public interface

JpaDialect

implements PersistenceExceptionTranslator
org.springframework.orm.jpa.JpaDialect
Known Indirect Subclasses

Class Overview

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.

See Also

Summary

Public Methods
abstract Object beginTransaction(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).
abstract void cleanupTransaction(Object transactionData)
Clean up the transaction via the given transaction data.
abstract EntityManagerFactoryPlusOperations getEntityManagerFactoryPlusOperations(EntityManagerFactory rawEntityManager)
Return an EntityManagerFactoryPlusOperations implementation for the given raw EntityManagerFactory.
abstract EntityManagerPlusOperations getEntityManagerPlusOperations(EntityManager rawEntityManager)
Return an EntityManagerPlusOperations implementation for the given raw EntityManager.
abstract ConnectionHandle getJdbcConnection(EntityManager entityManager, boolean readOnly)
Retrieve the JDBC Connection that the given JPA EntityManager uses underneath, if accessing a relational database.
abstract Object prepareTransaction(EntityManager entityManager, boolean readOnly, String name)
Prepare a JPA transaction, applying the specified semantics.
abstract void releaseJdbcConnection(ConnectionHandle conHandle, EntityManager entityManager)
Release the given JDBC Connection, which has originally been retrieved via getJdbcConnection.
abstract boolean supportsEntityManagerFactoryPlusOperations()
Return whether the EntityManagerFactoryPlus(Operations) interface is supported by this provider.
abstract boolean supportsEntityManagerPlusOperations()
Return whether the EntityManagerPlus(Operations) interface is supported by this provider.
[Expand]
Inherited Methods
From interface org.springframework.dao.support.PersistenceExceptionTranslator

Public Methods

public abstract Object beginTransaction (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). Called 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 apply the read-only flag as flush mode. In that case, a transaction data object can be returned that holds the previous flush mode (and possibly other data), to be reset in cleanupTransaction. It may also apply the read-only flag and isolation level to the underlying JDBC Connection before beginning the transaction.

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).

This method also allows for exposing savepoint capabilities if supported by the persistence provider, through returning an Object that implements Spring's SavepointManager interface. JpaTransactionManager will use this capability if needed.

Parameters
entityManager the EntityManager to begin a JPA transaction on
definition the Spring transaction definition that defines semantics
Returns
Throws
if thrown by JPA methods
SQLException if thrown by JDBC methods
TransactionException in case of invalid arguments
PersistenceException
See Also

public abstract void cleanupTransaction (Object transactionData)

Clean up the transaction via the given transaction data. Called by JpaTransactionManager and EntityManagerFactoryUtils 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 or prepareTransaction)
See Also

public abstract EntityManagerFactoryPlusOperations getEntityManagerFactoryPlusOperations (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

public abstract EntityManagerPlusOperations getEntityManagerPlusOperations (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

public abstract ConnectionHandle getJdbcConnection (EntityManager entityManager, boolean readOnly)

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
readOnly whether the Connection is only needed for read-only purposes
Returns
  • a handle for the JDBC Connection, to be passed into releaseJdbcConnection, or null if no JDBC Connection can be retrieved
Throws
if thrown by JPA methods
SQLException if thrown by JDBC methods
PersistenceException
See Also

public abstract Object prepareTransaction (EntityManager entityManager, boolean readOnly, String name)

Prepare a JPA transaction, applying the specified semantics. Called by EntityManagerFactoryUtils when enlisting an EntityManager in a JTA transaction.

An implementation can apply the read-only flag as flush mode. In that case, a transaction data object can be returned that holds the previous flush mode (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
readOnly whether the transaction is supposed to be read-only
name the name of the transaction (if any)
Returns
  • an arbitrary object that holds transaction data, if any (to be passed into cleanupTransaction)
Throws
if thrown by JPA methods
PersistenceException
See Also

public abstract void releaseJdbcConnection (ConnectionHandle conHandle, EntityManager entityManager)

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
if thrown by JPA methods
SQLException if thrown by JDBC methods
PersistenceException
See Also

public abstract boolean supportsEntityManagerFactoryPlusOperations ()

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

See Also

public abstract boolean supportsEntityManagerPlusOperations ()

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

See Also