Mybatis之自定义映射resultMap

<resultMapid="empResultMap"type="Emp"><idproperty="eid"column="eid"></id><resultproperty="empName"column="emp_name"></result><resultproperty="age"column="age"></result><resultproperty="sex"column="sex"></result><resultproperty="email"column="email"></result></resultMap><!--List<Emp>getAllEmp();--><selectid="getAllEmp"resultMap="empResultMap">select*fromt_emp</select>

<!--List<Emp>getAllEmp();--><selectid="getAllEmp"resultType="Emp">selecteid,emp_nameempName,age,sex,emailfromt_emp</select>

<settings><settingname="mapUnderscoreToCamelCase"value="true"/></settings>

publicclassEmp {  
privateIntegereid;  
privateStringempName;  
privateIntegerage;  
privateStringsex;  
privateStringemail;  
privateDeptdept;
//...构造器、get、set方法等}

<resultMapid="empAndDeptResultMapOne"type="Emp"><idproperty="eid"column="eid"></id><resultproperty="empName"column="emp_name"></result><resultproperty="age"column="age"></result><resultproperty="sex"column="sex"></result><resultproperty="email"column="email"></result><resultproperty="dept.did"column="did"></result><resultproperty="dept.deptName"column="dept_name"></result></resultMap><!--EmpgetEmpAndDept(@Param("eid")Integereid);--><selectid="getEmpAndDept"resultMap="empAndDeptResultMapOne">select*fromt_empleftjoint_deptont_emp.eid=t_dept.didwheret_emp.eid=#{eid}
</select>

<resultMapid="empAndDeptResultMapTwo"type="Emp"><idproperty="eid"column="eid"></id><resultproperty="empName"column="emp_name"></result><resultproperty="age"column="age"></result><resultproperty="sex"column="sex"></result><resultproperty="email"column="email"></result><associationproperty="dept"javaType="Dept"><idproperty="did"column="did"></id><resultproperty="deptName"column="dept_name"></result></association></resultMap><!--EmpgetEmpAndDept(@Param("eid")Integereid);--><selectid="getEmpAndDept"resultMap="empAndDeptResultMapTwo">select*fromt_empleftjoint_deptont_emp.eid=t_dept.didwheret_emp.eid=#{eid}
</select>

//EmpMapper里的方法/*** 通过分步查询，员工及所对应的部门信息* 分步查询第一步：查询员工信息* @param  * @return com.atguigu.mybatis.pojo.Emp* @date 2022/2/27 20:17*/EmpgetEmpAndDeptByStepOne(@Param("eid") Integereid);

<resultMapid="empAndDeptByStepResultMap"type="Emp"><idproperty="eid"column="eid"></id><resultproperty="empName"column="emp_name"></result><resultproperty="age"column="age"></result><resultproperty="sex"column="sex"></result><resultproperty="email"column="email"></result><associationproperty="dept"select="com.atguigu.mybatis.mapper.DeptMapper.getEmpAndDeptByStepTwo"column="did"></association></resultMap><!--EmpgetEmpAndDeptByStepOne(@Param("eid") Integereid);--><selectid="getEmpAndDeptByStepOne"resultMap="empAndDeptByStepResultMap">select*fromt_empwhereeid=#{eid}
</select>

//DeptMapper里的方法/*** 通过分步查询，员工及所对应的部门信息* 分步查询第二步：通过did查询员工对应的部门信息* @param* @return com.atguigu.mybatis.pojo.Emp* @date 2022/2/27 20:23*/DeptgetEmpAndDeptByStepTwo(@Param("did") Integerdid);

<!--此处的resultMap仅是处理字段和属性的映射关系--><resultMapid="EmpAndDeptByStepTwoResultMap"type="Dept"><idproperty="did"column="did"></id><resultproperty="deptName"column="dept_name"></result></resultMap><!--DeptgetEmpAndDeptByStepTwo(@Param("did") Integerdid);--><selectid="getEmpAndDeptByStepTwo"resultMap="EmpAndDeptByStepTwoResultMap">select*fromt_deptwheredid=#{did}
</select>

publicclassDept {
privateIntegerdid;
privateStringdeptName;
privateList<Emp>emps;
//...构造器、get、set方法等}

<resultMapid="DeptAndEmpResultMap"type="Dept"><idproperty="did"column="did"></id><resultproperty="deptName"column="dept_name"></result><collectionproperty="emps"ofType="Emp"><idproperty="eid"column="eid"></id><resultproperty="empName"column="emp_name"></result><resultproperty="age"column="age"></result><resultproperty="sex"column="sex"></result><resultproperty="email"column="email"></result></collection></resultMap><!--DeptgetDeptAndEmp(@Param("did") Integerdid);--><selectid="getDeptAndEmp"resultMap="DeptAndEmpResultMap">select*fromt_deptleftjoint_empont_dept.did=t_emp.didwheret_dept.did=#{did}
</select>

/*** 通过分步查询，查询部门及对应的所有员工信息* 分步查询第一步：查询部门信息* @param did * @return com.atguigu.mybatis.pojo.Dept* @date 2022/2/27 22:04*/DeptgetDeptAndEmpByStepOne(@Param("did") Integerdid);

<resultMapid="DeptAndEmpByStepOneResultMap"type="Dept"><idproperty="did"column="did"></id><resultproperty="deptName"column="dept_name"></result><collectionproperty="emps"select="com.atguigu.mybatis.mapper.EmpMapper.getDeptAndEmpByStepTwo"column="did"></collection></resultMap><!--DeptgetDeptAndEmpByStepOne(@Param("did") Integerdid);--><selectid="getDeptAndEmpByStepOne"resultMap="DeptAndEmpByStepOneResultMap">select*fromt_deptwheredid=#{did}
</select>

/*** 通过分步查询，查询部门及对应的所有员工信息* 分步查询第二步：根据部门id查询部门中的所有员工* @param did* @return java.util.List<com.atguigu.mybatis.pojo.Emp>* @date 2022/2/27 22:10*/List<Emp>getDeptAndEmpByStepTwo(@Param("did") Integerdid);

<!--List<Emp>getDeptAndEmpByStepTwo(@Param("did") Integerdid);--><selectid="getDeptAndEmpByStepTwo"resultType="Emp">select*fromt_empwheredid=#{did}
</select>

<settings><!--开启延迟加载--><settingname="lazyLoadingEnabled"value="true"/></settings>

@TestpublicvoidgetEmpAndDeptByStepOne() {
SqlSessionsqlSession=SqlSessionUtils.getSqlSession();
EmpMappermapper=sqlSession.getMapper(EmpMapper.class);
Empemp=mapper.getEmpAndDeptByStepOne(1);
System.out.println(emp.getEmpName());
}

@TestpublicvoidgetEmpAndDeptByStepOne() {
SqlSessionsqlSession=SqlSessionUtils.getSqlSession();
EmpMappermapper=sqlSession.getMapper(EmpMapper.class);
Empemp=mapper.getEmpAndDeptByStepOne(1);
System.out.println(emp.getEmpName());
System.out.println("----------------");
System.out.println(emp.getDept());
}

<resultMapid="empAndDeptByStepResultMap"type="Emp"><idproperty="eid"column="eid"></id><resultproperty="empName"column="emp_name"></result><resultproperty="age"column="age"></result><resultproperty="sex"column="sex"></result><resultproperty="email"column="email"></result><associationproperty="dept"select="com.atguigu.mybatis.mapper.DeptMapper.getEmpAndDeptByStepTwo"column="did"fetchType="lazy"></association></resultMap>