springboot 事务配置 - java报错

@Transactional 放到controller层才有用 Service层就失效~

@RunWith(SpringRunner.class)
@SpringBootTest
public class SpringbootApplicationTests {

	@Autowired
	private UserService userService;

	@Transactional
	@Test
	public void test(){
		userService.insert(new User("D1D22D22","1"));
		userService.insert(new User("AAA111111111111111111111111111111111111111111111111111","1"));
	}

}

这样没问题

@Service
public class UserService {

    @Resource
    public UserMapper userMapper;

    @Transactional
    public void insert(User user) {
         //userMapper.insert(user);

        userMapper.insert(new User("D1D22D22","1"));
        userMapper.insert(new User("AAA111111111111111111111111111111111111111111111111111","1"));
    }
}

 这样就不可以~ 

有人遇到过没？ 再问一下 springboot 可以用 transactionInterceptor  来统一配置事务吗？