Class MaxKeyGeneratorFactory

java.lang.Object
org.castor.cpa.persistence.sql.keygen.MaxKeyGeneratorFactory
All Implemented Interfaces:
KeyGeneratorFactory

public final class MaxKeyGeneratorFactory extends 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: 8093 $ $Date: 2006-04-25 15:08:23 -0600 (Tue, 25 Apr 2006) $
Author:
Oleg Nitz, Ralf Joachim
See Also:
  • Constructor Details

    • MaxKeyGeneratorFactory

      public MaxKeyGeneratorFactory()
  • Method Details

    • getKeyGeneratorName

      public String 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 interface KeyGeneratorFactory
      Returns:
      Name of the KeyGenerator used to identify key generator (types).
    • getKeyGenerator

      public KeyGenerator getKeyGenerator(PersistenceFactory factory, Properties params, int sqlType) throws 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.
      Returns:
      A KeyGenerator instance.
      Throws:
      MappingException - If there's a problem resolving the mapping information.