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HHH-5268 Add documentation for uuid and uuid2 identifier generators 

git-svn-id: https://svn.jboss.org/repos/hibernate/core/trunk@19648 1b8cb986-b30d-0410-93ca-fae66ebed9b2
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Emmanuel Bernard 2010-06-01 23:23:40 +00:00
parent 94f5659503
commit 3dd364c716
1 changed files with 71 additions and 4 deletions
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75
documentation/manual/src/main/docbook/en-US/content/basic_mapping.xml
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@ -1877,10 +1877,77 @@ public String getId() {</programlisting>
<term><literal>uuid</literal></term>
<listitem>
<para>uses a 128-bit UUID algorithm to generate identifiers
of type string that are unique within a network (the IP
address is used). The UUID is encoded as a string of 32
hexadecimal digits in length.</para>
<para>Generates a 128-bit UUID based on a custom algorithm.
The value generated is represented as a string of 32
hexidecimal digits. Users can also configure it to use a
separator (config parameter "separator") which separates the
hexidecimal digits into 8{sep}8{sep}4{sep}8{sep}4. Note
specifically that this is different than the IETF RFC 4122
representation of 8-4-4-4-12. If you need RFC 4122 compliant
UUIDs, consider using "uuid2" generator discussed
below.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>uuid2</literal></term>
<listitem>
<para>Generates a IETF RFC 4122 compliant (variant 2)
128-bit UUID. The exact "version" (the RFC term) generated
depends on the pluggable "generation strategy" used (see
below). Capable of generating values as
<classname>java.util.UUID</classname>,
<classname>java.lang.String</classname> or as a byte array
of length 16 (<literal>byte[16]</literal>). The "generation
strategy" is defined by the interface
<interfacename>org.hibernate.id.UUIDGenerationStrategy</interfacename>.
The generator defines 2 configuration parameters for
defining which generation strategy to use: <variablelist>
<varlistentry>
<term><literal>uuid_gen_strategy_class</literal></term>
<listitem>
<para>Names the UUIDGenerationStrategy class to
use</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>uuid_gen_strategy</literal></term>
<listitem>
<para>Names the UUIDGenerationStrategy instance to
use</para>
</listitem>
</varlistentry>
</variablelist></para>
<para>Out of the box, comes with the following strategies:
<itemizedlist>
<listitem>
<para><classname>org.hibernate.id.uuid.StandardRandomStrategy</classname>
(the default) - generates "version 3" (aka, "random")
UUID values via the
<methodname>randomUUID</methodname> method of
<classname>java.util.UUID</classname></para>
</listitem>
<listitem>
<para><classname>org.hibernate.id.uuid.CustomVersionOneStrategy</classname>
- generates "version 1" UUID values, using IP address
since mac address not available. If you need mac
address to be used, consider leveraging one of the
existing third party UUID generators which sniff out
mac address and integrating it via the
<interfacename>org.hibernate.id.UUIDGenerationStrategy</interfacename>
contract. Two such libraries known at time of this
writing include <ulink
url="http://johannburkard.de/software/uuid/">http://johannburkard.de/software/uuid/</ulink>
and <ulink
url="http://commons.apache.org/sandbox/id/uuid.html">http://commons.apache.org/sandbox/id/uuid.html</ulink></para>
</listitem>
</itemizedlist></para>
</listitem>
</varlistentry>