这篇文章是JPA持久化后如何从数据库获取值的延续
当我执行以下命令时,出现以下异常,我该如何解决这个问题?
Not allowed to create transaction on shared EntityManager - use Spring
transactions or EJB CMT
DAOImpl代码
public void create(Project project) {
entityManager.persist(project);
entityManager.getTransaction().commit();
project = entityManager.find(Project.class, project.getProjectId());
entityManager.refresh(project);
System.out.println("Id -- " + project.getProjectId());
System.out.println("no -- " + project.getProjectNo());
}
applicationContext.xml
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.0.xsd">
<bean id="DataSource"
class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="username" value="scott" />
<property name="password" value="tiger" />
<property name="driverClassName" value="oracle.jdbc.driver.OracleDriver" />
<property name="url" value="jdbc:oracle:thin:@myserver:1521:ORCL" />
</bean>
<bean id="entityManagerFactory"
class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="dataSource" ref="DataSource" />
<property name="packagesToScan" value="test.entity" />
<property name="jpaVendorAdapter">
<bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
<property name="showSql" value="true" />
<property name="generateDdl" value="false" />
<property name="databasePlatform" value="org.hibernate.dialect.Oracle10gDialect" />
</bean>
</property>
</bean>
<context:component-scan base-package="test.net" />
<tx:annotation-driven transaction-manager="transactionManager"/>
<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
<property name="entityManagerFactory" ref="entityManagerFactory" />
</bean>
<context:annotation-config/>
</beans>
我猜这里的问题是,虽然你已经为事务管理器定义了bean,但你没有用
@Transactional
注释create()方法来启用spring事务。
还要删除
entityManager.getTransaction().commit();
语句,因为现在所有事务管理都将由 spring 处理,如果您保留该语句不变,那么您将再次遇到相同的错误。
在方法上注入 EntityManagerFactory 而不是 EntityManager 和 javax.transaction.Transactional 注释解决了我的问题,如下所示。
//Autowire EntityManagerFactory
@PersistenceUnit(unitName = "readwrite.config")
private EntityManagerFactory entityManagerFactory;
//Use below code on create/update
EntityManager entityManager = entityManagerFactory.createEntityManager();
entityManager.getTransaction().begin();
if (!ObjectUtils.isEmpty(entity) && !entityManager.contains(entity)) {
entityManager.persist(entity);
entityManager.flush();
}
entityManager.getTransaction().commit();
您需要删除声明
entityManager.getTransaction().begin() and annotate the method using
@Transactional?这使得 Spring 能够进行事务处理。
就我而言,在 Sping-boot 中这个解决方案有效
@Transactional(propagation = Propagation.NEVER)
public void myMethod() {
SessionImplementor sessionImp = (SessionImplementor) em.getDelegate();
var transaction = sessionImp.getTransaction();
for (MyClass cls : lst) {
try {
transaction.begin();
//do my stuffs with em
transaction.commit();
} catch (Exception e) {
transaction.rollback();
}
}
}
对我来说这有效: 我已在具有相同名称的不同文件中声明了 EntityManager。所以我只是更改了 EntityManager 变量的名称,它就起作用了。 我使用的提示是“共享实例”。
文件1:
//Before:
EntityManager entityManager;
//After:
EntityManager entityManagerrr;
文件2:
//And in the other file it is:
EntityManager entityManager;