マッパー定義例

Item.java

package com.github.apz.sample.repository;

import lombok.Getter;
import lombok.NoArgsConstructor;

import java.time.LocalDateTime;

@NoArgsConstructor @Getter
public class Item {
    private Long id;
    private String name;
    private LocalDateTime registerDateTime;
}

ItemMapper.java

package com.github.apz.sample.mapper;

import com.github.apz.sample.repository.Item;
import org.apache.ibatis.annotations.Mapper;

import java.util.List;

@Mapper
public interface ItemMapper {
    List<Item> selectItem(String id);
}

ItemMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "https://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.github.apz.sample.mapper.ItemMapper">
    <select id="selectItem" resultMap="Item">
        SELECT
            id
            , name
            , register_time
        FROM
            item
        <where>
            <if test="id != null">
                id = #{id}
            </if>
        </where>
    </select>

    <resultMap id="Item" type="com.github.apz.sample.repository.Item">
        <id column="id" property="id"/>
        <id column="name" property="name"/>
        <id column="register_time" property="registerDateTime"/>
    </resultMap>
</mapper>