java如何实现嵌套对象转大map(扁平化)
嵌套对象转大map(扁平化)
部分业务场景在传输数据时，需要的数据格式是扁平化的json格式，而在java对象中有时候为了解耦会做一些嵌套（即对象中包含对象，多层也是常有）。
下面的代码可以提供该能力
- 处理单个对象：ObjectToMapUtil.nestedObj2Map
- 处理列表对象：ObjectToMapUtil.nestedObjList2ListMap
package cn.sto.station.twin.common.util;
import cn.sto.station.twin.common.util.json.JsonUtil;
import com.alibaba.fastjson.JSONObject;
import com.alibaba.fastjson.JSON;
import lombok.extern.slf4j.Slf4j;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
@Slf4j
public class ObjectToMapUtil {
private static final String SEPARATOR = "_";
public static Map<String, Object> nestedObj2Map(Object object) {
Map<String, Object> maps = JSON.parseObject(JSON.toJSONString(object), Map.class);
Map<String, Object> result = new HashMap<>();
maps.forEach((key, value) -> {
common(maps, result, key, value, key);
});
return result;
}
public static <T> List<Map<String, Object>> nestedObjList2ListMap(List<T> objectList) {
ArrayList<Map<String, Object>> resultList = new ArrayList<>();
for (T t : objectList) {
resultList.add(nestedObj2Map(t));
}
return resultList;
}
public static Map<String, Object> nestedObj2Map(Map<String, Object> maps, String prefix) {
Map<String, Object> result = new HashMap<>();
String keyPrefix = prefix + SEPARATOR;
maps.forEach((key, value) -> {
String newKey = keyPrefix + key;
common(maps, result, key, value, newKey);
});
return result;
}
public static void common(Map<String, Object> maps, Map<String, Object> result, String key, Object value, String newKey) {
if (maps.get(key) != null && value instanceof JSONObject) {
Map<String, Object> subMaps = (Map) maps.get(key);
Map<String, Object> map = nestedObj2Map(subMaps, newKey);
if (map != null && !map.isEmpty()) {
result.putAll(map);
}
} else {
result.put(newKey, maps.get(key));
}
}
}java：JSON扁平化和去扁平化
在GitHub上发现了一个比较好的JSON扁平化和去扁平化处理方法，话不多说，直接开干。
1、扁平化数据(网上找的一json大串)
"{\"type\":10,\"data\":[{\"text\":\"献给爱我们的女神\",\"is_liked\":false,\"index_cover\":\"/file/imgs/upload/202211/13/odpxnajcusq.jpg?imageView/2/w/960/q/85\",\"poi\":\"\",\"cover_image_height\":816,\"trip_id\":2387282916,\"index_title\":\"\",\"center_point\":{},\"view_count\":36207,\"location_alias\":\"\",\"cover_image_1600\":\"/file/imgs/upload/202211/13/xac0lky4mxc.jpg?imageView/2/w/1384/h/1384/q/85\",\"cover_image_s\":\"/file/imgs/upload/202211/13/xac0lky4mxc.jpg?imageView/1/w/280/h/280/q/75\",\"share_url\":\"btrip/spot/2387842143/\",\"timezone\":\"Asia/Shanghai\",\"date_tour\":\"2016-06-19T01:19:07+08:00\",\"is_hiding_location\":false,\"user\":{\"location_name\":\"\",\"name\":\"丑到没墙角\",\"resident_city_id\":\"\",\"mobile\":\"\",\"gender\":2,\"avatar_m\":\"/file/imgs/upload/202211/13/d0onzi4crrs.jpg-avatar.m\",\"cover\":\"/file/imgs/upload/202211/13/hh1ape5GClb.jpg-usercover.display\",\"custom_url\":\"\",\"experience\":{\"value\":59,\"level_info\":{\"name\":\"\",\"value\":1}},\"id\":2384288641,\"birthday\":\"\",\"country_num\":null,\"avatar_s\":\"/file/imgs/upload/202211/13/d0onzi4crrs.jpg-avatar.s\",\"country_code\":null,\"email_verified\":false,\"is_hunter\":false,\"cdc2\":false,\"avatar_l\":\"/file