如何从服务类回滚事务？

Question

我试图通过抛出异常来回滚某些条件。但我找不到正确的方法来做到这一点。这是我的服务类

@Service
public class UserManager implements IUserManager {

    private final IBasicEM basicEM;

    public ApplicantInfoManager(IBasicEM basicEM) {
        this.basicEM = basicEM;
    }

    @Override
    @TransactionAttribute(TransactionAttributeType.REQUIRES_NEW)
    public boolean purgeUser(Long id) throws Exception {
      //business logic
      basicEM.Update(entity)
      if(//condition) {
          throw New RollBackException("//message")
      }
      //business logic
    }
}

这是我的BasicEM 课程

@Component
@Transactional(value = "transactionManager", rollbackFor = Exception.class)
public class BasicEM {
    @PersistenceContext(unitName = "db1")
    private EntityManager em;

    public void update(Object target) {
        em.merge(target);
    }
}

所以我想要调用 update 方法，然后如果条件为真，则撤消更新。 我的意图是当我抛出异常时，事务结束并且不提交更新。但我错了，更新已经完成。请帮助我实现我的目标。

Answer 1

为了实现你想要的，你需要在 Service 方法中已经有一个事务。 @Transactional(value = "transactionManager", rollbackFor = Exception.class) 的默认传播类型为 Propagation.REQUIRED，这意味着如果您的 Service 已包含在事务中，则 basicEM.Update(entity) 也将包含在此类事务中。

@Service
public class UserManager implements IUserManager {

    private final IBasicEM basicEM;

    public ApplicantInfoManager(IBasicEM basicEM) {
        this.basicEM = basicEM;
    }

    @Override
    @Transactional(value = "transactionManager", 
       propagation = Propagation.REQUIRES_NEW, rollbackFor = RollBackException.class)
    public boolean purgeUser(Long id) throws Exception {
      //business logic
      basicEM.Update(entity)
      if(//condition) {
          throw New RollBackException("//message")
      }
      //business logic
    }
}

如果RollBackException 是RuntimeException，则无需显式配置事务在抛出时应回滚。如果不是，则需要配置如下：@Transactional(value = "transactionManager", propagation = Propagation.REQUIRES_NEW, rollbackFor = RollBackException.class)。