反序列化里面就多个项目的JSON对象 [英] deserializing a JSON object with multiple items inside it
问题描述
我想反序列化（使用GSON）一个JSON对象，看起来像这样：
附件：{
40：{
ID：40，
URL：HTTP：\ / \ / drewmore4.files.word press.com \ / 2013 \ / 02 \ /wreckit.jpg
GUID：HTTP：\ / \ / drewmore4.files.word press.com \ / 2013 \ / 02 \ /wreckit.jpg
MIME_TYPE：影像\ / JPEG，
宽：287，
高度：400
}，
3：{
ID：3，
URL：HTTP：\ / \ / drewmore4.files.word press.com \ / 2013 \ / 02 \ /frankenweenie2bposter.jpg
GUID：HTTP：\ / \ / drewmore4.files.word press.com \ / 2013 \ / 02 \ /frankenweenie2bposter.jpg
MIME_TYPE：影像\ / JPEG，
宽：273，
高度：400
}
}，
我要如何处理呢？我甚至不知道叫这就是 - 有多个项目再在这里psented $ P $，但它不是一个数组。当我尝试反序列化作为一个数组，程序崩溃的一个预期Begin_Array却发现Begin_Object异常。当我尝试反序列化作为一个强有力的对象（见下面类），该程序运行，但该领域的所有返回null。
下面是类我试图把它映射到：
类附件{
INT ID;
字符串的URL;
}
完整的JSON文件可以看到的这里：
编辑：解决。
@感知的解决方案基本工作。它很复杂，其实，这个元素（还是想知道这是什么多次入境/非数组JSON元）嵌入在确实包含数组较大的JSON对象。同样，这JSON是不是我的设计 - 它来自字preSS REST API，以及（如@Perception提到），我觉得我有这个问题说明了设计缺陷在里面 - 即附件元素应的阵列，而不是一个对象。尽管如此，
不过，如果任何人以往任何时候都需要反序列化使用该API的一个特定网站的所有帖子的查询结果，并进一步需要访问该附件上的每个岗位，这里是你如何做到这一点：
私有类GETALL扩展的AsyncTask＆LT;虚空，虚空，JSONObject的＆GT; {
私有静态最后字符串URL =HTTPS：//public-api.word$p$pss.com/rest/v1/sites/drewmore4.word$p$pss.com/posts/;
@覆盖
受保护的JSONObject doInBackground（空... PARAMS）{
HttpClient的HttpClient的=新DefaultHttpClient（）;
HTTPGET HTTPGET =新HTTPGET（URL）;
httpget.addHeader（接受，应用/ JSON）;
JSONObject的返回=新的JSONObject（）;
HTT presponse响应;
尝试 {
响应= httpclient.execute（HTTPGET）;
HttpEntity实体= response.getEntity（）;
如果（实体！= NULL）{
InputStream的河道= entity.getContent（）;
字符串结果= convertStreamToString（河道）;
返回=新的JSONObject的（结果）;
instream.close（）;
}
}
赶上（ClientProtocolException | IOException异常| JSONException E）{e.printStackTrace（）;}
返回返回;
}
@覆盖
保护无效onPostExecute（JSONObject的返回）{
GSON GSON =新GSON（）;
//帖子是的JSONObject中的元素，是后期对象的数组
尝试 {
JSONArray帖= returned.getJSONArray（上岗）;
为（中间体CURR = 0; CURR＆其中; posts.length（）; CURR ++）{
字符串s = posts.get（CURR）的ToString（）;
第二十一条= gson.fromJson（S，Article.class）;
JSONObject的附件=新的JSONObject（S）.getJSONObject（附件）;
最后的迭代器＆LT;字符串＆GT;键= attachments.keys（）;
而（keys.hasNext（））{
最终的字符串键= keys.next（）;
a.attached.add（gson.fromJson（attachments.getJSONObject（密钥）的ToString（），Attachment.class））;
}
stories.add（一）;
}
}赶上（JSONException E）{
// TODO自动生成的catch块
e.printStackTrace（）;
}
这是数据的一个例子，可能的的应该的已序列化为一个数组，但没有。一种解决方案来分析它是利用的JSONObject 直接
字符串JSON = ...;
最后GSON GSON =新GSON（）;
最后的名单，其中，附件＆GT; attachements =新的ArrayList＆LT;附件＆GT;（64）;
最后的JSONObject jsonObj =新的JSONObject（JSON）.getJSONObject（附件）;
最后的迭代器＆LT;字符串＆GT;键= jsonObj.keys（）;
而（keys.hasNext（））{
最终的字符串键= keys.next（）;
attachements.add（gson.fromJson（jsonObj.getJSONObject（密钥）的ToString（），Attachment.class）;
}
//做些什么attachements
数据的的可以的也可以看作对ID的一张地图，为附件。它可以被反序列化，例如：
最后弦乐jsonObj =新的JSONObject（JSON）.getJSONObject（附件）;
最后GSON GSON =新GSON（）;
最终的地图＆LT;字符串，附件＆GT;数据= gson.fromJson（jsonObj.toString（）
新TypeToken＆LT;地图＆LT;字符串，附件＆GT;＆GT;（）{
} .getType（））;
最后的名单，其中，附件＆GT;附件=新的ArrayList＆LT;附件＆GT;（data.values（））;
这是实际工作
I'm trying to deserialize (using gson) a JSON object that looks like this:
"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
}
},
How do I handle it? I don't even know what to call this - There are multiple "items" represented here, but it's not an array. When I try to deserialize it as an array, the program crashes on a "Expected Begin_Array but found Begin_Object" exception. When I try to deserialize it as a Strong object (see class below), the program runs but the fields all return null.
Here is the class I've tried to map it to:
class Attachment {
int ID;
String URL;
}
the full JSON file can be seen here:
EDIT: SOLVED.
@Perception's solution basically worked. It was complicated by the fact that this "element" (still would like to know what this multiple-entry/non-array json element) is embedded in a larger json object that does contain an array. Again, this JSON is not my design - it comes from the Wordpress REST API, and (as @Perception alluded to), I think the issue I've had illustrates a design flaw in it - namely that the attachments element should be an array, rather than a single object. Nonetheless,
Nonetheless, if anyone else ever needs to deserialize the result of a query for all posts on a given site using this API, and further needs access to the attachments on each post, here's how you do it:
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();
}
This is an example of data that probably should have been serialized as an array, but was not. One solution to parsing it is to utilize a JSONObject directly.
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
The data can also be viewed as a map, of id's to attachments. And it can be deserialized as such:
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());
This is actuall
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