事务的注解

@Transactional
在处理dao层或service层的事务操作时，譬如删除失败时的回滚操作。使用@Transactional 作为注解，但是需要在配置文件激活。

<!-- 开启注解方式声明事务 -->
    <tx:annotation-driven transaction-manager="transactionManager" />

@Service
public class CompanyServiceImpl implements CompanyService {
  @Autowired
  private CompanyDAO companyDAO;
  @Transactional(propagation = Propagation.REQUIRED, readOnly = false, rollbackFor = Exception.class)
  public int deleteByName(String name) {
    int result = companyDAO.deleteByName(name);
    return result;
  }
  ...
}