UUID's bytes in the network byte order

toString

public String toString()

Overrides:

toString in class Object

See Also:

Object.toString()

writeExternal

public void writeExternal(ObjectOutput out)
                   throws IOException

Specified by:

writeExternal in interface Externalizable

Throws:

IOException

See Also:

Externalizable.writeExternal(java.io.ObjectOutput)