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java.lang.Objectcom.trolltech.qt.internal.QSignalEmitterInternal
com.trolltech.qt.QSignalEmitter
com.trolltech.qt.QtJambiObject
com.trolltech.qt.core.QUuid
public class QUuid
The QUuid class stores a Universally Unique Identifier (UUID). Using Universally Unique IDentifiers (UUID) is a standard way to uniquely identify entities in a distributed computing environment. A UUID is a 16-byte (128-bit) number generated by some algorithm that is meant to guarantee that the UUID will be unique in the distributed computing environment where it is used. The acronym GUID is often used instead, Globally Unique IDentifiers, but it refers to the same thing. Actually, the GUID is one variant of UUID. Multiple variants are in use. Each UUID contains a bit field that specifies which type (variant) of UUID it is. Call variant()
to discover which type of UUID an instance of QUuid contains. It extracts the three most signifcant bits of byte 8 of the 16 bytes. In QUuid, byte 8 is QUuid::data4[0]. If you create instances of QUuid using the constructor that accepts all the numeric values as parameters, use the following table to set the three most significant bits of parameter b1, which becomes QUuid::data4[0] and contains the variant field in its three most significant bits. In the table, 'x' means don't care.
0 | x | x | NCS (Network Computing System) |
1 | 0 | x | DCE (Distributed Computing Environment) |
1 | 1 | 0 | Microsoft (GUID) |
1 | 1 | 1 | Reserved for future expansion |
variant()
returns QUuid::DCE
, the UUID also contains a version field in the four most significant bits of QUuid::data3, and you can call version()
to discover which version your QUuid contains. If you create instances of QUuid using the constructor that accepts all the numeric values as parameters, use the following table to set the four most significant bits of parameter w2, which becomes QUuid::data3 and contains the version field in its four most significant bits. 0 | 0 | 0 | 1 | Time |
0 | 0 | 1 | 0 | Embedded POSIX |
0 | 0 | 1 | 1 | Name |
0 | 1 | 0 | 0 | Random |
Most platforms provide a tool for generating new UUIDs, e.g. uuidgen and guidgen. You can also use createUuid()
. UUIDs generated by createUuid()
are of the random type. Their QUuid::Version
bits are set to QUuid::Random
, and their QUuid::Variant
bits are set to QUuid::DCE
. The rest of the UUID is composed of random numbers. Theoretically, this means there is a small chance that a UUID generated by createUuid()
will not be unique. But it is a very small chance.
UUIDs can be constructed from numeric values or from strings, or using the static createUuid()
function. They can be converted to a string with toString()
. UUIDs have a variant()
and a version()
, and null UUIDs return true from isNull()
.
Nested Class Summary | |
---|---|
static class |
QUuid.Variant
This enum defines the values used in the variant field of the UUID. |
static class |
QUuid.Version
This enum defines the values used in the version field of the UUID. |
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter |
---|
QSignalEmitter.AbstractSignal, QSignalEmitter.Signal0, QSignalEmitter.Signal1, QSignalEmitter.Signal2, QSignalEmitter.Signal3, QSignalEmitter.Signal4, QSignalEmitter.Signal5, QSignalEmitter.Signal6, QSignalEmitter.Signal7, QSignalEmitter.Signal8, QSignalEmitter.Signal9 |
Nested classes/interfaces inherited from class com.trolltech.qt.internal.QSignalEmitterInternal |
---|
com.trolltech.qt.internal.QSignalEmitterInternal.AbstractSignalInternal |
Field Summary |
---|
Fields inherited from class com.trolltech.qt.internal.QSignalEmitterInternal |
---|
currentSender |
Constructor Summary | |
---|---|
QUuid()
Creates the null UUID. |
|
QUuid(int l,
char w1,
char w2,
byte b1,
byte b2,
byte b3,
byte b4,
byte b5,
byte b6,
byte b7,
byte b8)
Creates a UUID with the value specified by the parameters, l, w1, w2, b1, b2, b3, b4, b5, b6, b7, b8. |
|
QUuid(java.lang.String arg__1)
Creates a QUuid object from the string text, which must be formatted as five hex fields separated by '-', e. |
Method Summary | |
---|---|
QUuid |
clone()
This method is reimplemented for internal reasons |
static QUuid |
createUuid()
On any platform other than Windows, this function returns a new UUID with variant QUuid::DCE and version QUuid::Random . |
int |
data1()
Returns the data of this QUuid. |
char |
data2()
Returns the data of this QUuid. |
char |
data3()
Returns the data of this QUuid. |
byte[] |
data4()
|
boolean |
isNull()
Returns true if this is the null UUID {00000000-0000-0000-0000-000000000000}; otherwise returns false. |
void |
readFrom(QDataStream arg__1)
|
void |
setData1(int data1)
Sets the data of this QUuid to data1. |
void |
setData2(char data2)
Sets the data of this QUuid to data2. |
void |
setData3(char data3)
Sets the data of this QUuid to data3. |
void |
setData4(byte[] data4)
|
java.lang.String |
toString()
|
QUuid.Variant |
variant()
Returns the value in the variant field of the UUID. |
QUuid.Version |
version()
Returns the version field of the UUID, if the UUID's variant field is QUuid::DCE . |
void |
writeTo(QDataStream arg__1)
|
Methods inherited from class com.trolltech.qt.QtJambiObject |
---|
dispose, disposed, equals, finalize, reassignNativeResources, tr, tr, tr |
Methods inherited from class com.trolltech.qt.QSignalEmitter |
---|
blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread |
Methods inherited from class com.trolltech.qt.internal.QSignalEmitterInternal |
---|
__qt_signalInitialization |
Methods inherited from class java.lang.Object |
---|
getClass, hashCode, notify, notifyAll, wait, wait, wait |
Methods inherited from interface java.lang.Comparable |
---|
compareTo |
Methods inherited from interface com.trolltech.qt.QtJambiInterface |
---|
disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership |
Constructor Detail |
---|
public QUuid()
toString()
will output the null UUID as "{00000000-0000-0000-0000-000000000000}".
public QUuid(java.lang.String arg__1)
toString()
for an explanation of how the five hex fields map to the public data members in QUuid. toString()
, and QUuid().
public QUuid(int l, char w1, char w2, byte b1, byte b2, byte b3, byte b4, byte b5, byte b6, byte b7, byte b8)
Example:
Missing snippet: doc/src/snippets/code/src_corelib_plugin.quuid.cpp.
Method Detail |
---|
public final boolean isNull()
public final void writeTo(QDataStream arg__1)
public final void readFrom(QDataStream arg__1)
public final java.lang.String toString()
toString
in class java.lang.Object
public final QUuid.Variant variant()
QUuid::DCE
, call version()
to see which layout it uses. The null UUID is considered to be of an unknown variant. version()
.
public final QUuid.Version version()
QUuid::DCE
. Otherwise it returns QUuid::VerUnknown
. variant()
.
public static QUuid createUuid()
QUuid::DCE
and version QUuid::Random
. The random numbers used to construct the UUID are obtained from the local pseudo-random generator, which is usually not a cryptographic quality random number generator. Therefore, a UUID generated by this function can't be guaranteed to be unique. On a Windows platform, a GUID is generated, which almost certainly will be unique, on this or any other system, networked or not.
variant()
, and version()
.
public final void setData1(int data1)
public final int data1()
public final void setData2(char data2)
public final char data2()
public final void setData3(char data3)
public final char data3()
public final void setData4(byte[] data4)
public final byte[] data4()
public QUuid clone()
clone
in class java.lang.Object
|
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