1、pom.xml中引入依赖【注意根据自己的spring boot版本选择对应的mysql和mybatis版本】

		<dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId></dependency><dependency><groupId>org.mybatis.spring.boot</groupId><artifactId>mybatis-spring-boot-starter</artifactId><version>2.1.0</version></dependency>

2、resources/application.xml配置

spring:datasource:driver-class-name: com.mysql.cj.jdbc.Driverusername: rootpassword:url: jdbc:mysql://127.0.0.1:3306/mall?characterEncoding=utf-8&useSSL=false
mybatis:configuration:map-underscore-to-camel-case: truemapper-locations: classpath:mappers/*.xml

3、pojo/Category

@Data
public class Category {private Integer id;private Integer parentId;private String name;private Boolean status;private Integer sortOrder;private Date createTime;private Date updateTime;
}

4、dao/CategoryMapper.java

@Mapper
public interface CategoryMapper {Category queryById(Integer id);
}

5、建立同名xml文件

resources/mappers/CategoryMapper.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.imooc.mall.dao.CategoryMapper"><sql id="Base_Column_List">id, parent_id, name, status, sort_order, create_time, update_time</sql><select id="queryById" resultType="com.imooc.mall.pojo.Category">select<include refid="Base_Column_List"></include>from mall_categorywhere id = #{id}</select>
</mapper>

注意点：

        namespace对应mapper.java地址

        id对应的是mapper中的方法

        resultType对应的是pojo

        Base_Column_List是公共字段提取

6、application.java注入

@SpringBootApplication
@MapperScan(basePackages = "com.imooc.mall.dao")
public class MallApplication {public static void main(String[] args) {SpringApplication.run(MallApplication.class, args);}}

7、使用

package com.imooc.mall;import com.imooc.mall.dao.CategoryMapper;
import com.imooc.mall.pojo.Category;
import org.junit.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.SpringRunner;@RunWith(SpringRunner.class)
@SpringBootTest
public class MallApplicationTests {@Autowiredprivate CategoryMapper categoryMapper;@Testpublic void contextLoads() {}@Testpublic void queryByIdTest() {Category category = categoryMapper.queryById(100001);System.out.println(category.toString());}}