/imgs/upload/202211/13/d0onzi4crrs.jpg-avatar.l\",\"email\":\"\",\"user_desc\":\"\",\"points\":2},\"spot_id\":2387842143,\"is_author\":false,\"cover_image_w640\":\"/file/imgs/upload/202211/13/xac0lky4mxc.jpg?imageView/1/w/640/h/480/q/85\",\"region\":{\"primary\":\"\",\"secondary\":\"\"},\"comments_count\":2,\"cover_image\":\"/file/imgs/upload/202211/13/xac0lky4mxc.jpg?imageView/2/w/960/q/85\",\"cover_image_width\":1088,\"recommendations_count\":21}],\"desc\":\"\"}"2、maven依赖
https://github.com/wnameless/json-flattener
<dependency>
<groupId>com.github.wnameless.json</groupId>
<artifactId>json-flattener</artifactId>
<version>0.8.1</version>
</dependency>3、扁平化
public static void jsonFlatten(String jsonStr) {
JSONObject jsonObj = JSONObject.parseObject(jsonStr);
Map<String, Object> flatMap = JsonFlattener.flattenAsMap(jsonObj.toString());
for (Map.Entry<String, Object> entry : flatMap.entrySet()) {
System.out.println(entry.geTKEy() + " : " + entry.getValue());
}
}备注：扁平化级别默认.隔开，若指定级别分割任意符号：
new JsonFlattener(jsonObj.toString()).withSeparator(',').flattenAsMap();输出结果：
data[0].center_point: {}
data[0].comments_count: 2
data[0].cover_image: /file/imgs/upload/202211/13/xac0lky4mxc.jpg?imageView/2/w/960/q/85
data[0].cover_image_1600: /file/imgs/upload/202211/13/xac0lky4mxc.jpg?imageView/2/w/1384/h/1384/q/85
data[0].cover_image_height: 816
data[0].cover_image_s: /file/imgs/upload/202211/13/xac0lky4mxc.jpg?imageView/1/w/280/h/280/q/75
data[0].cover_image_w640: /file/imgs/upload/202211/13/xac0lky4mxc.jpg?imageView/1/w/640/h/480/q/85
data[0].cover_image_width: 1088
data[0].date_tour: 2016-06-19T01:19:07+08:00
data[0].index_cover: /file/imgs/upload/202211/13/odpxnajcusq.jpg?imageView/2/w/960/q/85
data[0].index_title:
data[0].is_author: false
data[0].is_hiding_location: false
data[0].is_liked: false
data[0].location_alias:
data[0].poi:
data[0].recommendations_count: 21
data[0].region.primary:
data[0].region.secondary:
data[0].share_url: btrip/spot/2387842143/
data[0].spot_id: 2387842143
data[0].text: 献给爱我们的女神
data[0].timezone: Asia/Shanghai
data[0].trip_id: 2387282916
data[0].user.avatar_l: /file/imgs/upload/202211/13/d0onzi4crrs.jpg-avatar.l
data[0].user.avatar_m: /file/imgs/upload/202211/13/d0onzi4crrs.jpg-avatar.m
data[0].user.avatar_s: /file/imgs/upload/202211/13/d0onzi4crrs.jpg-avatar.s
data[0].user.birthday:
data[0].user.cdc2: false
data[0].user.cover: /file/imgs/upload/202211/13/hh1ape5gclb.jpg-usercover.display
data[0].user.custom_url:
data[0].user.email:
data[0].user.email_verified: false
data[0].user.experience.level_info.name:
data[0].user.experience.level_info.value: 1
data[0].user.experience.value: 59
data[0].user.gender: 2
data[0].user.id: 2384288641
data[0].user.is_hunter: false
data[0].user.location_name:
data[0].user.mobile:
data[0].user.name: 丑到没墙角
data[0].user.points: 2
data[0].user.resident_city_id:
data[0].user.user_desc:
data[0].view_count: 36207
desc:
type: 10
4、去扁平化
String unflattenJson = JsonUnflattener.unflatten(flattenJson);以上为个人经验，希望能给大家一个参考，也希望大家多多支持。
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