android studio_Android getJSONObject与optJSONObject的区别结合源码分析

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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}.

   */

  publicJSONObject getJSONObject(String name)throwsJSONException {

    Object object = get(name);

    if(objectinstanceofJSONObject) {

      return(JSONObject) object;

    }else{

      throwJSON.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.

   */

  publicJSONObject optJSONObject(String name) {

    Object object = opt(name);

    returnobjectinstanceofJSONObject ? (JSONObject) object :null;

  }

结合项目代码分析使用场景

/**

 * 伪代码如下

 **/

 publicclassGetGoodsCollectListFactory {

   privateString ERROR_MSG ="errorMsg";

   privateString ERROR_CODE ="errorCode";

   privateString RESULT   ="result";

   /**

    * 商品列表,解析获取到的json数据

    *

    * @param param

    * @return

    */

   publicCollectListInfo getGoodsCollectListParse(String param) {

     String BOOK_MARK_BO_LIST ="favorGoodsList";

     CollectListInfo collectList =newCollectListInfo();

     Listlist =newArrayList();

     ResponseInfo responseInfo =null;

     CollectInfo info =null;

     try{

       // 请求获取json结果

       JSONObject jsonObject =newJSONObject(HttpRequestClient.executeRequest(Constant.Url.GET_FOLLOW_GOODS_URL, param,true));

       responseInfo =newResponseInfo();

       if(jsonObject.getBoolean(RESULT)) {

         responseInfo.setResult(true);

         JSONArray jsonArray = jsonObject.getJSONArray(BOOK_MARK_BO_LIST);

         collectList.setTotalPage(jsonObject.getInt(Constant.TOTAL_PAGE_NAME));

         for(inti =0; i < jsonArray.length(); i++) {

           info = collectList.getCollectInfo();

           SONObject object = jsonArray.getJSONObject(i);

           JSONArray activityItemList = object.optJSONArray("activityItemList");

           ArrayListactivityCollectInfos =newArrayList();

           //因为object.optJSONArray("activityItemList");如果解析不到会直接返null

           if(activityItemList !=null&& activityItemList.size() >0) {

             for(intj =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 =newActivityCollectInfo();

               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.

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