org.exolab.castor.jdo.keygen
Class MaxKeyGeneratorFactory

java.lang.Object
  org.exolab.castor.jdo.keygen.MaxKeyGeneratorFactory

All Implemented Interfaces:

KeyGeneratorFactory

public final class MaxKeyGeneratorFactory

extends java.lang.Object

implements KeyGeneratorFactory

MAX key generator factory. The short name of this key generator is "MAX". It uses the following alrorithm: the maximum value of the primary key is fetched and the correspondent record is locked until the end of transaction, generator returns (max + 1). The lock guarantees that key generators of concurrent transactions will not use this key value, so DuplicateKeyException is impossible. If the table is empty, generator returns 1, no lock is put, DuplicateKeyException is possible.

Version:

$Revision: 7121 $ $Date: 2005-06-01 06:08:22 -0600 (Wed, 01 Jun 2005) $

Author:

Oleg Nitz

See Also:

MaxKeyGenerator

Constructor Summary

MaxKeyGeneratorFactory()

Method Summary

KeyGenerator	getKeyGenerator(PersistenceFactory factory, java.util.Properties params, int sqlType) Produce the key generator.
java.lang.String	getName() The short name of this key generator is "MAX".

Methods inherited from class java.lang.Object

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

Constructor Detail

MaxKeyGeneratorFactory

public MaxKeyGeneratorFactory()

Method Detail

getKeyGenerator

public KeyGenerator getKeyGenerator(PersistenceFactory factory,
                                    java.util.Properties params,
                                    int sqlType)
                             throws org.exolab.castor.mapping.MappingException

Produce the key generator.

Specified by:

getKeyGenerator in interface KeyGeneratorFactory

Parameters:

factory - Helper object for obtaining database-specific QuerySyntax.

params - Parameters for key generator.

sqlType - The SQL type of the primary key, the generated identities must have the corresponding Java type, e.g. java.sql.Types.INTEGER corresponds to java.lang.Integer, java.sql.Types.NUMERIC corresponds to java.lang.BigDecimal.

Throws:

org.exolab.castor.mapping.MappingException

getName

public java.lang.String getName()

The short name of this key generator is "MAX".

Specified by:

getName in interface KeyGeneratorFactory