Resultmap result map

Time:2022-5-6

Expand an object to save the query results

Create a dto package SRC main Java com mybatis dto

Dto is a special JavaBean,JavaBean is a kind of Java class, which conforms to a certain writing specification. It is a specification of entity and information.

JavaBean specification:

(1) There must be 1 Public parameterless construct

(2) All properties private

(3) Attributes are exposed to other programs through getters and setters

(4) Class requires serializability

Create goodsdto in dto directory

 

package com.MyBatis.dto;

import com.MyBatis.entity.Goods;

public class GoodsDTO {
    private Goods goods;
    private String categoryName;
    private String test;

    public Goods getGoods() {
        return goods;
    }
    public void setGoods(Goods goods) {
        this.goods = goods;
    }
    public String getCategoryName() {
        return categoryName;
    }
    public void setCategoryName(String categoryName) {
        this.categoryName = categoryName;
    }
    public String getTest() {
        return test;
    }
    public void setTest(String test) {
        this.test = test;
    }
}

 

Write in mapper XMLLabel and write SQL statements

select g.*,c.category_name,'1' as test from t_goods g,t_category c
        where g.category_id = c.category_id

test

@Test
    public void testSelectGoodsDTO(){
        SqlSession sqlSession=null;
        try{
            sqlSession=MyBatisUtils.openSession();
            List list = sqlSession.selectList("goods.selectGoodsDTO");
            for(GoodsDTO g : list){
                System.out.println(g.getGoods().getTitle());
            }
        }catch (Exception e){
            throw e;
        }finally {
            MyBatisUtils.closeSession(sqlSession);
        }
    }

 

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