org.springframework.orm.jpa
Class JpaTemplate

java.lang.Object
  org.springframework.orm.jpa.EntityManagerFactoryAccessor
      org.springframework.orm.jpa.JpaAccessor
          org.springframework.orm.jpa.JpaTemplate

All Implemented Interfaces:

InitializingBean, JpaOperations

public class JpaTemplate
extends JpaAccessor
implements JpaOperations

Helper class that allows for writing JPA data access code in the same style as with Spring's well-known JdoTemplate and HibernateTemplate classes. Automatically converts PersistenceExceptions into Spring DataAccessExceptions, following the org.springframework.dao exception hierarchy.

The central method is of this template is "execute", supporting JPA access code implementing the JpaCallback interface. It provides JPA EntityManager handling such that neither the JpaCallback implementation nor the calling code needs to explicitly care about retrieving/closing EntityManagers, or handling JPA lifecycle exceptions.

Can be used within a service implementation via direct instantiation with a EntityManagerFactory reference, or get prepared in an application context and given to services as bean reference. Note: The EntityManagerFactory should always be configured as bean in the application context, in the first case given to the service directly, in the second case to the prepared template.

NOTE: JpaTemplate mainly exists as a sibling of JdoTemplate and HibernateTemplate, offering the same style for people used to it. For newly started projects, consider adopting the standard JPA style of coding data access objects instead, based on a "shared EntityManager" reference injected via a Spring bean definition or the JPA PersistenceContext annotation. (Using Spring's SharedEntityManagerBean / PersistenceAnnotationBeanPostProcessor, or using a direct JNDI lookup for an EntityManager on a Java EE 5 server.)

JpaTemplate can be considered as direct alternative to working with the native JPA EntityManager API (through a shared EntityManager reference, as outlined above). The major advantage is its automatic conversion to DataAccessExceptions; the major disadvantage is that it introduces another thin layer on top of the native JPA API. Note that exception translation can also be achieved through AOP advice; check out PersistenceExceptionTranslationPostProcessor.

LocalContainerEntityManagerFactoryBean is the preferred way of obtaining a reference to an EntityManagerFactory, at least outside of a full Java EE 5 environment. The Spring application context will manage its lifecycle, initializing and shutting down the factory as part of the application. Within a Java EE 5 environment, you will typically work with a server-managed EntityManagerFactory that is exposed via JNDI, obtained through Spring's JndiObjectFactoryBean.

Since:

2.0

Author:

Juergen Hoeller

See Also:

EntityManagerFactoryAccessor.setEntityManagerFactory(javax.persistence.EntityManagerFactory), JpaCallback, EntityManager, LocalEntityManagerFactoryBean, LocalContainerEntityManagerFactoryBean, JpaTransactionManager, JtaTransactionManager, OpenEntityManagerInViewFilter, OpenEntityManagerInViewInterceptor

Field Summary

Fields inherited from class org.springframework.orm.jpa.EntityManagerFactoryAccessor

logger

Constructor Summary

JpaTemplate()
Create a new JpaTemplate instance.

JpaTemplate(javax.persistence.EntityManager em)
Create a new JpaTemplate instance.

JpaTemplate(javax.persistence.EntityManagerFactory emf)
Create a new JpaTemplate instance.

Method Summary

boolean	contains(Object entity)
protected javax.persistence.EntityManager	createEntityManagerProxy(javax.persistence.EntityManager em) Create a close-suppressing proxy for the given JPA EntityManager.
<T> T	execute(JpaCallback<T> action)
<T> T	execute(JpaCallback<T> action, boolean exposeNativeEntityManager) Execute the action specified by the given action object within a EntityManager.
List	executeFind(JpaCallback<?> action)
<T> T	find(Class<T> entityClass, Object id)
List	find(String queryString)
List	find(String queryString, Object... values)
List	findByNamedParams(String queryString, Map<String,?> params)
List	findByNamedQuery(String queryName)
List	findByNamedQuery(String queryName, Object... values)
List	findByNamedQueryAndNamedParams(String queryName, Map<String,?> params)
void	flush()
<T> T	getReference(Class<T> entityClass, Object id)
boolean	isExposeNativeEntityManager() Return whether to expose the native JPA EntityManager to JpaCallback code, or rather an EntityManager proxy.
<T> T	merge(T entity)
void	persist(Object entity)
void	prepareQuery(javax.persistence.Query query) Prepare the given JPA query object.
void	refresh(Object entity)
void	remove(Object entity)
void	setExposeNativeEntityManager(boolean exposeNativeEntityManager) Set whether to expose the native JPA EntityManager to JpaCallback code.

Methods inherited from class org.springframework.orm.jpa.JpaAccessor

afterPropertiesSet, flushIfNecessary, getEntityManager, getJpaDialect, isFlushEager, setEntityManager, setFlushEager, setJpaDialect, translateIfNecessary

Methods inherited from class org.springframework.orm.jpa.EntityManagerFactoryAccessor

createEntityManager, getEntityManagerFactory, getJpaPropertyMap, getTransactionalEntityManager, setEntityManagerFactory, setJpaProperties, setJpaPropertyMap

Methods inherited from class java.lang.Object

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

Constructor Detail

JpaTemplate

public JpaTemplate()

Create a new JpaTemplate instance.

JpaTemplate

public JpaTemplate(javax.persistence.EntityManagerFactory emf)

Create a new JpaTemplate instance.

