小编典典

反序列化带有多个项目的JSON对象

json

我正在尝试反序列化(使用gson)如下所示的JSON对象:

        "attachments": {
            "40": {
                "ID": 40,
                "URL": "http:\/\/drewmore4.files.wordpress.com\/2013\/02\/wreckit.jpg",
                "guid": "http:\/\/drewmore4.files.wordpress.com\/2013\/02\/wreckit.jpg",
                "mime_type": "image\/jpeg",
                "width": 287,
                "height": 400
            },
            "3": {
                "ID": 3,
                "URL": "http:\/\/drewmore4.files.wordpress.com\/2013\/02\/frankenweenie2bposter.jpg",
                "guid": "http:\/\/drewmore4.files.wordpress.com\/2013\/02\/frankenweenie2bposter.jpg",
                "mime_type": "image\/jpeg",
                "width": 273,
                "height": 400
            }
    },

我该如何处理?我什至不知道该怎么称呼-
这里代表了多个“项目”,但这不是一个数组。当我尝试将其反序列化为数组时,程序在“预期的Begin_Array但找到Begin_Object”异常时崩溃。当我尝试将其反序列化为Strong对象时(请参见下面的类),程序将运行,但所有字段均返回null。

这是我尝试将其映射到的类:

class Attachment {
int ID;
String URL;
}

完整的JSON文件可以在这里看到

编辑:已解决。

@Perception的解决方案基本有效。这个“元素”(仍然想知道这个多入口/非数组json元素是什么)被嵌入在一个确实包含数组的更大的json对象中的事实使情况变得复杂。再说一次,这个JSON不是我设计的-
它来自Wordpress REST API,并且(正如@Perception所暗示的那样),我认为我遇到的问题说明了它的设计缺陷-
也就是说,attachments元素应该是一个数组,而不是单个对象。尽管如此,

但是,如果其他任何人需要使用此API对给定站点上所有帖子的查询结果进行反序列化,并且进一步需要访问每个帖子的附件,请按以下步骤操作:

  private class getAll extends AsyncTask <Void, Void, JSONObject> {
    private static final String url = "https://public-api.wordpress.com/rest/v1/sites/drewmore4.wordpress.com/posts/";
    @Override
    protected JSONObject doInBackground(Void... params) {

        HttpClient httpclient = new DefaultHttpClient();
        HttpGet httpget = new HttpGet(url);
        httpget.addHeader("accept", "application/json");
        JSONObject returned = new JSONObject();
        HttpResponse response;

        try {
            response = httpclient.execute(httpget);
            HttpEntity entity = response.getEntity();

            if (entity != null) {
                InputStream instream = entity.getContent();
                String result= convertStreamToString(instream);

                returned =new JSONObject(result);                   
                instream.close();
            }
        } 
        catch (ClientProtocolException | IOException | JSONException e) { e.printStackTrace();}

        return returned;
    }

        @Override
    protected void onPostExecute (JSONObject returned){
        Gson gson = new Gson();

//posts is the element within the JSONObject that is an array of post objects
        try {
        JSONArray posts = returned.getJSONArray("posts");

        for (int curr = 0; curr < posts.length(); curr++){
            String s = posts.get(curr).toString();

            Article a = gson.fromJson(s, Article.class);

            JSONObject attachments = new JSONObject(s).getJSONObject("attachments");
            final Iterator<String> keys = attachments.keys();
               while(keys.hasNext()) {
                    final String key = keys.next();
                    a.attached.add(gson.fromJson(attachments.getJSONObject(key).toString(), Attachment.class));
                }   
               stories.add(a);
        }

            } catch (JSONException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

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2020-07-27

共1个答案

小编典典

这是一个数据示例,可能 应该 已经序列化为数组,但是没有被序列化。解析它的一种解决方案是JSONObject直接利用Direct。

String json = ...;
final Gson gson = new Gson();

final List<Attachment> attachements = new ArrayList<Attachment>(64);
final JSONObject jsonObj = new JSONObject(json).getJSONObject("attachments");
final Iterator<String> keys = jsonObj.keys();
while(keys.hasNext()) {
    final String key = keys.next();
    attachements.add(gson.fromJson(jsonObj.getJSONObject(key).toString(), Attachment.class);
}

// Do something with attachements

该数据 也被看作是一个地图,ID的对附件。可以这样反序列化:

final String jsonObj = new JSONObject(json).getJSONObject("attachments");
final Gson gson = new Gson();
final Map<String, Attachment> data = gson.fromJson(jsonObj.toString(),
        new TypeToken<Map<String, Attachment>>() {
        }.getType());
final List<Attachment> attachments = new ArrayList<Attachment>(data.values());

这是实际的

2020-07-27