如何仅在 spring-transactions 交易成功时才发送电子邮件

Question

我想在数据库中创建一个用户，并使用 AWS SES 向此案例的用户发送电子邮件。

1. 如果用户在数据库中提交事务成功=>发送电子邮件
2. 如果发送电子邮件 AWS SES 失败（检查异常）=> 回滚数据库中的用户创建
3. 如果用户在数据库中提交事务失败 => 不要使用 AWS 向用户发送电子邮件

我的代码存在问题：如果我的sendEmail方法抛出异常，则会提交事务。

配置：带有 spring-data-jpa 的 Spring-Boot 项目

class EmailServiceImpl {   

    @Transactional(rollbackFor = Exception.class)
    @Override
    public User createUserAndSendEmail(UserDto userDto) throws UserEmailException {
        try {
            //rollback userCreation if sendEmail throw a checkedException
            User user = userService.create(userDto);
            sendEmail(user);
            return user;

        } catch (Exception exception) {
            throw new UserEmailException(exception.getMessage());
        }
    }

    //don't send email if userCommit in database failed
    private void sendEmail(User user) {
        amazonEmailService.sendMail(user);
    }
}

class UserServiceImpl {    

   @Transactional(propagation = Propagation.REQUIRES_NEW)
   @Override
   public User create(UserDto userDto) throws Exception {
       User user = mapp(userDto);
       return userRepository.save(user);
   }
}

Answer 1

要在 TX commit 后执行某些操作，您可以使用@TransactionalEventListenerwith TransactionPhase.AFTER_COMMIT（默认设置）。将您想要执行的操作放入TransactionalEventListener：

使用ApplicationEventPublisher来发布UserCreatedEvent：

public class EmailServiceImpl {   

    @Autowired
    private ApplicationEventPublisher applicationEventPublisher;

    @Transactional(rollbackFor = Exception.class)
    public User createUserAndSendEmail(UserDto userDto) throws UserEmailException {
        try {
            User user = userService.create(userDto);

            //Publish UserCreatedEvent such the UserCreatedEventHandler can handled it after TX commit
            applicationContext.publishEvent(new UserCreatedEvent(user));

            return user;
        } catch (Exception exception) {
            throw new UserEmailException(exception.getMessage());
        }
    }
}

并且UserCreatedEvent将在 TX 提交后由该处理程序处理：

@Component
public class UserCreatedEventHandler {

    @TransactionalEventListener(phase = TransactionPhase.AFTER_COMMIT)
    public void handle(UserCreatedEvent event) {    
        try{
            amazonEmailService.sendMail(user);
            System.out.println("Good, can send email.");
        }catch(Exception exception){
            System.out.println("Sad, fail to send email , so remove user from DB...");
            userService.remove();
        }
    }
}

Deinum 的好接球。如果你使用我的建议，你必须更改userService.create()为@Transactional(propagation = Propagation.REQUIRES)