Configuring Multiple Persistence Units In JPA In Same XML File
jpa, spring
Solution
Spring offers the PersistenceUnitManager to act as a central repository and avoid the (potentially expensive) persistence units discovery process . The default implementation allows multiple locations to be specified .
<bean id="pum" class="org.springframework.orm.jpa.persistenceunit.DefaultPersistenceUnitManager">
<property name="persistenceXmlLocation">
<list>
<value>org/springframework/orm/jpa/domain/persistence-multi.xml</value>
<value>classpath:/my/package/**/custom-persistence.xml</value>
<value>classpath*:META-INF/persistence.xml</value>
</list>
</property>
</bean>
<bean id="emf" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="persistenceUnitManager" ref="pum"/>
</bean>
Source - Spring orm jpa
Problem
I have two databases A,B.I have a table called asample in database A and bsample in database B. Now I want to transfer the data from bsample table of B database to asample table of A database. For this I have to use two persistence units in my persistence.xml file. I am using JPA, Spring. I am new to jpa. Can anyone tell me how can I achieve this. If I use the below mentioned code I am getting this exception: ``` ERROR: org.springframework.web.servlet.DispatcherServlet - Context initialization failed org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor#0' defined in ServletContext resource [/WEB-INF/classes/META-INF/spring-context/dao-DB1.xml]: Initialization of bean failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'mediationEntityManagerFactory' defined in ServletContext resource [/WEB-INF/classes/META-INF/spring-context/dao-DB2.xml]: Invocation of init method failed; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: DB2] Unable to build EntityManagerFactory at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:527) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456) at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:291) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:288) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194) at org.springframework.context.support.AbstractApplicationContext.registerBeanPostProcessors(AbstractApplicationContext.java:710) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:410) at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:442) at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:458) at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:339) at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:306) at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:127) at javax.servlet.GenericServlet.init(GenericServlet.java:160) at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1266) at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1185) at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1080) at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:5015) at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5302) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1566) at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1556) at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334) at java.util.concurrent.FutureTask.run(FutureTask.java:166) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) at java.lang.Thread.run(Thread.java:722) Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'mediationEntityManagerFactory' defined in ServletContext resource [/WEB-INF/classes/META-INF/spring-context/dao-DB2.xml]: Invocation of init method failed; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: DB2] Unable to build EntityManagerFactory at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1420) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456) at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:291) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:288) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194) at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeansOfType(DefaultListableBeanFactory.java:398) at org.springframework.beans.factory.BeanFactoryUtils.beansOfTypeIncludingAncestors(BeanFactoryUtils.java:275) at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.detectPersistenceExceptionTranslators(PersistenceExceptionTranslationInterceptor.java:139) at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.<init>(PersistenceExceptionTranslationInterceptor.java:79) at org.springframework.dao.annotation.PersistenceExceptionTranslationAdvisor.<init>(PersistenceExceptionTranslationAdvisor.java:70) at org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor.setBeanFactory(PersistenceExceptionTranslationPostProcessor.java:99) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeAwareMethods(AbstractAutowireCapableBeanFactory.java:1439) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1408) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519) ... 26 more Caused by: javax.persistence.PersistenceException: [PersistenceUnit: DB2] Unable to build EntityManagerFactory at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:900) at org.hibernate.ejb.HibernatePersistence.createContainerEntityManagerFactory(HibernatePersistence.java:74) at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:225) at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:308) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1477) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1417) ... 41 more ``` Iplaced the two persistence units in my persistence.xml file and I have two dao files as dao-DB1.xml, dao-DB2.xml there I am configuring the EntityManager as mentioned in the answer.