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MultipleHiLoPerTableGenerator (Hibernate API Documentation) - Hibernate 3.2.4 正式版 API 英文文档

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org.hibernate.id
Class MultipleHiLoPerTableGenerator

java.lang.Object
  org.hibernate.engine.TransactionHelper
      org.hibernate.id.MultipleHiLoPerTableGenerator

All Implemented Interfaces:

Configurable, IdentifierGenerator, PersistentIdentifierGenerator

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public class MultipleHiLoPerTableGenerator

extends TransactionHelper

implements PersistentIdentifierGenerator, Configurable

A hilo IdentifierGenerator that returns a Long, constructed using a hi/lo algorithm. The hi value MUST be fetched in a seperate transaction to the Session transaction so the generator must be able to obtain a new connection and commit it. Hence this implementation may not be used when the user is supplying connections. In this case a SequenceHiLoGenerator would be a better choice (where supported).

A hilo IdentifierGenerator that uses a database table to store the last generated values. A table can contains several hi values. They are distinct from each other through a key

This implementation is not compliant with a user connection

Allowed parameters (all of them are optional):

• table: table name (default hibernate_sequences)
• primary_key_column: key column name (default sequence_name)
• value_column: hi value column name(default sequence_next_hi_value)
• primary_key_value: key value for the current entity (default to the entity's primary table name)
• primary_key_length: length of the key column in DB represented as a varchar (default to 255)
• max_lo: max low value before increasing hi (default to Short.MAX_VALUE)

Author:

Emmanuel Bernard, Klaus Richarz.

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Field Summary
static String	DEFAULT_TABLE
static String	ID_TABLE
static String	MAX_LO
static String	PK_COLUMN_NAME
static String	PK_LENGTH_NAME
static String	PK_VALUE_NAME
static String	VALUE_COLUMN_NAME

 

Fields inherited from interface org.hibernate.id.PersistentIdentifierGenerator

CATALOG, PK, SCHEMA, SQL, TABLE, TABLES

 

Fields inherited from interface org.hibernate.id.IdentifierGenerator

ENTITY_NAME

 

Constructor Summary

MultipleHiLoPerTableGenerator()

 

Method Summary
void	configure(Type type, Properties params, Dialect dialect)           Configure this instance, given the value of parameters specified by the user as <param> elements.
Serializable	doWorkInCurrentTransaction(Connection conn, String sql)           The work to be done
Serializable	generate(SessionImplementor session, Object obj)           Generate a new identifier.
Object	generatorKey()           Return a key unique to the underlying database objects.
String[]	sqlCreateStrings(Dialect dialect)           The SQL required to create the underlying database objects.
String[]	sqlDropStrings(Dialect dialect)           The SQL required to remove the underlying database objects.

 

Methods inherited from class org.hibernate.engine.TransactionHelper

doWorkInNewTransaction

 

Methods inherited from class java.lang.Object

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

 

Field Detail

ID_TABLE

public static final String ID_TABLE

See Also:

Constant Field Values

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PK_COLUMN_NAME

public static final String PK_COLUMN_NAME

See Also:

Constant Field Values

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PK_VALUE_NAME

public static final String PK_VALUE_NAME

See Also:

Constant Field Values

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VALUE_COLUMN_NAME

public static final String VALUE_COLUMN_NAME

See Also:

Constant Field Values

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PK_LENGTH_NAME

public static final String PK_LENGTH_NAME

See Also:

Constant Field Values

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DEFAULT_TABLE

public static final String DEFAULT_TABLE

See Also:

Constant Field Values

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MAX_LO

public static final String MAX_LO

See Also:

Constant Field Values

Constructor Detail

MultipleHiLoPerTableGenerator

public MultipleHiLoPerTableGenerator()

Method Detail

sqlCreateStrings

public String[] sqlCreateStrings(Dialect dialect)
                          throws HibernateException

Description copied from interface: PersistentIdentifierGenerator

The SQL required to create the underlying database objects.

Specified by:

sqlCreateStrings in interface PersistentIdentifierGenerator

Parameters:

dialect -

Returns:

String[]

Throws:

HibernateException

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sqlDropStrings

public String[] sqlDropStrings(Dialect dialect)
                        throws HibernateException

Description copied from interface: PersistentIdentifierGenerator

The SQL required to remove the underlying database objects.

Specified by:

sqlDropStrings in interface PersistentIdentifierGenerator

Parameters:

dialect -

Returns:

String

Throws:

HibernateException

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generatorKey

public Object generatorKey()

Description copied from interface: PersistentIdentifierGenerator

Return a key unique to the underlying database objects. Prevents us from trying to create/remove them multiple times.

Specified by:

generatorKey in interface PersistentIdentifierGenerator

Returns:

Object an identifying key for this generator

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doWorkInCurrentTransaction

public Serializable doWorkInCurrentTransaction(Connection conn,
                                               String sql)
                                        throws SQLException

Description copied from class: TransactionHelper

The work to be done

Specified by:

doWorkInCurrentTransaction in class TransactionHelper

Throws:

SQLException

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generate

public Serializable generate(SessionImplementor session,
                             Object obj)
                      throws HibernateException

Description copied from interface: IdentifierGenerator

Generate a new identifier.

Specified by:

generate in interface IdentifierGenerator

Parameters:

session -

obj - the entity or toplevel collection for which the id is being generated

Returns:

a new identifier

Throws:

HibernateException

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configure

public void configure(Type type,
                      Properties params,
                      Dialect dialect)
               throws MappingException

Description copied from interface: Configurable

Configure this instance, given the value of parameters specified by the user as <param> elements. This method is called just once, following instantiation.

Specified by:

configure in interface Configurable

Parameters:

params - param values, keyed by parameter name

Throws:

MappingException

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