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设计思路：最简单的查询全部分组数据，然后通过 Java 程序控制分层问题，借用临时 Map 来快速定位父子分组关系噢~

• SQL

DROP TABLE IF EXISTS `t_ac_api_group`;CREATE TABLE `t_ac_api_group` (  `group_id` varchar(32) NOT NULL COMMENT '分组Id',  `group_name` varchar(30) NOT NULL COMMENT '分组名称',  `group_pid` varchar(32) NOT NULL COMMENT '分组父Id',  `group_type` tinyint(1) NOT NULL COMMENT '分组类型',  `group_del` tinyint(1) NOT NULL,  `group_createtime` datetime NOT NULL,  `group_updatetime` datetime NOT NULL,  PRIMARY KEY (`group_id`) USING BTREE) ENGINE=InnoDB DEFAULT CHARSET=utf8;

• 伪代码

import com.baomidou.mybatisplus.annotation.*;import com.fasterxml.jackson.annotation.JsonInclude;import lombok.AllArgsConstructor;import lombok.Builder;import lombok.Data;import lombok.NoArgsConstructor;import java.time.LocalDateTime;import java.util.List;/** * @author Lux Sun * @date 2020/6/5 */@Data@Builder@NoArgsConstructor@AllArgsConstructor@TableName("t_ac_api_group")public class ApiGroupPO {    @TableId(type = IdType.ASSIGN_UUID)    private String groupId;    private String groupName;    private String groupPid;    private Integer groupType;    @TableField(exist = false)    private List
   
     groupList;    @TableLogic    @TableField(fill = FieldFill.INSERT, select = false)    private Integer groupDel;    @TableField(fill = FieldFill.INSERT)    private LocalDateTime groupCreatetime;    @TableField(fill = FieldFill.INSERT_UPDATE)    private LocalDateTime groupUpdatetime;}
   

/** * [OK] * 获取根分组集 * @return */@Overridepublic List
   
     getGroupListByType() {    QueryWrapper
    
      qw = new QueryWrapper<>();    qw.orderByDesc(Const.Group.COLUMN_GROUPUPDATETIME);    List
     
       apiGroupPoList = groupDao.selectList(qw);    apiGroupPoList = dealApiGroupLayer(apiGroupPoList);    return apiGroupPoList;}/** * [OK] * 处理分组层级 * @param apiGroupList */private List
      
        dealApiGroupLayer(List
       
         apiGroupList) {    Map
        
          id2GroupMap = apiGroupList.stream().collect(Collectors.toMap(ApiGroupPO::getGroupId, apiGroupPO -> apiGroupPO)); List
         
           finalApiGroupPoList = Lists.newArrayList(); for (ApiGroupPO apiGroupPo : apiGroupList) { String groupPid = apiGroupPo.getGroupPid(); if (Const.Group.VAL_GROUPPIDROOT.equals(groupPid)) { finalApiGroupPoList.add(apiGroupPo); continue; } ApiGroupPO apiParentGroupPo = id2GroupMap.get(groupPid); // 如果为空, new List 赋值过去; 不为空也不影响, 大不了自己 set 自己一下 apiParentGroupPo.setGroupList(Optional.ofNullable(apiParentGroupPo.getGroupList()).orElse(Lists.newArrayList())); apiParentGroupPo.getGroupList().add(apiGroupPo); } return finalApiGroupPoList;}
         
        
       
      
     
    
   

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