jdbc-template.java

public abstract class BaseDAO {
  private static final Logger L = LoggerFactory.getLogger(BaseDAO.class);

  @Autowired
  protected JdbcTemplate template;

  @PostConstruct
  public void afterInit() {
    L.info("base dao");
    if (template == null) {
      L.warn("got null jdbc template");
    } else {
      L.info("got jdbc template {}", template.getDataSource().toString());
    }
  }
}

@Component
public class UserDAO extends BaseDAO {
  private static final Logger L = LoggerFactory.getLogger(UserDAO.class);

  public void test() {
    Map data = template.queryForMap("select * from account limit 1");
    for (Object o : data.entrySet()) {
      Map.Entry entry = (Map.Entry) o;
      L.info("got entry {} > {}", entry.getKey(), entry.getValue());
    }
  }
}


@Service
public class UserService implements IUserService {
  @Autowired
  private UserDAO userDAO;
  
  @PostConstruct
  public void test() {
    userDAO.test();
  }
}