Mybatis 遍历 List<Map<String,Object>>

在上一篇博客中总结了MyBatis Plus 实现多表分页模糊查询（链接在最后）。返回类型是编写一个专门的vo类。这次是返回List < Map >

前言

编写一个专门的vo返回类，主要原因是如果其他地方也要用到到这个返回结果类，相比于map，返回类比较方便处理。

但是，这次的返回类型吧并不常用，所以就考虑了List<Map<String,Object>>

解决

在上一篇博客的基础,我们需要将返回类型换成List<Map<String,Object>>

下面举一个例子，演示一下。

controller

@PostMapping("getAll")
public Result getAll(@RequestBody DormitoryStudent dormitoryStudent){
    List<Map<String,Object>> stus  =  dormitoryStudentService.getList(dormitoryStudent.getDormitoryId());
    return  Result.ok().data("list",stus);
}

service

public interface DormitoryStudentService extends IService<DormitoryStudent> {

    List<Map<String,Object>> getList(Integer dormitoryId);
}

serviceImpl

@Service
public class DormitoryStudentServiceImpl extends ServiceImpl<DormitoryStudentMapper, DormitoryStudent> implements DormitoryStudentService {

    @Override
    public List<Map<String,Object>> getList(Integer dormitoryId) {
        List<Map<String,Object>> stus = this.baseMapper.getList(dormitoryId);
        return stus;
    }
}

mapper

public interface DormitoryStudentMapper extends BaseMapper<DormitoryStudent> {

    List<Map<String,Object>> getList(@Param("dormitory_id") Integer dormitoryId);
}

mapper.xml

非常重要的一个点 resultType="java.util.HashMap"

<?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.dj.dormitory.mapper.DormitoryStudentMapper">
    <select id="getList" resultType="java.util.HashMap">
        select tb_user.name student_name,tb_student.sno
        from tb_student
        left outer join tb_user on tb_user.id = tb_student.user_id
        left outer join tb_dormitory_student on tb_dormitory_student.student_id = tb_student.id
        where tb_dormitory_student.dormitory_id = #{dormitory_id}
    </select>
</mapper>