java工作中的DTO VO Query DO别再用Map接收了

以项目的方式展示DTO VO Query DO的使用
1.先看项目结构

dao接口定义

public interface OrderDao  {
    Order get(Long id) throws Exception;

    int create(Order order) throws Exception;

    int update(Order order) throws Exception;

    int delete(Long id) throws Exception;
}

public interface UserDao {
    /**
     * 根据用户查询用户订单信息
     * @param userQuery
     * @return
     */
    List selectUserOrderByUser(UserQuery userQuery);

    User get(Long id) throws Exception;

    int create(User user) throws Exception;

    int update(User user) throws Exception;

    int delete(Long id) throws Exception;
}

 xml文件

 
    
    select
        user.id as uid,
        user.userName as userName.
        order.oid as oid,
        order.code as code,
        order.createTime as createTime

     from user left join order where user.id=order.uid and user.id=#{id} or user.userName=#{userName}
    

service

@Service
public class UserServiceImpl implements UserService {
    @Autowired
    private UserDao userDao;

    @Autowired
    private GoodsService goodsService;


    @Override
    public UserOrderVO selectUserOrderByUser(UserQuery userQuery) {
        UserOrderVO userOrderVO = new UserOrderVO();
        UserOrderDTO userOrderDTO = userDao.selectUserOrderByUser(userQuery);
        if(userOrderDTO == null) return null;
        BeanUtils.copyProperties(userOrderDTO,userOrderVO);
        //service调用service把结果封装到同一个vo中
        List orderGoodsDTOList = userOrderVO.getOrderGoodsDTOList();
        for (OrderGoodsDTO orderGoodsDTO : orderGoodsDTOList) {
            //订单id查询出商品
            List goodsList = goodsService.selectGoodsByOrderId(orderGoodsDTO.getOid());
            orderGoodsDTO.setGoodsList(goodsList);
        }
        //订单条数
        userOrderVO.setOrderCount(orderGoodsDTOList.size());
        float totalPrice=0;
        //计算该用户的商品总价
        for (OrderGoodsDTO orderGoodsDTO : userOrderVO.getOrderGoodsDTOList()) {
            List goodsList = orderGoodsDTO.getGoodsList();
            for (Goods goods : goodsList) {
                totalPrice+=goods.getPrice();
            }
        }
        userOrderVO.setTotalPrice(totalPrice);
        return userOrderVO;
    }

}

Controller

@RestController
@RequestMapping("/userOrder")
public class UserOrderController {
    @Autowired
    private UserService userService;

      @RequestMapping("/selectUserOrderByUser")
    public JsonResult selectUserOrderByUser(@Validated UserQuery userQuery, BindingResult bindingResult){
        JsonResult jsonResult=new JsonResult();
        if(bindingResult.hasErrors()){
            String defaultMessage = bindingResult.getFieldError().getDefaultMessage();
            jsonResult.setCode(500);
            jsonResult.setMsg(defaultMessage);
            return jsonResult;
        }
        UserOrderVO userOrderVO = userService.selectUserOrderByUser(userQuery);
        jsonResult.setData(userOrderVO);
        if(userOrderVO == null){
            jsonResult.setCode(500);
            jsonResult.setMsg("未查找数据");
        }
        return jsonResult;
    }
}

 JsonResult 工具类

public class JsonResult {

    private int code;

    private String msg;

    private Object data;

    private Date timestamp;

    public JsonResult() {
        this.code = 200;
        this.msg = " *** 作成功";
        this.data = null;
        this.timestamp = new Date();
    }
    public JsonResult(Object data){
        this();
        this.data=data;
    }
}

1.Query负责接收前端的参数

public class UserQuery {
   @NotNull(message = "id不能为空！")
    private Integer id;
    @NotEmpty(message = "userName不能为空！")
    private String userName;
}

2.DO与数据库的字段保持一致和数据库交互

public class Goods {
    private int gid;
    private int oid;
    private String productName;
    private float price;

}

public class Order {
    private Integer oid;
    private Integer uid;
    private String code;
    private Date creatTime;
}

public class User {
    private Integer uid;
    private String username;
}

3.DTO dao层和service层和返回的数据都可以用dto,通常数据表查询都是多表查询把多张表的查询结果封装在一个dto中即可

public class UserOrderDTO {
    private Integer uid;
    private String userName;
    private List orderGoodsDTOList;
}

public class OrderGoodsDTO {
    private Integer oid;
    private String code;
    private Date createTime;
    private List goodsList;
}

4.VO负责返回前端的数据 在service层返回即可

public class UserOrderVO {
    private Integer uid;
    private String userName;
    private List orderGoodsDTOList;
    private int orderCount;
    private float totalPrice;
}

漏传参数调用接口打印

http://localhost:8080/userOrder/selectUserOrderByUser?id= 打印 

{"code":500,"msg":"id不能为空！","data":null,"timestamp":1652357412150}

正常调用接口打印http://localhost:8080/userOrder/selectUserOrderByUser?id=7788 &userName=不爱穿裤子的小红娘

{
	"code": 200,
	"msg": " *** 作成功",
	"data": {
		"uid": 7788,
		"userName": "不爱穿裤子的小红娘",
		"orderGoodsDTOList": [{
			"oid": 1,
			"code": "1559722872969097255",
			"createTime": 1652338841593,
			"goodsList": [{
				"gid": 1,
				"productName": "冬瓜",
				"price": 5.8
			}, {
				"gid": 2,
				"productName": "西瓜",
				"price": 4.5
			}, {
				"gid": 3,
				"productName": "哈密瓜",
				"price": 3.0
			}]
		}, {
			"oid": 2,
			"code": "2606159379158097255",
			"createTime": 1652338841593,
			"goodsList": [{
				"gid": 4,
				"productName": "苹果5s",
				"price": 500.0
			}, {
				"gid": 5,
				"productName": "小米8Puls",
				"price": 888.0
			}, {
				"gid": 6,
				"productName": "华为荣耀30P",
				"price": 1888.0
			}]
		}],
		"orderCount": 2,
		"totalPrice": 3289.3
	},
	"timestamp": 1652338841593
}