文章目錄

• • • 1、創建表結構
    • 2、EmployeeMapper接口
    • 3、EmployeeMapper.xml
    • 4、Test

1、創建表結構

CREATE TABLE `mybatis`.`dept` (`id` INT NOT NULL ,`dept_name` VARCHAR(45) NULL ,PRIMARY KEY (`id`) );alter table employee add d_id INT(45);INSERT INTO `mybatis`.`dept` (`id`, `dept_name`) VALUES ('1', '開發部'); INSERT INTO `mybatis`.`dept` (`id`, `dept_name`) VALUES ('2', '測試部');

2、EmployeeMapper接口

package com.mi.dao;import com.mi.pojo.Employee; import org.apache.ibatis.annotations.MapKey; import org.apache.ibatis.annotations.Param;import java.util.List; import java.util.Map;public interface EmployeeMapper {//查詢員工及部門public Employee getEmpAndDept(Integer id); }

3、EmployeeMapper.xml

<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd"> <!--指定為接口的全類名--> <mapper namespace="com.mi.dao.EmployeeMapper"><!--聯合查詢，級聯屬性封裝結果集--><resultMap id="myEmpAndEmp" type="com.mi.pojo.Employee"><id column="id" property="id"/><result column="last_name" property="lastName"/><result column="gender" property="gender"/><result column="d_id" property="dept.id"/><result column="dept_name" property="dept.deptName"/></resultMap><!--關聯查詢員工及部門--><select id="getEmpAndDept" resultMap="myEmpAndEmp">select e.id,e.last_name, e.gender,d.id d_id,d.dept_name dept_namefrom employee e ,dept dwhere e.d_id = d.id and e.id = #{id}</select> </mapper>

4、Test

@Testpublic void getEmpAndDept() throws IOException {//1、獲取SqlSessionFactory對象SqlSessionFactory sqlSessionFactory = getSqlSessionFactory();//2、獲取Sqlsesion對象SqlSession sqlSession = sqlSessionFactory.openSession();try {//3、獲取接口的實現類對象//會為接口自動創建一個代理對象，代理對象去執行增刪改查方法EmployeeMapper mapper = sqlSession.getMapper(EmployeeMapper.class);Employee employee = mapper.getEmpAndDept(3);System.out.println(employee);System.out.println(employee.getDept());}finally {sqlSession.close();}}

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