JpaDialect (Spring Framework API 2.0) - Spring Framework 2.0.5 API 文档英文版

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org.springframework.orm.jpa
Interface JpaDialect

All Superinterfaces:: PersistenceExceptionTranslator

All Known Implementing Classes:: DefaultJpaDialect, HibernateJpaDialect, OpenJpaDialect, TopLinkJpaDialect

public interface JpaDialect
extends PersistenceExceptionTranslator
extends PersistenceExceptionTranslator

SPI strategy that encapsulates certain functionality that standard JPA 1.0 does not offer, such as access to the underlying JDBC Connection. This strategy is mainly intended for standalone usage of a JPA provider; most of its functionality is not relevant when running with JTA transactions.

Also allows for the provision of value-added methods for portable yet more capable EntityManager and EntityManagerFactory subinterfaces offered by Spring.

In general, it is recommended to derive from DefaultJpaDialect instead of implementing this interface directly. This allows for inheriting common behavior (present and future) from DefaultJpaDialect, only overriding specific hooks to plug in concrete vendor-specific behavior.

Since:: 2.0
Author:: Juergen Hoeller, Rod Johnson
See Also:: DefaultJpaDialect, JpaAccessor.setJpaDialect(org.springframework.orm.jpa.JpaDialect), JpaTransactionManager.setJpaDialect(org.springframework.orm.jpa.JpaDialect), JpaVendorAdapter.getJpaDialect(), AbstractEntityManagerFactoryBean.setJpaDialect(org.springframework.orm.jpa.JpaDialect), AbstractEntityManagerFactoryBean.setJpaVendorAdapter(org.springframework.orm.jpa.JpaVendorAdapter)

Method Summary

Object beginTransaction(javax.persistence.EntityManager entityManager, TransactionDefinition definition)
          Begin the given JPA transaction, applying the semantics specified by the given Spring transaction definition (in particular, an isolation level and a timeout).

void cleanupTransaction(Object transactionData)
          Clean up the transaction via the given transaction data.

EntityManagerFactoryPlusOperations getEntityManagerFactoryPlusOperations(javax.persistence.EntityManagerFactory rawEntityManager)
          Return an EntityManagerFactoryPlusOperations implementation for the given raw EntityManagerFactory.

EntityManagerPlusOperations getEntityManagerPlusOperations(javax.persistence.EntityManager rawEntityManager)
          Return an EntityManagerPlusOperations implementation for the given raw EntityManager.

ConnectionHandle getJdbcConnection(javax.persistence.EntityManager entityManager, boolean readOnly)
          Retrieve the JDBC Connection that the given JPA EntityManager uses underneath, if accessing a relational database.

void releaseJdbcConnection(ConnectionHandle conHandle, javax.persistence.EntityManager entityManager)
          Release the given JDBC Connection, which has originally been retrieved via getJdbcConnection.

boolean supportsEntityManagerFactoryPlusOperations()
          Return whether the EntityManagerFactoryPlus(Operations) interface is supported by this provider.

boolean supportsEntityManagerPlusOperations()
          Return whether the EntityManagerPlus(Operations) interface is supported by this provider.

Methods inherited from interface org.springframework.dao.support.PersistenceExceptionTranslator

translateExceptionIfPossible

Method Summary
`Object`	`beginTransaction(javax.persistence.EntityManager entityManager, TransactionDefinition definition)` Begin the given JPA transaction, applying the semantics specified by the given Spring transaction definition (in particular, an isolation level and a timeout).
`void`	`cleanupTransaction(Object transactionData)` Clean up the transaction via the given transaction data.
`EntityManagerFactoryPlusOperations`	`getEntityManagerFactoryPlusOperations(javax.persistence.EntityManagerFactory rawEntityManager)` Return an EntityManagerFactoryPlusOperations implementation for the given raw EntityManagerFactory.
`EntityManagerPlusOperations`	`getEntityManagerPlusOperations(javax.persistence.EntityManager rawEntityManager)` Return an EntityManagerPlusOperations implementation for the given raw EntityManager.
`ConnectionHandle`	`getJdbcConnection(javax.persistence.EntityManager entityManager, boolean readOnly)` Retrieve the JDBC Connection that the given JPA EntityManager uses underneath, if accessing a relational database.
`void`	`releaseJdbcConnection(ConnectionHandle conHandle, javax.persistence.EntityManager entityManager)` Release the given JDBC Connection, which has originally been retrieved via `getJdbcConnection`.
`boolean`	`supportsEntityManagerFactoryPlusOperations()` Return whether the EntityManagerFactoryPlus(Operations) interface is supported by this provider.
`boolean`	`supportsEntityManagerPlusOperations()` Return whether the EntityManagerPlus(Operations) interface is supported by this provider.

Methods inherited from interface org.springframework.dao.support.PersistenceExceptionTranslator
`translateExceptionIfPossible`

Method Detail

supportsEntityManagerFactoryPlusOperations

boolean supportsEntityManagerFactoryPlusOperations()

Return whether the EntityManagerFactoryPlus(Operations) interface is supported by this provider.

See Also:: EntityManagerFactoryPlusOperations, EntityManagerFactoryPlus

supportsEntityManagerPlusOperations

boolean supportsEntityManagerPlusOperations()

Return whether the EntityManagerPlus(Operations) interface is supported by this provider.

See Also:: EntityManagerPlusOperations, EntityManagerPlus

getEntityManagerFactoryPlusOperations

EntityManagerFactoryPlusOperations getEntityManagerFactoryPlusOperations(javax.persistence.EntityManagerFactory rawEntityManager)

Return an EntityManagerFactoryPlusOperations implementation for the given raw EntityManagerFactory. This operations object can be used to serve the additional operations behind a proxy that implements the EntityManagerFactoryPlus interface.

