List与json的转换

/**
	 * 根据页面用户输入的信息形成 Answer 对象的List
	 * 
	 * @param answers
	 * @param question_ids
	 * @param types
	 * @return
	 */
	private List<Answer> toAnswerList(String[] studenAnswers, int[] question_ids,
			int[] types,int[] scores) {
		List<Answer> answerList = new ArrayList<Answer>();

		if(studenAnswers!=null && question_ids!= null && types!= null&& scores!= null){
			for (int i = 0; i < studenAnswers.length; i++) {

				Answer answer = new Answer();
				String studenAnswer = studenAnswers[i];
				int type = types[i];
				int question_id = question_ids[i];
				int score = scores[i];


				answer.setQuestion_id(question_id);
				answer.setScore(score);
				answer.setStudenAnswer(studenAnswer);
				answer.setType(type);

				answerList.add(answer);
			}
		}
		return answerList;
	}

	/**
	 * 将一个json字串转为list
	 * @param props
	 * @return
	 */
	public static List<Answer> converAnswerFormString(String answer){
		if (answer == null || answer.equals(""))
			return new ArrayList();

		JSONArray jsonArray = JSONArray.fromObject(answer);
		List<Answer> list = (List) JSONArray.toCollection(jsonArray,
				Answer.class);

		return list;
	}

	/**
	 * 
	 * 将一个 Answer 对象的List 生成Json字串
	 * 是根据客户端页面用户输入的信息生成的
	 * 
	 * 
	 */
	public String getAnswerString(String[] studenAnswers, int[] question_ids,
			int[] types,int[] scores) {
		List list = toAnswerList(studenAnswers,  question_ids,
				 types, scores);
		JSONArray jsonarray = JSONArray.fromObject(list);

		return jsonarray.toString();
	}