Class MaxKeyGeneratorFactory
java.lang.Object
org.castor.cpa.persistence.sql.keygen.MaxKeyGeneratorFactory
- All Implemented Interfaces:
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.
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: 8093 $ $Date: 2006-04-25 15:08:23 -0600 (Tue, 25 Apr 2006) $
- Author:
- Oleg Nitz, Ralf Joachim
- See Also:
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptiongetKeyGenerator
(PersistenceFactory factory, Properties params, int sqlType) Produce the key generator.Get the short name of the key generator.
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Constructor Details
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MaxKeyGeneratorFactory
public MaxKeyGeneratorFactory()
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Method Details
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getKeyGeneratorName
Get the short name of the key generator. It is used to reference key generators in a mapping configuration file. If several key generators of the same type are used for the same database, then they are referenced by aliases.- Specified by:
getKeyGeneratorName
in interfaceKeyGeneratorFactory
- Returns:
- Name of the
KeyGenerator
used to identify key generator (types).
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getKeyGenerator
public KeyGenerator getKeyGenerator(PersistenceFactory factory, Properties params, int sqlType) throws MappingException Produce the key generator.- Specified by:
getKeyGenerator
in interfaceKeyGeneratorFactory
- 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.- Returns:
- A
KeyGenerator
instance. - Throws:
MappingException
- If there's a problem resolving the mapping information.
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