添加依赖

mysql；数据源druid；mybatis

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.21</version>
</dependency>
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid-spring-boot-starter</artifactId>
    <version>1.2.11</version>
</dependency>
<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>2.2.2</version>
</dependency>

配置文件 application.properties

mybatis.mapper-locations=classpath:mapper/*.xml
mybatis.type-aliases-package=net.img.entity
#mybatis.type-handlers-package=com.example.typehandler
mybatis.configuration.map-underscore-to-camel-case=true
mybatis.configuration.default-fetch-size=100
mybatis.configuration.default-statement-timeout=30
mybatis.executor-type=REUSE

配置文件 application-dev.properties

配置开发环境的数据库账号密码

spring.datasource.druid.url=jdbc:mysql://localhost/blog
spring.datasource.druid.username=begincode
spring.datasource.druid.password=begincode123
#spring.datasource.druid.driver-class-name= #或 spring.datasource.driver-class-name=
spring.datasource.type=com.alibaba.druid.pool.DruidDataSource

配置文件 application-prod.properties

线上自己复制一份即可

创建mapper.xml文件

<?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="net.img.mapper.SysUserMapper">
        <!-- 通用查询映射结果 -->
        <resultMap id="BaseResultMap" type="net.img.entity.SysUserEntity">
                    <result column="id" property="id"/>
                    <result column="user_id" property="userId"/>
                    <result column="password" property="password"/>
                    <result column="nick_name" property="nickName"/>
                    <result column="email" property="email"/>
                    <result column="gender" property="gender"/>
                    <result column="uuid" property="uuid"/>
                    <result column="avatar" property="avatar"/>
                    <result column="remark" property="remark"/>
                    <result column="user_status" property="userStatus"/>
                    <result column="create_time" property="createTime"/>
                    <result column="update_time" property="updateTime"/>
        </resultMap>

        <!-- 通用查询结果列 -->
        <sql id="Base_Column_List">
                id, user_id, password, nick_name, email, gender, uuid, avatar, remark, user_status, create_time, update_time
        </sql>

    <select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="Long">
        select
        <include refid="Base_Column_List"/>
        from sys_user
        where user_id = #{userId}
    </select>

</mapper>

mapper接口

package net.img.mapper;

import net.img.entity.SysUserEntity;

/**
 * <p>
 * 系统用户 Mapper 接口
 * @since 2023-10-11
 */

public interface SysUserMapper {
        /**
         * 根据主键查询系统用户
         */
        SysUserEntity selectByPrimaryKey(Long userId);
}

用户实体，忽略了get set 方法

package net.img.entity;

import java.io.Serializable;
import java.util.Date;

/**
 * 系统用户
 * @since 2023-10-11
 */
public class SysUserEntity implements Serializable {
    private static final long serialVersionUID = 1L;
    private Long id;
    private Long userId;
    private String password;
    private String nickName;
    private String email;
    private Byte gender;
    private String uuid;
    private String avatar;
    private String remark;
    private String userStatus;
    private Date createTime;
    private Date updateTime;
 
}

启动文件增加mapper扫描

@MapperScan(value="net.img.mapper")

红框为新增mapper扫描路径

写个controller，获取用户信息

@Controller
public class HelloController {

    @Resource
    private SysUserMapper sysUserMapper;

    @ResponseBody
    @RequestMapping("/getUser")
    public SysUserEntity getUser(Long userId) {
        return sysUserMapper.selectByPrimaryKey(userId);
    }
}

启动吧朋友们

启动后访问url 获取用户信息