Foreword:
JSONArray: equivalent to List<-Object>
JSONObject: equivalent to Map<String, Object>
1、List<Map<String, Object>> 转为 json（String）
String sql=" select * from table";
List<Map<String, Object>> list= jdbcTemplate.queryForList(sql);
String str = JSON.toJSONString(list); //此行转换
json format data:
[{
"formid": "1",
"fieldname": "ID",
"xh": 1,
"bz": "1",
"fieldzhname": "ID",
"id": "9b3ef259-4ea5-4137-ad8d-2c4f3534ae12",
"pkey": 1
}, {
"formid": "1",
"fieldname": "VERSION",
"xh": 2,
"bz": "2",
"fieldzhname": "数据版本",
"id": "858b7e4d-ec6f-480d-b5e7-dbad91b040eb",
"pkey": 0
}]
2、 json 转为 List<Map<String, Object>>
String json="[{XXXXXX}]";
List< Map<String,Object>> listw = toListMap(json); //此行转换
public static List<Map<String, Object>> toListMap(String json){
List<Object> list =JSON.parseArray(json);
List< Map<String,Object>> listw = new ArrayList<Map<String,Object>>();
for (Object object : list){
Map<String,Object> ageMap = new HashMap<String,Object>();
Map <String,Object> ret = (Map<String, Object>) object;//取出list里面的值转为map
listw.add(ret);
}
return listw;
}
3. JSON.parse() changes the json string to an object
Type: list—string—object
List<Map<String,Object>> list=jdbcTemplate.queryForList(sql);
hashmap.put("fielddata",JSON.parse(JSON.toJSONString(list)));
4. Convert json to List<entity>
The imported packages are:
import cn.hutool.json.JSONUtil;
import com.alibaba.fastjson.JSON;
import cn.hutool.json.JSONArray;
import com.alibaba.fastjson.JSONObject
List<Entity> list =new LinkedList<>();
String json="[{XXXXXX}]";
JSONArray picArray = new JSONArray(json);
list = JSONUtil.toList(picArray , Entity.class);
5. Convert List<Entity> to json (String)
import cn.hutool.json.JSONUtil;
import com.alibaba.fastjson.JSON;
import cn.hutool.json.JSONArray;
import com.alibaba.fastjson.JSONObject
// List<Entity> list
String json=JSON.toJSON(list).toString();