mybatis 06 对多关联

概念：

一个部门对应多个员工
部门表中有List员工属性

案例：

配置文件
myBatis-conf.xml

<!--别名-->
    <typeAliases>
        <typeAlias type="com.xxjqr.relation02.Emp" alias="Emp"/>
        <typeAlias type="com.xxjqr.relation02.Dept" alias="Dept"/>
    </typeAliases>

<!---关联配置文件-->
<mappers>

        <mapper resource="com/xxjqr/relation02/empMapper.xml"/>
        <mapper resource="com/xxjqr/relation02/deptMapper.xml"/>
</mappers>

deptMapper.xml

<?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="com.xxjqr.relation02.deptMapper">

    <resultMap type="Dept" id="deptResultMap">
        <id column="dept_id" property="deptId"/>
        <result column="dept_name" property="deptName"/>
        <result column="dept_address" property="deptAddress"/>
        <!--collection用来配置对多的关联  -->
        <collection property="emps" resultMap="com.xxjqr.relation02.empMapper.empResultMap"></collection>
    </resultMap>
    
    <!-- 根据部门名称查询部门信息（包括部门员工信息） -->
    <select id="selectDeptEmpList" parameterType="string" resultMap="deptResultMap">
        select e.*,d.* from emp_t e inner join dept_t d on e.dept_id = d.dept_id
        where d.dept_name = #{deptName} 
    </select>
</mapper>

empMapper.xml

<?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="com.xxjqr.relation02.empMapper">

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

    <id column="emp_id" property="empId"/>
    <result column="emp_name" property="empName"/>
    <result column="emp_sex" property="empSex"/>

</resultMap>

</mapper>

类

@Data
public class Dept {
    private int deptId;
    private String deptName;
    private String deptAddress;
    private List<Emp> emps;
}

@Data
public class Emp {
    private String empId;
    private String empName;
    private String empSex;
}

public class UserDao {
    public List<Dept> selectList (String name){
        List<Dept> depts = null;
        SqlSession session = null;
        try {
            session = MybatisSessionFactory.getSession();
            depts = session.selectList("com.xxjqr.relation02.deptMapper.selectDeptEmpList",name);
            session.commit();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                MybatisSessionFactory.closeSession();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        
        return depts;
    }
}

public class TestUserDao {
    private UserDao userDao = new UserDao();
    
    @Test
    public void test(){
        List<Dept> depts = null;
        depts = userDao.selectList("开发部");
        System.out.println(depts);
    }
}

MybatisSessionFactory