@Results

package com.flying.entity;

public class Student {
    private Integer stuId;
    private String stuName;
    private Integer stuAge;
    private String stuMajor;
    private Double stuScore;

    public Integer getStuId() { return stuId; }
    public void setStuId(Integer stuId) { this.stuId = stuId; }
    public String getStuName() { return stuName; }
    public void setStuName(String stuName) { this.stuName = stuName; }
    public Integer getStuAge() { return stuAge; }
    public void setStuAge(Integer stuAge) { this.stuAge = stuAge; }
    public String getStuMajor() { return stuMajor; }
    public void setStuMajor(String stuMajor) { this.stuMajor = stuMajor; }
    public Double getStuScore() { return stuScore; }
    public void setStuScore(Double stuScore) { this.stuScore = stuScore; }

    @Override
    public String toString() {
        return "Student{stuId=" + stuId + ", stuName='" + stuName + "', stuAge=" + stuAge +
               ", stuMajor='" + stuMajor + "', stuScore=" + stuScore + "}";
    }
}

package com.flying.mapper;

import com.flying.entity.Student;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.ResultMap;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;
import java.util.List;

public interface StudentMapper {

    /**
     * 查询所有学生，使用 @Results 显式映射下划线列名到驼峰属性
     * 并给该映射命名 id="studentMap"，供其他方法复用
     */
    @Select("SELECT stu_id, stu_name, stu_age, stu_major, stu_score FROM student")
    @Results(id = "studentMap", value = {
            @Result(column = "stu_id", property = "stuId", id = true),
            @Result(column = "stu_name", property = "stuName"),
            @Result(column = "stu_age", property = "stuAge"),
            @Result(column = "stu_major", property = "stuMajor"),
            @Result(column = "stu_score", property = "stuScore")
    })
    List<Student> selectAll();

    /**
     * 根据 ID 查询学生，复用上面定义的 studentMap
     */
    @Select("SELECT stu_id, stu_name, stu_age, stu_major, stu_score FROM student WHERE stu_id = #{id}")
    @ResultMap("studentMap")
    Student selectById(Integer id);
}

package com.flying.test;

import com.flying.entity.Student;
import com.flying.mapper.StudentMapper;
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 java.io.InputStream;
import java.util.List;

public class ResultsTest {
    public static void main(String[] args) throws Exception {
        InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
        SqlSession session = factory.openSession();

        StudentMapper mapper = session.getMapper(StudentMapper.class);

        // 1. 查询所有学生，验证 @Results 映射
        System.out.println("=== 查询所有学生 ===");
        List<Student> all = mapper.selectAll();
        all.forEach(System.out::println);

        // 2. 根据 ID 查询，验证 @ResultMap 复用
        System.out.println("\n=== 根据 ID 查询 ===");
        Student stu = mapper.selectById(1);
        System.out.println(stu);

        session.close();
    }
}