JSONObject jo_str = JSONObject.parseObject(jsonStr); String responseData = JSON.toJSONString(jo_str, SerializerFeature.PrettyFormat, SerializerFeature.WriteMapNullValue, SerializerFeature.WriteDateUseDateFormat);

JSONObject jo_str = JSONObject.parseObject(jsonStr); String responseData = JSON.toJSONString(jo_str, SerializerFeature.PrettyFormat, SerializerFeature.WriteMapNullValue, SerializerFeature.WriteDateUseDateFormat);