一：代码处理1.多表父子级关系利用流来处理private List<AddressInfo> children;List<AddressInfo> collect1 = addressInfo.stream().map(m1 -> {List<AddressInfo> collect = addressInfo.stream().filter( m2 -> Objects.equals(m1.getId(), m2.getPId())).collect(Collectors.toList());m1.setChildren(collect);return m1; }).collect(Collectors.toList());说明：m1 父级信息 m2 子级信息 2单表父子级关系处理List<Map<String, Object>> list = new ArrayList<Map<String, Object>>(); /** * 3.循环处理全部数据，转为父子级对象 */ for (AddressInfo vo : addressInfo) { Map<String, Object> map = new HashMap<String, Object>(8); if (vo.getPId() == 0) { map.put("children", getChildren(addressInfo, vo.getId())); map.put("pId", vo.getPId()); 存放子级数据 list.add(map); } } PageInfo<AddressInfo> pageInfo = new PageInfo<>(addressInfo); return success(list, pageInfo.getTotal());}public List<Map<String, Object>> getChildren(List<AddressInfo> data, Integer wzflid) { /** * 1.对数据校验处理 */ List<Map<String, Object>> list = new ArrayList<Map<String, Object>>(); if (data == null || data.size() == 0 || wzflid == null) { return list; } /** * 2.遍历匹配父子级关系数据 */ for (AddressInfo vo : data) { Map<String, Object> map = new HashMap<String, Object>(8); if (wzflid.equals(vo.getPId())) { map.put("pId", vo.getPId()); list.add(map); } } return list;}二：mysql 查询语句处理1、创建接收类型（实体类有 接受子结果的数据类型） <resultMap type="实体类" id="fatherMap"> <id column="id" property="id"/> <collection property="children" ofType="com.wengegroup.entity.UPerm" column="id" select="findMenuByPid"/></resultMap><!--级联查询父菜单--> <select id="selectUPerm" resultMap="fatherMap"> select * from u_perm where id = #{id}</select><!--级联查询子菜单--><select id="findMenuByPid" resultMap="fatherMap" > select * from u_perm where parent_id = #{id}</select>
