JAVA

【MyBatis】映射案例的最佳解决方案

结构图

数据库脚本：本地下载

案例

1.创建实体类

Goods.java

package com.bean;

import java.io.Serializable;

public class Goods implements Serializable{

    /**
     *
     */
    private static final long serialVersionUID = 4049728674182319106L;
    private Integer goodsId;
    private String goodsName;
    private Double goodsPrice;
    private Integer goodsNum;
    private GoodsType goodsType;

    public Goods() {
    }

    public Goods(Integer goodsId, String goodsName, Double goodsPrice,
                 Integer goodsNum, GoodsType goodsType) {
        super();
        this.goodsId = goodsId;
        this.goodsName = goodsName;
        this.goodsPrice = goodsPrice;
        this.goodsNum = goodsNum;
        this.goodsType = goodsType;
    }

    public Integer getGoodsId() {
        return goodsId;
    }

    public void setGoodsId(Integer goodsId) {
        this.goodsId = goodsId;
    }

    public String getGoodsName() {
        return goodsName;
    }

    public void setGoodsName(String goodsName) {
        this.goodsName = goodsName;
    }

    public Double getGoodsPrice() {
        return goodsPrice;
    }

    public void setGoodsPrice(Double goodsPrice) {
        this.goodsPrice = goodsPrice;
    }

    public Integer getGoodsNum() {
        return goodsNum;
    }

    public void setGoodsNum(Integer goodsNum) {
        this.goodsNum = goodsNum;
    }

    public GoodsType getGoodsType() {
        return goodsType;
    }

    public void setGoodsType(GoodsType goodsType) {
        this.goodsType = goodsType;
    }

    @Override
    public String toString() {
        return "Goods [goodsId=" + goodsId + ", goodsName=" + goodsName
                + ", goodsPrice=" + goodsPrice + ", goodsNum=" + goodsNum
                + ", goodsType=" + goodsType + "]";
    }
}

GoodsType.java

package com.bean;

import java.util.List;

public class GoodsType {
    private Integer typeId;
    private String typeName;
    private List<Goods> goodsList;

    public GoodsType() {
    }

    public GoodsType(Integer typeId, String typeName, List<Goods> goodsList) {
        super();
        this.typeId = typeId;
        this.typeName = typeName;
        this.goodsList = goodsList;
    }

    public Integer getTypeId() {
        return typeId;
    }

    public void setTypeId(Integer typeId) {
        this.typeId = typeId;
    }

    public String getTypeName() {
        return typeName;
    }

    public void setTypeName(String typeName) {
        this.typeName = typeName;
    }

    public List<Goods> getGoodsList() {
        return goodsList;
    }

    public void setGoodsList(List<Goods> goodsList) {
        this.goodsList = goodsList;
    }

    @Override
    public String toString() {
        return "GoodsType [typeId=" + typeId + ", typeName=" + typeName
                + ", goodsList=" + goodsList + "]";
    }
}

2.编写Mapper接口

GoodsMapper.java

package com.mapper;

import java.util.List;

import com.bean.Goods;

public interface GoodsMapper {
    public List<Goods> findAll();
    /**
     * 给关联关系对象(商品类型)提供查找其下商品的方法
     * 如果要查某个商品类型信息的时候要带出相关的商品信息
     * @param typeId 某个商品类型的ID
     * @return 返回某个商品类型下的商品集
     */
    public List<Goods> findByType(int typeId);
}

GoodsTypeMapper.java

package com.mapper;

import java.util.List;

import com.bean.GoodsType;

public interface GoodsTypeMapper {
    public List<GoodsType> findAll();
    public GoodsType findById(int typeId);
}

3.编写XML文件

GoodsMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.mapper.GoodsMapper">
<select id="findAll" resultMap="BaseResultMap">
select * from goods
left join goods_type
on goods_type.typeId = goods.goods_type
</select>
<select id="findByType" parameterType="java.lang.Integer" resultMap="BaseResultMap">
select * from goods
left join goods_type
on goods_type.typeId = goods.goods_type
where goods_type = #{id}
</select>
<resultMap type="com.bean.Goods" id="BaseResultMap">
<id column="goods_id" property="goodsId" jdbcType="INTEGER" />
<result column="goods_name" property="goodsName" jdbcType="VARCHAR" />
<result column="goods_price" property="goodsPrice" jdbcType="DOUBLE" />
<result column="goods_num" property="goodsNum" jdbcType="INTEGER" />
<association property="goodsType" javaType="com.bean.GoodsType" resultMap="com.mapper.GoodsTypeMapper.BaseResultMap" />
</resultMap>
</mapper>

GoodsTypeMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.mapper.GoodsTypeMapper">
<select id="findAll" resultMap="BaseResultMap">
select * from goods_type
</select>
<select id="findById" parameterType="java.lang.Integer" resultMap="BaseResultMap">
select * from goods_type
where typeId = #{id}
</select>
<resultMap type="com.bean.GoodsType" id="BaseResultMap">
<id property="typeId" column="typeId" javaType="java.lang.Integer" />
<result column="typeName" property="typeName" jdbcType="VARCHAR" />
</resultMap>
</mapper>

mybatis.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC" />
<dataSource type="POOLED">
<property name="driver" value="com.mysql.jdbc.Driver" />
<property name="url" value="jdbc:mysql://127.0.0.1:3306/spring?useUnicode=true&amp;characterEncoding=utf8" />
<property name="username" value="root" />
<property name="password" value="123456" />
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="com/mapper/GoodsMapper.xml" />
<mapper resource="com/mapper/GoodsTypeMapper.xml" />
</mappers>
</configuration>

4.编写service层

GoodsTypeService.java

package com.service;

import java.io.Reader;
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 com.bean.Goods;
import com.bean.GoodsType;
import com.mapper.GoodsMapper;
import com.mapper.GoodsTypeMapper;

public class GoodsTypeService {
    public GoodsType findById(int typeId){
        SqlSession sqlSession = null;
        try{
            String resource = "mybatis.xml";
            Reader reader = Resources.getResourceAsReader(resource);
            SqlSessionFactory ssf = new SqlSessionFactoryBuilder().build(reader);
            sqlSession = ssf.openSession();
            GoodsTypeMapper goodsTypeMapper = sqlSession.getMapper(GoodsTypeMapper.class);
            GoodsType goodsType = goodsTypeMapper.findById(typeId);
            GoodsMapper goodsMapper = sqlSession.getMapper(GoodsMapper.class);
            List<Goods> goodsList = goodsMapper.findByType(typeId);
// 组装
            goodsType.setGoodsList(goodsList);
            return goodsType;
        }catch(Exception e){
            e.printStackTrace();
            throw new RuntimeException(e);
        }finally{
            sqlSession.close();
        }
    }
}

teat.java

package com.test;

import org.junit.Before;
import org.junit.Test;

import com.bean.GoodsType;
import com.service.GoodsTypeService;

public class test {

    public void test01() {
        GoodsTypeService goodsTypeService = new GoodsTypeService();
        GoodsType goodsType = goodsTypeService.findById(1);
        System.out.println(goodsType);
    }

    @Test
    public void testF(){
        test01();
    }

    @Before
    public void before() {

    }
}

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MyBatis

【MyBatis】映射案例的最佳解决方案

https://www.benzhu.xyz/archives/mybatis008

作者

小猪

发布于

2019-04-02

更新于

2024-11-24

许可协议

CC BY 4.0

【MyBatis】映射案例的最佳解决方案

结构图

案例

1.创建实体类

2.编写Mapper接口

3.编写XML文件

4.编写service层

作者

发布于

更新于

许可协议

评论