java递归生成树形结构数据

java递归生成树形结构数据，以查询省、市、区树形结构为例
service层代码

    @Autowired
    private AreaDao dao;

    /**
     * 获取省、市、区树形结构数据
     */
    public Area getTree(int id) {
        Area area = dao.findAreaById(id);
        if (area != null) {
            List<Area> childAreas = dao.findChildByParentId(area.getParentId());
            if (CollectionUtils.isNotEmpty(childAreas)) {
                area.setChildAreas(childAreas);
                recursive(childAreas);
            }
        }
        return area;
    }

    /**
     * 递归查询数据
     */
    public void recursive(List<Area> areas) {
        for (Area area : areas) {
            List<Area> childAreas = dao.findChildByParentId(area.getParentId());
            if (CollectionUtils.isNotEmpty(childAreas)) {
                area.setChildAreas(childAreas);
                recursive(areas);
            }
        }
    }

dao层sql查询代码

    <select id="findAreaById" parameterType="int" resultMap="BaseResultMap">
        select * from area where id = #{id}
    </select>

    <select id="findChildByParentId" parameterType="int" resultMap="BaseResultMap">
        select * from area where parent_id = #{parentId}
    </select>

实体类代码

@Data
public class Area {
    @ApiModelProperty(value = "地点id")
    private int areaId;

    @ApiModelProperty(value = "地点名称")
    private String name;

    @ApiModelProperty(value = "地点父id")
    private int parentId;

    @ApiModelProperty(value = "下级地点")
    private List<Area> childAreas;
}

本文地址：https://blog.csdn.net/oracle_a/article/details/109277057