使用 JPA 在 Spring 中进行事务和回滚

Question

StackOverflow 的朋友们好， 我不明白如何回滚我阅读了Spring的文档，但我仍然不明白。基本上我会一直在数据库中保留一个对象（手动使用主键），一直到这里，对象被插入到数据库中。但是，当您使用相同的主键再次持久化对象时，我导致了一个异常，这是正确的，违反了唯一性限制。在这种情况下，我会收到事务回滚并警告您存在问题并继续运行程序

这是我的课：

public class ServiceDaoImpl{

    @PersistenceContext (unitName="fb-persistence")
    protected EntityManager em;

    public void setEntityManager(EntityManager entityManager) {
        this.em = entityManager;
    }

    @Transactional(readOnly=false)
    public void write(Service entity){
        try {
            em.persist(entity);
            em.flush();
        } catch(Exception ex) {
            ex.printStackTrace();
        }
    }

    /*
    * .. other method
    */
}

这是错误堆栈：

javax.persistence.PersistenceException: org.hibernate.exception.ConstraintViolationException: Could not execute JDBC batch update
    at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1214)
    at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1147)
    at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1153)
    at org.hibernate.ejb.AbstractEntityManagerImpl.flush(AbstractEntityManagerImpl.java:798)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:240)
    at $Proxy27.flush(Unknown Source)
    at it.synclab.fb.jpa.dao.impl.GenericDaoImpl.write(GenericDaoImpl.java:236)
    at it.synclab.fb.jpa.dao.impl.EnteDaoImpl.write(EnteDaoImpl.java:1)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:309)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:110)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202)
    at $Proxy34.write(Unknown Source)
    at it.synclab.fb.jpa.test.ConfigTest.insertEnte(ConfigTest.java:47)
    at it.synclab.fb.jpa.test.ConfigTest.main(ConfigTest.java:32)
Caused by: org.hibernate.exception.ConstraintViolationException: Could not execute JDBC batch update
    at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:96)
    at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
    at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:275)
    at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:268)
    at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:184)
    at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:321)
    at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:51)
    at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1216)
    at org.hibernate.ejb.AbstractEntityManagerImpl.flush(AbstractEntityManagerImpl.java:795)
    ... 21 more
Caused by: java.sql.BatchUpdateException: ORA-00001: violata restrizione di unicità (FLUSSIBATCH.SYS_C008896)

而我的配置文件是（persistence.xml 和 applicationContext.xml）：

这是 applicationContext.xml： ...

    <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalEntityManagerFactoryBean">
        <property name="persistenceUnitName" value="fb-persistence" />
    </bean>

    <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager"> 
        <property name="entityManagerFactory" ref="entityManagerFactory"/> 
    </bean>

    <tx:annotation-driven transaction-manager="transactionManager"/>

    <bean class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor" />


    <bean name="serviceDaoImpl" class="it.synclab.fb.jpa.dao.impl.ServiceDaoImpl" />
...

This is the persistence.xml:
<persistence>
    <persistence-unit name="fb-persistence" transaction-type="RESOURCE_LOCAL">  
        <provider>org.hibernate.ejb.HibernatePersistence</provider>
        <mapping-file>META-INF/orm.xml</mapping-file>
        <class>it.entity.Service</class>
        <exclude-unlisted-classes>true</exclude-unlisted-classes>
        <properties>
            <property name="hibernate.dialect" value="org.hibernate.dialect.Oracle10gDialect"/>
            <property name="hibernate.connection.driver_class" value="oracle.jdbc.driver.OracleDriver"/>  
            <property name="hibernate.show_sql" value="true"/>  
            <property name="hibernate.connection.username" value="############"/>  
            <property name="hibernate.connection.password" value="############"/>  
            <property name="hibernate.connection.url" value="jdbc:oracle:thin:@localhost:1521:XE"/> 
        </properties>
   </persistence-unit>
</persistence>
        at oracle.jdbc.driver.DatabaseError.throwBatchUpdateException(DatabaseError.java:629)
        at oracle.jdbc.driver.OraclePreparedStatement.executeBatch(OraclePreparedStatement.java:9467)
        at oracle.jdbc.driver.OracleStatementWrapper.executeBatch(OracleStatementWrapper.java:211)
        at org.hibernate.jdbc.BatchingBatcher.doExecuteBatch(BatchingBatcher.java:70)
        at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:268)
        ... 27 more
    Exception in thread "main" org.springframework.transaction.TransactionSystemException: Could not commit JPA transaction; nested exception is javax.persistence.RollbackException: Transaction marked as rollbackOnly
        at org.springframework.orm.jpa.JpaTransactionManager.doCommit(JpaTransactionManager.java:476)
        at org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:754)
        at org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:723)
        at org.springframework.transaction.interceptor.TransactionAspectSupport.commitTransactionAfterReturning(TransactionAspectSupport.java:393)
        at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:120)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
        at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202)
        at $Proxy34.write(Unknown Source)
        at it.synclab.fb.jpa.test.ConfigTest.insertEnte(ConfigTest.java:47)
        at it.synclab.fb.jpa.test.ConfigTest.main(ConfigTest.java:32)
    Caused by: javax.persistence.RollbackException: Transaction marked as rollbackOnly
        at org.hibernate.ejb.TransactionImpl.commit(TransactionImpl.java:73)
        at org.springframework.orm.jpa.JpaTransactionManager.doCommit(JpaTransactionManager.java:467)
        ... 9 more

为什么一定要复杂？我只是不明白......我希望你们中的一些人有同样的问题并解决了

Answer 1

我不知道我是否正确理解了您的问题，但您的问题可能与ServiceDaoImpl 异常处理有关：

try {
     em.persist(entity);
     em.flush();
} catch(Exception ex) {
     ex.printStackTrace();
}

这是一个非常糟糕的做法（tm）。不要捕获异常，而是让它从您的方法中弹出。这样：

1. 事务分界机制将拦截异常并将事务标记为仅回滚
2. 您不会忽略异常（是的，捕获和记录几乎和吞咽一样糟糕）
3. 很可能会在更高级别捕获异常并正确记录（使用 SLF4J 或类似工具），并且您不会拥有此样板文件。

长话短说：

public class ServiceDaoImpl{

    @PersistenceContext (unitName="fb-persistence")
    private EntityManager em;

    @Transactional(readOnly=false)
    public void write(Service entity){
        em.persist(entity);
        em.flush();
    }

}

请注意，EntityManager 不需要设置器，并且该字段可以是私有的。

Answer 2

在你的 write 方法中添加一个 try catch 块，并在发生错误时抛出异常。

如果您想控制回滚事件，请在您的 @Transactional 注释中为您引发的异常添加 rollbackFor 或 rollbackForClassname 属性。