Android getJSONObject与optJSONObject的区别结合源码分析

Android 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 list = new ArrayList();
      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 activityCollectInfos = new ArrayList();

            //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.