环境

使用 springboot + MyBatis-Plus (简化 mybatis 开发) + lombok （注解 gettter、setter）

实体类 Dto

@[Data](https://hacpai.com/member/Data) 
@[TableName](https://hacpai.com/member/TableName) ("xxx 表名")
public class Organize extends Model<Organize> {


    @TableId(type = IdType.AUTO)
    private String id;

    private String code;

    private String name;

    private String uporgId;

    @TableField(exist = false)
    private List<Organize> child;


    /** 指定主键 */
    @Override
    protected Serializable pkVal() {
        return this.id;
    }

}

controlller 省略

service 实现

@Service
public class OrganizeServiceImpl implements OrganizeService {

    @Autowired
    @SuppressWarnings("all")
    private OrganizeMapper organizeMapper;

    @Override
    public List<Organize> tree(Organize organize) {
        long startTime = System.currentTimeMillis();

        // 查出全部 获取根节点 list
        List<Organize> organizes = organizeMapper.selectList(null);
        List<Organize> childList = new ArrayList<Organize>();
        for (Organize o : organizes) {
            if (StringUtils.isNullOrEmpty(o.getUporgId())) {
                childList.add(o);
            }
        }

        // 开始递归
        List<Organize> resultTree = setChildren(childList, organizes);

        long endTime = System.currentTimeMillis();
        // 输出程序运行时间
        System.out.println("程序运行时间：" + (endTime - startTime) + "ms");
        return resultTree;
    }


    public List<Organize> setChildren(List<Organize> resultTree, List<Organize> allList) {

        for (int i = 0; i < resultTree.size(); i++) {
            Organize item = resultTree.get(i);

            // 从全部数据中查询上级节点为当前节点 id 的数据 作为当前节点的子节点
            List<Organize> resultChildren = new ArrayList<Organize>();
            for (Organize o : allList) {
                if (null != o.getUporgId() && o.getUporgId().equals(item.getId())) {
                    resultChildren.add(o);
                }
            }

            if (!resultChildren.isEmpty()) {
                // 递归
                resultChildren = setChildren(resultChildren, allList);
                // 设置子集
                item.setChild(resultChildren);
                resultTree.set(i, item);
            }
        }
        return resultTree;
    }
}