java - 如何从java中的json响应中获取数组

Question

我正在使用 instagram REST api，我需要从 JSON 响应中获取图像链接。

JSON 看起来类似于:

{
    "meta":
    {
        "code": 200
    },
    "data":
    {
        "attribution": null,
        "tags":
        [
            "tag"
        ],
        "type": "image",
        "location": null,
        "comments":
        {
            "count": 7
        },
        "filter": "Normal",
        "created_time": "1451066377",
        "link": "https://www.instagram.com/p/at3rg7uj_9/",
        "likes":
        {
            "count": 39
        },
        "images":
        {
            "low_resolution":
            {
                "url": "https://url.jpg",
                "width": 320,
                "height": 320
            },
            "thumbnail":
            {
                "url": "https://url.jpg",
                "width": 150,
                "height": 150
            },
            "standard_resolution":
            {
                "url": "https://url.jpg?ig_cache_key=key",
                "width": 640,
                "height": 640
            }
        },
        "users_in_photo":
        [
        ],
        "caption":
        {
            "created_time": "1451066377",
            "text": "caption",
            "from":
            {
                "username": "f",
                "profile_picture": "https://profilepic.jpg",
                "id": "185333924",
                "full_name": "name"
            },
            "id": "17852020759022520"
        },
        "user_has_liked": false,
        "id": "1147950432085956322_185333924",
        "user":
        {
            "username": "",
            "profile_picture": "https://prifilepic.jpg",
            "id": "185333924",
            "full_name": "name"
        }
    }
}

我如何在 java 中引用“图像”对象？

我试过这个:

JSONObject object = (JSONObject) new JSONTokener(s).nextValue();
JSONObject images = object.getJSONObject("images");
JSONObject image = images.getJSONObject("standard_resolution");
String url = image.getString("url");

还有这个:

JSONObject object = (JSONObject) new JSONTokener(s).nextValue();
JSONArray images = object.getJSONArray("images");
JSONObject standardRes = images.getJSONObject(2);
String url = standardRes.getString("url");

S 是保存为字符串的 JSON 响应，如下所示:

try {
        URL url = new URL(link);
        HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
        try {
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(urlConnection.getInputStream()));
            StringBuilder stringBuilder = new StringBuilder();
            String line;
            while ((line = bufferedReader.readLine()) != null) {
                stringBuilder.append(line).append("\n");
            }
            bufferedReader.close();
            return stringBuilder.toString(); // s
        } finally {
            urlConnection.disconnect();
        }
    } catch (Exception e) {
        Log.e("ERROR", e.getMessage(), e);
        return null;
    }

但在这两种情况下，我都会收到“无图像值(value)”错误。

Answer 1

images 嵌套在 data

中

JSONObject object = (JSONObject) new JSONTokener(s).nextValue();
JSONObject data = object.getJSONObject("data");
JSONObject images = data.getJSONObject("images");
...