json格式，分为 中国>大区>省>市>区县。。按全国7大区分的。
"id": 1,
"pid": 0,
"district_code": "",
"district_name": "中国",
"type": 0,
"hierarchy": 0,
"chindren": [
{
"id": 2,
"pid": 1,
"district_code": "",
"district_name": "东北大区",
"type": 0,
"hierarchy": 1,
"chindren": [
{
"id": 186,
"pid": 2,
"district_code": "230000",
"district_name": "黑龙江省",
"type": 1,
"hierarchy": 2,
"chindren": [
{
"id": 187,
"pid": 186,
"district_code": "232700",
"district_name": "大兴安岭地区",
"type": 2,
"hierarchy": 3,
"chindren": [
{
"id": 188,
"pid": 187,
"district_code": "232722",
"district_name": "塔河县",
"type": 3,
"hierarchy": 4
},
