mybatis关联查询多对一

public class Dept {
	private Integer deptid;
	private String dname;
	private String dloc;
}

public class Emp {
	private Integer empid;
	private String ename;
	private String esex;
	private Date ehiredate;
	private Double esal;
	private Dept dept;
}

public interface EmpMapper {
	public List<Emp> selectAllEmp();
	public List<Emp> selectAllEmp2();
}

<mapper namespace="com.gx.mapper.EmpMapper">
	
	<resultMap type="Emp" id="BaseEmp">
		<id property="empid" column="empid" />
		<result property="ename" column="ename"/>
		<result property="esex" column="esex"/>
		<result property="ehiredate" column="ehiredate"/>
		<result property="esal" column="esal"/>
	
	</resultMap>
	<resultMap type="Emp" id="myEmp" extends="BaseEmp">
		<!-- 建立关系 
			property="dept"   指emp里面的dept属性
			javaType 指emp属性的类型
		-->
		<association property="dept"  javaType="com.gx.domain.Dept" >
			<id property="deptid" column="deptid"/>
			<result property="dname" column="dname"/>
			<result property="dloc" column="dloc"/>
		</association>
	</resultMap>
	
	<select id="selectAllEmp"  resultMap="myEmp">
		select * from emp inner join dept using(deptid)
	</select>
	
		<resultMap type="Emp" id="myEmp2" extends="BaseEmp">
		<!-- 建立关系 
			property="dept"   指emp里面的dept属性
			javaType 指emp属性的类型
			column="deptid" 从当前的结果集里面取出deptid，传给com.gx.mapper.DeptMapper.selectDeptById
		-->
		<association property="dept"  column="deptid" select="com.gx.mapper.DeptMapper.selectDeptById">
		</association>
	</resultMap>
		<select id="selectAllEmp2"  resultMap="myEmp2">
		select * from emp inner join dept using(deptid)
	</select>
	
</mapper>

<mapper namespace="com.gx.mapper.DeptMapper">
	<!--  根据部门编号查询部门信息-->
	<select id="selectDeptById" resultType="Dept">
		select * from dept where deptid=#{deptid}
	</select>
	
</mapper>

public class myTest {
	SqlSession session = MyBatisUtils.openSession();
	EmpMapper empMapper = session.getMapper(EmpMapper.class);
	
	@Test
	public void selectAllEmp() {
		List<Emp> list = empMapper.selectAllEmp();
		for (Emp emp : list) {
			System.out.println(emp);
		}
		MyBatisUtils.closeSession(session);
	}
	
	@Test
	public void selectAllEmp2() {
		List<Emp> list = empMapper.selectAllEmp2();
		for (Emp emp : list) {
			System.out.println(emp);
		}
		MyBatisUtils.closeSession(session);
	}
}