普通方式

public class Employee {private Integer id;private String lastName;private String email;private String gender;private Department dept;} public class Department {private Integer id;private String departmentName;} public interface EmployeeMapperPlus {public Employee getEmpAndDept(Integer id);} <resultMap id="MyDifEmp" type="com.atguigu.mybatis.bean.Employee"><id column="id" property="id"></id><result column="last_name" property="lastName"></result><result column="gender" property="gender"></result><result column="did" property="dept.id"></result><result column="dept_name" property="dept.departmentName"></result></resultMap><!-- public Employee getEmpAndDept(Integer id);--><select id = "getEmpAndDept" resultMap="MyDifEmp">SELECT e.id id,e.last_name last_name,e.gender gender ,e.d_id d_id,d.id did,d.dept_name dept_name FROM tb1_employee e,tb1_dept d WHERE e.d_id = d.id AND e.id = #{id};</select> @Testpublic void test03() throws IOException {SqlSessionFactory sqlSessionFactory = getSqlSessionFactory();SqlSession sqlSession = sqlSessionFactory.openSession();try{EmployeeMapperPlus mapper = sqlSession.getMapper(EmployeeMapperPlus.class);Employee emp = mapper.getEmpAndDept(1);System.out.println(emp);System.out.println(emp.getDept());}finally {sqlSession.close();}}

association

• 注意用了association之后，不能自動封裝，必須指定全部屬性

<!-- 使用association定義關聯的單個對象的封裝規則--><resultMap id="MyDifEmp" type="com.atguigu.mybatis.bean.Employee"><id column="id" property="id"></id><result column="last_name" property="lastName"></result><result column="gender" property="gender"></result><!--association可以指定聯合的javaBean對象property = "dept":指定哪個屬性是聯合的對象--><association property="dept" javaType="com.atguigu.mybatis.bean.Department"><id column="did" property="id"></id><result column="dept_name" property="departmentName"></result></association></resultMap><!-- public Employee getEmpAndDept(Integer id);--><select id = "getEmpAndDept" resultMap="MyDifEmp">SELECT e.id id,e.last_name last_name,e.gender gender ,e.d_id d_id,d.id did,d.dept_name dept_name FROM tb1_employee e,tb1_dept d WHERE e.d_id = d.id AND e.id = #{id};</select>

總結

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