JavaWeb - 多级菜单分组嵌套“递归”写法

Posted 2021-05-29 Lux_Sun

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<ApiGroupPO> 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
 */
@Override
public List<ApiGroupPO> getGroupListByType() {
    QueryWrapper<ApiGroupPO> qw = new QueryWrapper<>();
    qw.orderByDesc(Const.Group.COLUMN_GROUPUPDATETIME);
    List<ApiGroupPO> apiGroupPoList = groupDao.selectList(qw);
    apiGroupPoList = dealApiGroupLayer(apiGroupPoList);
    return apiGroupPoList;
}

/**
 * [OK]
 * 处理分组层级
 * @param apiGroupList
 */
private List<ApiGroupPO> dealApiGroupLayer(List<ApiGroupPO> apiGroupList) {
    Map<String, ApiGroupPO> id2GroupMap = apiGroupList.stream().collect(Collectors.toMap(ApiGroupPO::getGroupId, apiGroupPO -> apiGroupPO));
    List<ApiGroupPO> 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;
}