<dependency>
      <groupId>org.mybatis.spring.boot</groupId>
      <artifactId>mybatis-spring-boot-starter</artifactId>
      <version>2.1.1</version>
</dependency>

@Mapper
@Repository
public interface IUserDao {

    User getUserById(int id);

    List<User> getAllUsers();

    void updateUser(User user);

    void deleteUser(int id);

    void addUser(User user);
}

<?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.tony.dao.IUserDao">
    <select id="getUserById" parameterType="int" resultType="com.tony.entities.User">
        select * from test.mvctest20200229
        where id=#{id}
    </select>
    <select id="getAllUsers" resultType="com.tony.entities.User">
        select * from test.mvctest20200229;
    </select>

    <update id="updateUser" parameterType="com.tony.entities.User">
        update test.mvctest20200229 set
        add_time=#{add_time},
        name=#{name},
        age=#{age},
        remark=#{remark}
    </update>

    <delete id="deleteUser" parameterType="int">
        delete from test.mvctest20200229
        where id=#{id}
    </delete>

    <insert id="addUser" parameterType="com.tony.entities.User">
        insert into test.mvctest20200229(name,age,remark) values
        (#{name},#{age},#{remark})
    </insert>
</mapper>

mybatis.mapper-locations=classpath:mapping/IUserDao.xml
spring.datasource.url=jdbc:mysql://localhost:3306/test
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.username=root
spring.datasource.password=123456