1 创建省市区的数据库

CREATE TABLE "area_city" (
  "id" int8 NOT NULL DEFAULT nextval('tb_national_city_id_seq'::regclass),
  "code" text COLLATE "pg_catalog"."default",
  "name" text COLLATE "pg_catalog"."default",
  "invite_code" text COLLATE "pg_catalog"."default",
  "parent_id" int8 DEFAULT 0,
  "parent_code" text COLLATE "pg_catalog"."default",
  "create_at" timestamp(6),
  "pin_name" text COLLATE "pg_catalog"."default",
  CONSTRAINT "tb_national_city_pkey" PRIMARY KEY ("id")
)
;

2 插入北京的数据

INSERT INTO "public"."tb_national_city" ("id", "code", "name", "invite_code", "parent_id", "parent_code", "create_at", "pin_name") VALUES (2, '110000', '北京市', '0', 0, '', '2018-05-08 15:30:29', 'beijingshi');
INSERT INTO "public"."tb_national_city" ("id", "code", "name", "invite_code", "parent_id", "parent_code", "create_at", "pin_name") VALUES (1, '110100', '北京市', '0', 2, '0', '2018-05-08 15:30:29', 'beijingshi');
INSERT INTO "public"."tb_national_city" ("id", "code", "name", "invite_code", "parent_id", "parent_code", "create_at", "pin_name") VALUES (3, '110101', '东城区', '0', 1, '0', '2018-05-08 15:30:29', 'dongchengqu');

INSERT INTO "public"."tb_national_city" ("id", "code", "name", "invite_code", "parent_id", "parent_code", "create_at", "pin_name") VALUES (37, '130000', '河北省', 'A', 0, NULL, '2018-05-08 15:30:29', 'hebeisheng');

INSERT INTO "public"."tb_national_city" ("id", "code", "name", "invite_code", "parent_id", "parent_code", "create_at", "pin_name") VALUES (38, '130100', '石家庄市', 'A', 37, 'A', '2018-05-08 15:30:29', 'shijiazhuangshi');

INSERT INTO "public"."tb_national_city" ("id", "code", "name", "invite_code", "parent_id", "parent_code", "create_at", "pin_name") VALUES (40, '130102', '长安区', NULL, 38, 'A', '2018-05-08 15:30:29', 'changanqu');

3 遍历数据

public class AreaCity  {
    private String code;
    private String name;
    private String inviteCode;
    private Long parentId = 0L;
    private String parentCode;
    private String pinName;
    private List<AreaCity> child = new ArrayList();
    private String parentName;
    public AreaCity() {
    }
}

(方法一)

public List<AreaCity> listViewableCityEntityexc(String key){
        List<AreaCity> list = nationalCityDao.listCityByParentId();
        List<AreaCity> shengListoneLevelRegion = list.stream().filter(item -> item.getParentId().intValue()==0).collect(Collectors.toList());
        //遍历一级地区
        if(AreaEnums.SHI.name().equals(key)) {
            shengListoneLevelRegion.stream().forEach(oneItem ->
                    {
                        //获得二级
                        List<AreaCity> twoLevelRegion = list.stream().filter(twoItem -> twoItem.getParentId().intValue() == oneItem.getId().intValue())
                                .collect(Collectors.toList());
                        //遍历二级
                        if (AreaEnums.QU.name().equals(key)) {
                            twoLevelRegion.stream().forEach(twoItem ->
                            {
                                //获得三级
                                List<AreaCity> threeLevelRegion = list.stream().filter(threeItem -> threeItem.getParentId().intValue() == twoItem.getId().intValue())
                                        .collect(Collectors.toList());
                                twoItem.setChild(threeLevelRegion);
                            });
                        }
                        oneItem.setChild(twoLevelRegion);
                    }
            );
        }
        return shengListoneLevelRegion;
    }

(方法二)

public List<NationalCity> listViewableCityEntityexc(){
        List<NationalCity> list = nationalCityDao.listCityByParentId();
        List<NationalCity> shengListoneLevelRegion = list.stream().filter(item -> item.getParentId().intValue()==0).collect(Collectors.toList());
        //遍历一级地区
            shengListoneLevelRegion.stream().forEach(oneItem ->
                    {
                        //获得二级
                        List<NationalCity> twoLevelRegion = list.stream().filter(twoItem -> twoItem.getParentId().intValue() == oneItem.getId().intValue())
                                .collect(Collectors.toList());
                        //遍历二级
                            twoLevelRegion.stream().forEach(twoItem ->
                            {
                                //获得三级
                                List<NationalCity> threeLevelRegion = list.stream().filter(threeItem -> threeItem.getParentId().intValue() == twoItem.getId().intValue())
                                        .collect(Collectors.toList());
                                twoItem.setChild(threeLevelRegion);
                            });
                        oneItem.setChild(twoLevelRegion);
                    }
            );
        return shengListoneLevelRegion;
    }

4 返回的数据

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