在Spring + Hibernate配置中获取EntityManager [英] Obtaining EntityManager in Spring + Hibernate configuration
问题描述
我有一个Spring MVC 4.0应用程序，我正在学习JPA。我使用Hibernate作为JPA实现。
我可以按照这个教程。它工作正常，但我必须使用Hibernate的 Session 对象：
@Autowired
SessionFactory sessionFactory;
...
会话会话= sessionFactory.openSession（）;
现在，我想使用JPA的 EntityManager 代替。我遵循这个教程在同一个网站上（配置非常相似）。我尝试以这种方式获得 EntityManager 对象：
@PersistenceContext
EntityManager entityManager;
我收到了一条运行时消息：
然后，我遵循此答案中的建议，并尝试使用以下代码：
@PersistenceContext
EntityManager entityManager;
...
entityManager = entityManager.getEntityManagerFactory（）。createEntityManager（）;
它可以工作几次（大约9次重复的方法调用），然后应用程序冻结。 p>
在Spring + Hibernate配置中获得 EntityManager 的正确方法是什么？
现在我不需要任何Spring事务功能。我只想访问 EntityManager 并使用JPA。
Spring / Hibernate配置文件（hibernate.xml）
<？xml version =1.0encoding =UTF-8？ >
< beans xmlns =http://www.springframework.org/schema/beans
xmlns：xsi =http://www.w3.org/2001/XMLSchema -instance
xmlns：context =http://www.springframework.org/schema/context
xmlns：tx =http://www.springframework.org/schema/tx
xsi：schemaLocation =http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
http：// www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd
http://www.springframework.org/schema/tx http：/ /www.springframework.org/schema/tx/spring-tx-4.0.xsd\">
< bean id =dataSourceclass =org.apache.tomcat.dbcp.dbcp.BasicDataSource>
< property name =driverClassNamevalue =com.mysql.jdbc.Driver/>
< property name =urlvalue =jdbc：mysql：// localhost：3306 / test_db/>
< property name =usernamevalue =test/>
< property name =passwordvalue =test/>
< / bean>
< bean id =entityManagerFactoryclass =org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean>
< property name =dataSourceref =dataSource/>
< property name =packagesToScanvalue =net.myproject/>
< property name =jpaVendorAdapter>
< bean class =org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter/>
< / property>
< property name =jpaProperties>
<道具>
< prop key =hibernate.hbm2ddl.auto> update< / prop>
< prop key =hibernate.dialect> org.hibernate.dialect.MySQL5Dialect< / prop>
< prop key =hibernate.show_sql> true< / prop>
< /道具>
< / property>
< / bean>
< bean id =transactionManagerclass =org.springframework.orm.jpa.JpaTransactionManager>
< property name =entityManagerFactoryref =entityManagerFactory/>
< / bean>
< bean id =persistenceExceptionTranslationPostProcessorclass =org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor/>
< tx：annotation-driven />
< / beans>
我尝试使用的类 EntityManager
@Repository
public class ProductsService {
@ PersistenceContext
EntityManager entityManager;
@Transactional
public GridResponse< Product> getProducts（GridRequest dRequest）{
//以下行导致异常：java.lang.IllegalStateException：无事务性EntityManager可用
Session session = entityManager.unwrap（Session.class） ;
// ...
}
...
$ b $对于 @PersistenceContext EntityManager entityManager; 方法，添加 tx：annotation -driven 添加到.xml配置中，并将您的方法标记为 @Transactional 。
I have a Spring MVC 4.0 application, and I am learning JPA. I use Hibernate as the JPA implementation.
I can configure Hibernate as described in this tutorial. It works fine, but I have to use Hibernate's Session object:
@Autowired
SessionFactory sessionFactory;
...
Session session = sessionFactory.openSession();
Now, I want to use JPA's EntityManager instead. I have followed this tutorial on the same web site (the configuration is very similar). And I tried to obtain an EntityManager object this way:
@PersistenceContext
EntityManager entityManager;
I got a runtime message:
java.lang.IllegalStateException: No transactional EntityManager available
Then, I followed the suggestion in this answer, and tried to use the following code:
@PersistenceContext
EntityManager entityManager;
...
entityManager=entityManager.getEntityManagerFactory().createEntityManager();
It works a few times (about 9 repetitive method invocations), and then the application freezes.
What is the right way to get EntityManager in Spring + Hibernate configuration?
I do not need any Spring transaction functionality for now. I just want to get an access to EntityManager and play with JPA.
Spring/Hibernate configuration file (hibernate.xml)
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:tx="http://www.springframework.org/schema/tx"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd">
<bean id="dataSource" class="org.apache.tomcat.dbcp.dbcp.BasicDataSource">
<property name="driverClassName" value="com.mysql.jdbc.Driver" />
<property name="url" value="jdbc:mysql://localhost:3306/test_db" />
<property name="username" value="test" />
<property name="password" value="test" />
</bean>
<bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="dataSource" ref="dataSource" />
<property name="packagesToScan" value="net.myproject" />
<property name="jpaVendorAdapter">
<bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter" />
</property>
<property name="jpaProperties">
<props>
<prop key="hibernate.hbm2ddl.auto">update</prop>
<prop key="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</prop>
<prop key="hibernate.show_sql">true</prop>
</props>
</property>
</bean>
<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
<property name="entityManagerFactory" ref="entityManagerFactory" />
</bean>
<bean id="persistenceExceptionTranslationPostProcessor" class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor" />
<tx:annotation-driven />
</beans>
The class where I attempt to use EntityManager
@Repository
public class ProductsService {
@PersistenceContext
EntityManager entityManager;
@Transactional
public GridResponse<Product> getProducts(GridRequest dRequest) {
// The following line causes the exception: "java.lang.IllegalStateException: No transactional EntityManager available"
Session session = entityManager.unwrap(Session.class);
//...
}
...
For the @PersistenceContext EntityManager entityManager; approach, add tx:annotation-driven to your .xml configuration and mark your methods where you use entityManager as @Transactional.
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