MyBatis一对一查询使用ResultType映射

绝地灬酷狼 2022-06-15 05:58 181阅读 0赞

####    需求背景：查询订单信息关联用户信息。 ####

## mapper.xml ##

<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
    <mapper namespace="com.hl.mybatis.first.mapper.OrdersCustomMapper">
        
        <select id="findOrdersUser" resultType="com.hl.myabtis.first.beas.OrdersCustom">
            select orders.*,user.username,user.sex,user.address from orders,user where orders.user_id = user.id
        </select>   
    </mapper>

## mapepr.java ##

package com.hl.mybatis.first.mapper;
    
    import java.util.List;
    
    import com.hl.myabtis.first.beas.OrdersCustom;
    
    
    public interface OrdersCustomMapper {
        //查询订单关联用户信息
        public List<OrdersCustom> findOrdersUser() throws Exception;
    }

## 原始订单类： ##

package com.hl.myabtis.first.beas;
    
    import java.util.Date;
    
    public class Orders { 
    
        private Integer id;
    
        private Integer user_id;
    
        private String number;
    
        private Date createtime;
    
        private String note;
    
        public Integer getId() {
            return id;
        }
    
        public void setId(Integer id) {
            this.id = id;
        }
    
        public Integer getUserId() {
            return user_id;
        }
    
        public void setUserId(Integer userId) {
            this.user_id = userId;
        }
    
        public String getNumber() {
            return number;
        }
    
        public void setNumber(String number) {
            this.number = number;
        }
    
        public Date getCreatetime() {
            return createtime;
        }
    
        public void setCreatetime(Date createtime) {
            this.createtime = createtime;
        }
    
        public String getNote() {
            return note;
        }
    
        public void setNote(String note) {
            this.note = note;
        }
    
        @Override
        public String toString() {
            return "Orders [id=" + id + ", userId=" + user_id + ", number=" + number
                    + ", createtime=" + createtime + ", note=" + note + "]";
        }
    
    }

## 拓展订单类： ##

package com.hl.myabtis.first.beas;
    /** * 扩展订餐类， * @author 浪丶荡 * */
    public class OrdersCustom extends Orders { 
    
        //通过此类可以映射订单和用户的查询结果
    
        //添加用户属性
        private String username;
    
        private String sex;
    
        private String address;
        public String getUsername() {
            return username;
        }
    
        public void setUsername(String username) {
            this.username = username;
        }
    
        public String getSex() {
            return sex;
        }
    
        public void setSex(String sex) {
            this.sex = sex;
        }
    
        public String getAddress() {
            return address;
        }
    
        public void setAddress(String address) {
            this.address = address;
        }
    
        @Override
        public String toString() {
            return super.toString()+"-----"+"OrdersCustom [username=" + username + ", sex=" + sex
                    + ", address=" + address + "]";
        }
    
    
    }

## 测试代码： ##

package com.hl.mybatis.first.test;
    
    import java.io.InputStream;
    import java.util.List;
    
    import org.apache.ibatis.io.Resources;
    import org.apache.ibatis.session.SqlSession;
    import org.apache.ibatis.session.SqlSessionFactory;
    import org.apache.ibatis.session.SqlSessionFactoryBuilder;
    import org.junit.Before;
    import org.junit.Test;
    
    import com.hl.myabtis.first.beas.OrdersCustom;
    import com.hl.mybatis.first.mapper.OrdersCustomMapper;
    
    public class OrdersMapperTest {
    
        private SqlSessionFactory sqlSessionFactory;
    
        @Before
        public void testBefore() throws Exception{
    
            String resource = "SqlMapConfig.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource );
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        }
        @Test
        public void testFindOrdersUser() throws Exception{
            SqlSession sqlSession = sqlSessionFactory.openSession();
            OrdersCustomMapper ordersMapper = sqlSession.getMapper(OrdersCustomMapper.class);
            List<OrdersCustom> list = ordersMapper.findOrdersUser();
            for (OrdersCustom ordersCustom : list) {
                System.out.println(ordersCustom);
            }
        }
    }