Parameters:: rawEntityManager - the raw provider-specific EntityManagerFactory
Returns:: the EntityManagerFactoryPlusOperations implementation

getEntityManagerPlusOperations

EntityManagerPlusOperations getEntityManagerPlusOperations(javax.persistence.EntityManager rawEntityManager)

Return an EntityManagerPlusOperations implementation for the given raw EntityManager. This operations object can be used to serve the additional operations behind a proxy that implements the EntityManagerPlus interface.

Parameters:: rawEntityManager - the raw provider-specific EntityManagerFactory
Returns:: the EntityManagerFactoryPlusOperations implementation

beginTransaction

Object beginTransaction(javax.persistence.EntityManager entityManager,
                        TransactionDefinition definition)
                        throws javax.persistence.PersistenceException,
                               SQLException,
                               TransactionException

Begin the given JPA transaction, applying the semantics specified by the given Spring transaction definition (in particular, an isolation level and a timeout). Invoked by JpaTransactionManager on transaction begin.

An implementation can configure the JPA Transaction object and then invoke begin, or invoke a special begin method that takes, for example, an isolation level.

An implementation can also apply read-only flag and isolation level to the underlying JDBC Connection before beginning the transaction. In that case, a transaction data object can be returned that holds the previous isolation level (and possibly other data), to be reset in cleanupTransaction.

Implementations can also use the Spring transaction name, as exposed by the passed-in TransactionDefinition, to optimize for specific data access use cases (effectively using the current transaction name as use case identifier).

Parameters:: entityManager - the EntityManager to begin a JPA transaction on; definition - the Spring transaction definition that defines semantics
Returns:: an arbitrary object that holds transaction data, if any (to be passed into cleanupTransaction)
Throws:: javax.persistence.PersistenceException - if thrown by JPA methods; SQLException - if thrown by JDBC methods; TransactionException - in case of invalid arguments
See Also:: cleanupTransaction(java.lang.Object), EntityTransaction.begin(), DataSourceUtils.prepareConnectionForTransaction(java.sql.Connection, org.springframework.transaction.TransactionDefinition)

cleanupTransaction

void cleanupTransaction(Object transactionData)

Clean up the transaction via the given transaction data. Invoked by JpaTransactionManager on transaction cleanup.

An implementation can, for example, reset read-only flag and isolation level of the underlying JDBC Connection. Furthermore, an exposed data access use case can be reset here.

Parameters:: transactionData - arbitrary object that holds transaction data, if any (as returned by beginTransaction)
See Also:: beginTransaction(javax.persistence.EntityManager, org.springframework.transaction.TransactionDefinition), DataSourceUtils.resetConnectionAfterTransaction(java.sql.Connection, java.lang.Integer)

getJdbcConnection

ConnectionHandle getJdbcConnection(javax.persistence.EntityManager entityManager,
                                   boolean readOnly)
                                   throws javax.persistence.PersistenceException,
                                          SQLException

Retrieve the JDBC Connection that the given JPA EntityManager uses underneath, if accessing a relational database. This method will just get invoked if actually needing access to the underlying JDBC Connection, usually within an active JPA transaction (for example, by JpaTransactionManager). The returned handle will be passed into the releaseJdbcConnection method when not needed anymore.

This strategy is necessary as JPA 1.0 does not provide a standard way to retrieve the underlying JDBC Connection (due to the fact that a JPA implementation might not work with a relational database at all).

Implementations are encouraged to return an unwrapped Connection object, i.e. the Connection as they got it from the connection pool. This makes it easier for application code to get at the underlying native JDBC Connection, like an OracleConnection, which is sometimes necessary for LOB handling etc. We assume that calling code knows how to properly handle the returned Connection object.

In a simple case where the returned Connection will be auto-closed with the EntityManager or can be released via the Connection object itself, an implementation can return a SimpleConnectionHandle that just contains the Connection. If some other object is needed in releaseJdbcConnection, an implementation should use a special handle that references that other object.

Parameters:: entityManager - the current JPA EntityManager
Returns:: a handle for the JDBC Connection, to be passed into releaseJdbcConnection, or null if no JDBC Connection can be retrieved
Throws:: javax.persistence.PersistenceException - if thrown by JPA methods; SQLException - if thrown by JDBC methods
See Also:: releaseJdbcConnection(org.springframework.jdbc.datasource.ConnectionHandle, javax.persistence.EntityManager), ConnectionHandle.getConnection(), SimpleConnectionHandle, JpaTransactionManager.setDataSource(javax.sql.DataSource), NativeJdbcExtractor

releaseJdbcConnection

void releaseJdbcConnection(ConnectionHandle conHandle,
                           javax.persistence.EntityManager entityManager)
                           throws javax.persistence.PersistenceException,
                                  SQLException

Release the given JDBC Connection, which has originally been retrieved via getJdbcConnection. This should be invoked in any case, to allow for proper release of the retrieved Connection handle.

An implementation might simply do nothing, if the Connection returned by getJdbcConnection will be implicitly closed when the JPA transaction completes or when the EntityManager is closed.

Parameters:: conHandle - the JDBC Connection handle to release; entityManager - the current JPA EntityManager
Throws:: javax.persistence.PersistenceException - if thrown by JPA methods; SQLException - if thrown by JDBC methods
See Also:: getJdbcConnection(javax.persistence.EntityManager, boolean)