public void getTrajectory() {
		String user_id;
		try {
			user_id = request.getParameter("user_id").trim();
		} catch (Exception e) {
			jsonObject.put("RC", RC.PARAMETER_ERROR);
			return;
		}

		List<?> list;
		try {
			list = new UserLocationDao().getTrajectory(user_id);
		} catch (Exception e) {
			jsonObject.put("RC", RC.SQL_EXCEPTION);
			return;
		}
		if (list != null) {
			jsonObject.put("OC", OC.SUCCESS);
			jsonObject.put("trajectory_count", list.size());
			jsonObject.put("trajectory", JSONArray.fromObject(list));
		}
	}