package org.example.entity;

public class Emp {

    private Integer empId;

    private String empName;

    private Integer age;

    private String gender;

    private Integer deptId;

    public Emp() {

    }

    public Emp(Integer empId, String empName, Integer age, String gender, Integer deptId) {

        this.empId = empId;

        this.empName = empName;

        this.age = age;

        this.gender = gender;

        this.deptId = deptId;

    }

    public Integer getEmpId() {

        return empId;

    }

    public void setEmpId(Integer empId) {

        this.empId = empId;

    }

    public String getEmpName() {

        return empName;

    }

    public void setEmpName(String empName) {

        this.empName = empName;

    }

    public Integer getAge() {

        return age;

    }

    public void setAge(Integer age) {

        this.age = age;

    }

    public String getGender() {

        return gender;

    }

    public void setGender(String gender) {

        this.gender = gender;

    }

    public Integer getDeptId() {

        return deptId;

    }

    public void setDeptId(Integer deptId) {

        this.deptId = deptId;

    }

    @Override

    public String toString() {

        return "Emp{" +

                "empId=" + empId +

                ", empName='" + empName + '\'' +

                ", age=" + age +

                ", gender='" + gender + '\'' +

                ", deptId=" + deptId +

                '}';

    }

}

public interface EmpMapper {

   public Emp queryEmpById(@Param("id") int id);

}

<?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="org.example.mapper.EmpMapper">

    <!--

        resultMap：设置自定义映射关系

        id：唯一标识

        type：处理映射关系的实体类的类型

        常用的标签：

        id：处理主键和实体类中属性的映射关系

        result：处理普通字段实体类中属性的映射关系

        column：设置映射关系中的字段名，必须是sql查询出的某个字段

        property：设置映射关系中的属性的属性名，必须是处理的实体类类型中的属性名

    -->

    <resultMap id="empResultMap" type="emp">

        <id column="emp_id" property="empId"></id>

        <result column="emp_name" property="empName"></result>

        <result column="age" property="age"></result>

        <result column="gender" property="gender"></result>

        <result column="dept_id" property="deptId"></result>

    </resultMap>

    <select id="queryEmpById" resultMap="empResultMap">

        select * from t_emp where emp_id = #{id}

    </select>

</mapper>

    @Test

    public void queryEmpById(){

        SqlSession sqlSession = SqlSessionUtil.getSqlSession();

        EmpMapper mapper = sqlSession.getMapper(EmpMapper.class);

        Emp emp = mapper.queryEmpById(2);

        System.out.println(emp);

        sqlSession.close();

    }