文章目录

• 项目场景
• 数据库设计
• POJO
• Dao
• Service
• Test
• 运行结果
• 问题及解决

项目场景

SpringBoot + MyBatis ，实现点餐系统的订单查询。
参考：SpringBoot+MyBatis多表联合查询

数据库设计

通常一个订单中会包含多个菜品，即一条 order 里含多个 item，而且 item 的外键是订单编号 orderid ，连接到订单表 orders。

订单表 orders：

先写一点数据用作测试：

订单菜品表 items：

同样先随便写点数据：

POJO

我个人认为 pojo 中变量的名字最好是和数据库中表里的字段名保持一致，这样之后写映射方便一些，不容易出错。

package com.example.spring.pojo;import java.util.List;public class Order {// 订单ID、桌号private int orderid,tableid;//	顾客ID、消费时间、订单状态private String consumerid,time,status;//	已点菜品列表private List itemList;public int getOrderid() {return orderid;}public void setOrderid(int orderid) {this.orderid = orderid;}public int getTableid() {return tableid;}public void setTableid(int tableid) {this.tableid = tableid;}public String getConsumerid() {return consumerid;}public void setConsumerid(String consumerid) {this.consumerid = consumerid;}public String getTime() {return time;}public void setTime(String time) {this.time = time;}public String getStatus() {return status;}public void setStatus(String status) {this.status = status;}public List getItemList() {return itemList;}public void setItemList(List itemList) {this.itemList = itemList;}
}

package com.example.spring.pojo;public class Item {//	订单列表private int orderid;//	菜名、菜品份量、图片private String name,size,img;//	单价、数量private int price,num;public int getOrderid() {return orderid;}public void setOrderid(int orderid) {this.orderid = orderid;}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getSize() {return size;}public void setSize(String size) {this.size = size;}public String getImg() {return img;}public void setImg(String img) {this.img = img;}public int getPrice() {return price;}public void setPrice(int price) {this.price = price;}public int getNum() {return num;}public void setNum(int num) {this.num = num;}
}

Dao

package com.example.spring.dao;import com.example.spring.pojo.Order;
import org.apache.ibatis.annotations.Mapper;@Mapper
public interface OrderDao {/*** 一对多联合查询* */Order findByOrderid(int orderid);}

多表查询的映射需要自定义一下结果对象 resultMap：

select a.orderid,a.tableid,a.consumerid,a.time,a.status,b.orderid,b.name,b.size,b.img,b.price,b.num from orders a,items b where a.orderid=b.orderid and a.orderid=#{orderid}

Service

package com.example.spring.service;import com.example.spring.pojo.Order;import java.util.List;public interface OrderService {/*** 根据订单编号查询订单* */public Order findByOrderid(int orderid);}

package com.example.spring.service.impl;import com.example.spring.pojo.Order;
import com.example.spring.dao.OrderDao;
import com.example.spring.service.OrderService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;@Service
public class OrderServiceImpl implements OrderService {@Autowiredprivate OrderDao orderDao;/*** 一对多联合查询* */public Order findByOrderid(int orderid){return orderDao.findByOrderid(orderid);}
}

Test

做个单元测试看看能不能正确访问数据并取出：

package com.example.spring.service.impl;import com.example.spring.pojo.Item;
import com.example.spring.pojo.Order;
import org.junit.jupiter.api.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.test.context.testng.AbstractTestNGSpringContextTests;import java.util.List;@SpringBootTest
@RunWith(SpringJUnit4ClassRunner.class)
class OrderServiceImplTest extends AbstractTestNGSpringContextTests {@AutowiredOrderServiceImpl orderService;@Testpublic void findByOrderid() {Order order = orderService.findByOrderid(10001);System.out.println("订单编号:" + order.getOrderid());System.out.println("桌号:" + order.getTableid());System.out.println("时间:" + order.getTime());List itemList = order.getItemList();for(int i=0;iSystem.out.println(itemList.get(i).getName() + "\t" + itemList.get(i).getSize() + "\t" + itemList.get(i).getNum() + "\t" + itemList.get(i).getPrice());}}
}

运行结果

问题及解决

• Cannot resolve symbol “RunWith”.
  添加依赖。

		org.junit.jupiterjunit-jupiter-api5.8.2testorg.junit.platformjunit-platform-launcher1.1.0testjunitjunit

参考：springboot 单元测试service遇到的坑（cannot resolve symbol “RunWith” ）