Class HighLowKeyGeneratorFactory

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

public final class HighLowKeyGeneratorFactory extends Object implements KeyGeneratorFactory
HIGH-LOW key generator factory. The short name of this key generator is "HIGH-LOW".
It uses the following alrorithm: a special sequence table must be in the database which keeps the maximum key values. The name of the sequence table is a mandatory parameter of the key generator, the parameter name is "table". The name of the primary key column of the sequence table and the name of the column in which maximum values are stored are mandatory parameters with the names "key-column" and "value-column", respectively. The key column contains table names, so it must be of a character type (char or varchar). The value column contains primary key values, it must be of a numeric type (numeric or int). Key generator reads the maximum value X for the given table, writes the new value (X + N) to the sequence table and during next N calls returns values X + 1, ..., X + N without database access. Number N called "grab size" is an optional parameter of the key generator, its parameter name is "grab-size", default value is "10". For example, if you want to obtain HIGH-LOW key generator with 3 digits in the LOW part of the key, you should set "grab-size" to "1000".
Version:
$Revision: 8093 $ $Date: 2006-04-25 15:08:23 -0600 (Tue, 25 Apr 2006) $
Author:
Oleg Nitz, Ralf Joachim
See Also:
  • Constructor Details

    • HighLowKeyGeneratorFactory

      public HighLowKeyGeneratorFactory()
  • 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.