getJSONObject与optJSONObject的区别,结合源码分析

*json解析常见问题:

• getJSONObject与optJSONObject的区别,下面结合源码和案例来分析当我们使用这两周方法来解析数据时,哪种比较好.

• 源码分析:

//使用getJSONObject时,如果返回的对象不是JSONObject,抛出JSONException异常
   /** * Returns the value mapped by {@code name} if it exists and is a {@code * JSONObject}. * @throws JSONException if the mapping doesn't exist or is not a {@code * JSONObject}. */

    public JSONObject getJSONObject(String name) throws JSONException {
        Object object = get(name);
        if (object instanceof JSONObject) {
            return (JSONObject) object;
        } else {
            throw JSON.typeMismatch(name, object, "JSONObject");
        }
    }



//使用optJSONObject时,当返回结果不是JSONObject时,这里不会抛异常,而是返回null
    /** * Returns the value mapped by {@code name} if it exists and is a {@code * JSONObject}. Returns null otherwise. */
    public JSONObject optJSONObject(String name) {
        Object object = opt(name);
        return object instanceof JSONObject ? (JSONObject) object : null;
    }

• 结合项目代码分析使用场景

   /** * 伪代码如下 **/
    public class GetGoodsCollectListFactory {
        private String ERROR_MSG  = "errorMsg";
        private String ERROR_CODE = "errorCode";
        private String RESULT     = "result";

        /** * 商品列表,解析获取到的json数据 * * @param param * @return */
        public CollectListInfo getGoodsCollectListParse(String param) {
            String BOOK_MARK_BO_LIST = "favorGoodsList";
            CollectListInfo collectList = new CollectListInfo();
            List<CollectInfo> list = new ArrayList<CollectInfo>();
            ResponseInfo responseInfo = null;
            CollectInfo info = null;
            try {
                // 请求获取json结果
                JSONObject jsonObject = new JSONObject(HttpRequestClient.executeRequest(Constant.Url.GET_FOLLOW_GOODS_URL, param, true));
                responseInfo = new ResponseInfo();
                if (jsonObject.getBoolean(RESULT)) {
                    responseInfo.setResult(true);
                    JSONArray jsonArray = jsonObject.getJSONArray(BOOK_MARK_BO_LIST);
                    collectList.setTotalPage(jsonObject.getInt(Constant.TOTAL_PAGE_NAME));
                    for (int i = 0; i < jsonArray.length(); i++) {
                        info = collectList.getCollectInfo();
                        SONObject object = jsonArray.getJSONObject(i);
                        JSONArray activityItemList = object.optJSONArray("activityItemList");
                        ArrayList<ActivityCollectInfo> activityCollectInfos = new ArrayList<ActivityCollectInfo>();

                        //因为object.optJSONArray("activityItemList");如果解析不到会直接返null
                        if (activityItemList != null && activityItemList.size() > 0) {
                            for (int j = 0; j < activityItemList.length(); j++) {

                                //使用optJSONObject(i)会莫名解析不了下面数据:如optString("activityId"));
                                // 当activityid为null时,不会抛错,但是下面的方法不走,因此换用getJSONObject(i);
                                //JSONObject activityItemobj = activityItemList.optJSONObject(i);

                                JSONObject activityItemobj = activityItemList.getJSONObject(i);
                                ActivityCollectInfo activityCollectInfo = new ActivityCollectInfo();
                                activityCollectInfo.setActivityId(activityItemobj.optString("activityId"));
                                activityCollectInfo.setActivityName(activityItemobj.optString("activityName"));
                                activityCollectInfo.setActivityType(activityItemobj.optInt("activityType"));
                                activityCollectInfo.setLargessFlag(activityItemobj.optInt("largessFlag"));
                                activityCollectInfo.setLargessMoney(activityItemobj.optInt("largessMoney"));
                                activityCollectInfo.setLargessNumber(activityItemobj.optInt("largessNumber"));
                                activityCollectInfos.add(activityCollectInfo);
                            }
 ...                       
                        }
                }

温故而知新，可以为师矣.