Parameters:

emf - EntityManagerFactory to create EntityManagers

JpaTemplate

public JpaTemplate(javax.persistence.EntityManager em)

Create a new JpaTemplate instance.

Parameters:

em - EntityManager to use

Method Detail

setExposeNativeEntityManager

public void setExposeNativeEntityManager(boolean exposeNativeEntityManager)

Set whether to expose the native JPA EntityManager to JpaCallback code. Default is "false": a EntityManager proxy will be returned, suppressing close calls and automatically applying transaction timeouts (if any).

As there is often a need to cast to a provider-specific EntityManager class in DAOs that use the JPA 1.0 API, for JPA 2.0 previews and other provider-specific functionality, the exposed proxy implements all interfaces implemented by the original EntityManager. If this is not sufficient, turn this flag to "true".

See Also:

JpaCallback, EntityManager

isExposeNativeEntityManager

public boolean isExposeNativeEntityManager()

Return whether to expose the native JPA EntityManager to JpaCallback code, or rather an EntityManager proxy.

execute

public <T> T execute(JpaCallback<T> action)
          throws DataAccessException

Specified by:

execute in interface JpaOperations

Throws:

DataAccessException

executeFind

public List executeFind(JpaCallback<?> action)
                 throws DataAccessException

Specified by:

executeFind in interface JpaOperations

Throws:

DataAccessException

execute

public <T> T execute(JpaCallback<T> action,
                     boolean exposeNativeEntityManager)
          throws DataAccessException

Execute the action specified by the given action object within a EntityManager.

Parameters:

action - callback object that specifies the JPA action

exposeNativeEntityManager - whether to expose the native JPA entity manager to callback code

Returns:

a result object returned by the action, or null

Throws:

DataAccessException - in case of JPA errors

createEntityManagerProxy

protected javax.persistence.EntityManager createEntityManagerProxy(javax.persistence.EntityManager em)

Create a close-suppressing proxy for the given JPA EntityManager. The proxy also prepares returned JPA Query objects.

Parameters:

em - the JPA EntityManager to create a proxy for

Returns:

the EntityManager proxy, implementing all interfaces implemented by the passed-in EntityManager object (that is, also implementing all provider-specific extension interfaces)

See Also:

EntityManager.close()

find

public <T> T find(Class<T> entityClass,
                  Object id)
       throws DataAccessException

Specified by:

find in interface JpaOperations

Throws:

DataAccessException

getReference

public <T> T getReference(Class<T> entityClass,
                          Object id)
               throws DataAccessException

Specified by:

getReference in interface JpaOperations

Throws:

DataAccessException

contains

public boolean contains(Object entity)
                 throws DataAccessException

Specified by:

contains in interface JpaOperations

Throws:

DataAccessException

refresh

public void refresh(Object entity)
             throws DataAccessException

Specified by:

refresh in interface JpaOperations

Throws:

DataAccessException

persist

public void persist(Object entity)
             throws DataAccessException

Specified by:

persist in interface JpaOperations

Throws:

DataAccessException

merge

public <T> T merge(T entity)
        throws DataAccessException

Specified by:

merge in interface JpaOperations

Throws:

DataAccessException

remove

public void remove(Object entity)
            throws DataAccessException

Specified by:

remove in interface JpaOperations

Throws:

DataAccessException

flush

public void flush()
           throws DataAccessException

Specified by:

flush in interface JpaOperations

Throws:

DataAccessException

find

public List find(String queryString)
          throws DataAccessException

Specified by:

find in interface JpaOperations

Throws:

DataAccessException

find

public List find(String queryString,
                 Object... values)
          throws DataAccessException

Specified by:

find in interface JpaOperations

Throws:

DataAccessException

findByNamedParams

public List findByNamedParams(String queryString,
                              Map<String,?> params)
                       throws DataAccessException

Specified by:

findByNamedParams in interface JpaOperations

Throws:

DataAccessException

findByNamedQuery

public List findByNamedQuery(String queryName)
                      throws DataAccessException

Specified by:

findByNamedQuery in interface JpaOperations

Throws:

DataAccessException

findByNamedQuery

public List findByNamedQuery(String queryName,
                             Object... values)
                      throws DataAccessException

Specified by:

findByNamedQuery in interface JpaOperations

Throws:

DataAccessException

findByNamedQueryAndNamedParams

public List findByNamedQueryAndNamedParams(String queryName,
                                           Map<String,?> params)
                                    throws DataAccessException

Specified by:

findByNamedQueryAndNamedParams in interface JpaOperations

Throws:

DataAccessException

prepareQuery

public void prepareQuery(javax.persistence.Query query)

Prepare the given JPA query object. To be used within a JpaCallback.

Applies a transaction timeout, if any. If you don't use such timeouts, the call is a no-op.

In general, prefer a proxied EntityManager instead, which will automatically apply the transaction timeout (through the use of a special EntityManager proxy). You need to set the "exposeNativeEntityManager" property to "false" to activate this. Note that you won't be able to cast to a provider-specific JPA EntityManager class anymore then.

Parameters:

query - the JPA query object

See Also:

JpaCallback.doInJpa(javax.persistence.EntityManager), EntityManagerFactoryUtils.applyTransactionTimeout(javax.persistence.Query, javax.persistence.EntityManagerFactory), setExposeNativeEntityManager(boolean)