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How to get entitymanager programming interface in Spring?

I am trying to integrate our DAO maven module in spring, we do not want to change any dao code. Previously, all dao classes get an entity manager as follows.

Persistence.getEntityManager()

In spring, I see many examples that use annotation to enter entity manager, but need to change the dao code. Is there a way to change the class below to make it work in spring?

  public class PersistenceManager { /** * Key that stores the entity manager. */ private static final String ENTITY_MANAGER_INSTANCE = "ENTITY_MANAGER_INSTANCE"; /** * Persistence unit for eMyEd */ private static final String PERSISTENCE_UNIT_EMYED = "application_openjpa"; /** * The static factory used across the JVM */ private static final EntityManagerFactory ENTITY_MANAGER_FACTORY = Persistence .createEntityManagerFactory(PERSISTENCE_UNIT_EMYED); /** * Cleanup any entity managers created in the thread context. */ public static void close() { EntityManager emInstance = getEntityManager(); try { if (emInstance.isOpen()) { emInstance.close(); } } catch (Throwable t) { // ignore } finally { ThreadContext.instance.clear(); } } /** * Returns the Entity manager associated with the given thread context. If * none available, one is created and set on the thread context and the same * is returned. * * @return */ public static EntityManager getEntityManager() { EntityManager emInstance = (EntityManager) ThreadContext.instance .get(ENTITY_MANAGER_INSTANCE); if (emInstance == null) { emInstance = createEntityManager(); emInstance.setFlushMode(FlushModeType.COMMIT); ThreadContext.instance.put(ENTITY_MANAGER_INSTANCE, emInstance); } try { // try to join the current active transaction emInstance.joinTransaction(); } catch (TransactionRequiredException notSupportedEx) { // If there was no transaction to join. Ignore } catch (Throwable unknownEx) { // If there was no transaction to join. Ignore } return emInstance; } /** * Create a new entity manager. * * @return */ private static EntityManager createEntityManager() { return ENTITY_MANAGER_FACTORY.createEntityManager(); } }

Spring Configuration

 <description>Example configuration to get you started.</description> <context:component-scan base-package="com.veera" /> <!-- tell Spring that it should act on any @PersistenceContext and @Transactional annotations found in bean classes --> <tx:annotation-driven transaction-manager="transactionManager" /> <!-- ******************************************************************** --> <!-- Setup the transaction manager --> <!-- ******************************************************************** --> <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager"> <property name="entityManagerFactory" ref="entityManagerFactory" /> </bean> <!-- ******************************************************************** --> <!-- Setup each data source --> <!-- ******************************************************************** --> <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource"> <property name="driverClassName" value="com.mysql.jdbc.Driver" /> <property name="url" value="jdbc:mysql://localhost:3306/test" /> <property name="username" value="root" /> <property name="password" value="root" /> </bean> <!-- ******************************************************************** --> <!-- Setup each persistence unit --> <!-- ******************************************************************** --> <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"> <property name="dataSource" ref="dataSource" /> <property name="jpaVendorAdapter"> <bean class="org.springframework.orm.jpa.vendor.OpenJpaVendorAdapter"> <property name="databasePlatform" value="org.apache.openjpa.jdbc.sql.MySQLDictionary" /> </bean> </property> <property name="persistenceUnitName" value="application_openjpa" /> <!-- property name="loadTimeWeaver"> <bean class="org.springframework.instrument.classloading.InstrumentationLoadTimeWeaver" /> </property --> <!-- property name="jpaProperties"> <props> <prop key="hibernate.hbm2ddl.auto">create-drop</prop> <prop key="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</prop> </props> </property --> </bean> <bean class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor" />

persistence.xml

  <persistence-unit name="application_openjpa" transaction-type="RESOURCE_LOCAL"> <provider>org.apache.openjpa.persistence.PersistenceProviderImpl</provider> <class>com.veera.jpa.Item</class> <class>com.veera.jpa.Order</class> <class>com.zreflect.emyed.entity.user.User</class> <exclude-unlisted-classes>true</exclude-unlisted-classes> <properties> <!-- property name="openjpa.jdbc.SynchronizeMappings" value="buildSchema" / <property name="openjpa.InitializeEagerly" value="true"/--> <property name="openjpa.Log" value="File=stdout, DefaultLevel=INFO, Runtime=INFO, SQL=TRACE"/> </properties> </persistence-unit> </persistence>
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2 answers

Since the definition of EntityManager by definition is not thread safe, the only - yet ugly solution is to save the EntityManagerFactory statically and instantiate EntityManager from the factory on request.

I even suggest changing the DAO to use the dependency injection reason with this approach, your DAOs essentially become un-unittestable without loading the entire JPA infrastructure.

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I found a solution, see below

Update

  @Repository public class PersistenceManager { /** * Key that stores the entity manager. */ private static final String ENTITY_MANAGER_INSTANCE = "ENTITY_MANAGER_INSTANCE"; /** * Persistence unit for eMyEd */ private static final String PERSISTENCE_UNIT_EMYED = "application_openjpa"; private static EntityManagerFactory emf; @PersistenceUnit(unitName=PERSISTENCE_UNIT_EMYED) public void setEntityManagerFactory(EntityManagerFactory emf) { PersistenceManager.emf = emf; } /** * Cleanup any entity managers created in the thread context. */ public static void close() { EntityManager emInstance = getEntityManager(); try { if (emInstance.isOpen()) { emInstance.close(); } } catch (Throwable t) { // ignore } finally { ThreadContext.instance.clear(); } } /** * Returns the Entity manager associated with the given thread context. If * none available, one is created and set on the thread context and the same * is returned. * * @return */ public static EntityManager getEntityManager() { EntityManager emInstance = (EntityManager) ThreadContext.instance .get(ENTITY_MANAGER_INSTANCE); if (emInstance == null) { emInstance = createEntityManager(); emInstance.setFlushMode(FlushModeType.COMMIT); ThreadContext.instance.put(ENTITY_MANAGER_INSTANCE, emInstance); } try { // try to join the current active transaction emInstance.joinTransaction(); } catch (TransactionRequiredException notSupportedEx) { // If there was no transaction to join. Ignore } catch (Throwable unknownEx) { // If there was no transaction to join. Ignore } return emInstance; } /** * Create a new entity manager. * * @return */ private static EntityManager createEntityManager() { return emf.createEntityManager(); } }
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Source: https://habr.com/ru/post/1501031/

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