java JSON对象与字符串间的转换

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;

//字符串转为JSON对象
String strParam="{ \"callerid\": \"013941128270\" ,\"timestart\": \"2021-07-27 09:37:42\" , \"status\": \"ANSWERED\" }";
//将字符串转化成JSONObject
JSONObject jsonParam= JSON.parseObject(strParam);

//实例一个JSON对象 并赋值
JSONObject jsonParam = new JSONObject();
jsonParam.put("event","NewCdr");
jsonParam.put("callid","1627349862.433");
jsonParam.put("timestart","2021-07-27 09:37:42");
jsonParam.put("callfrom","1008");

//取JSON中的某个值
String event = jsonObj.get("event").toString();
String callid = jsonObj.get("callid").toString();

//得到一个JSON字符串
jsonParam.toJSONString()