Class HighLowKeyGeneratorFactory
- java.lang.Object
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- org.castor.cpa.persistence.sql.keygen.HighLowKeyGeneratorFactory
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- All Implemented Interfaces:
KeyGeneratorFactory
public final class HighLowKeyGeneratorFactory extends java.lang.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:
HighLowKeyGenerator
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Constructor Summary
Constructors Constructor Description HighLowKeyGeneratorFactory()
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description KeyGenerator
getKeyGenerator(PersistenceFactory factory, java.util.Properties params, int sqlType)
Produce the key generator.java.lang.String
getKeyGeneratorName()
Get the short name of the key generator.
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Method Detail
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getKeyGeneratorName
public java.lang.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 interfaceKeyGeneratorFactory
- Returns:
- Name of the
KeyGenerator
used to identify key generator (types).
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getKeyGenerator
public KeyGenerator getKeyGenerator(PersistenceFactory factory, java.util.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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