使用Gson解析json webservice响应（预期为BEGIN_OBJECT，但实际为BEGIN_ARRY)

Question

{
"info": {
    "num_results": 2974,
    "limit": 100,
    "offset": 0,
    "query": "foo",
    "type": "track",
    "page": 1
},
"tracks": [
    {
        "album": {
            "released": "2009",
            "href": "spotify:album:1zCNrbPpz5OLSr6mSpPdKm",
            "name": "Greatest Hits",
            "availability": {
                "territories": "AD AR AT AU BE BG BO BR CA CH CL CO CR CY CZ DE DK DO EC EE ES FI FR GB GR GT HK HN HU IE IS IT LI LT LU LV MC MT MX MY NI NL NO NZ PA PE PH PL PT PY RO SE SG SI SK SV TR TW US UY"
            }
        },
        "name": "Everlong",
        "popularity": "0.79",
        "external-ids": [
            {
                "type": "isrc",
                "id": "USRW29600011"
            }
        ],
        "length": 249.986,
        "href": "spotify:track:07q6QTQXyPRCf7GbLakRPr",
        "artists": [
            {
                "href": "spotify:artist:7jy3rLJdDQY21OgRLCZ9sD",
                "name": "Foo Fighters"
            }
        ],
        "track-number": "3"
    }]
}

JsonParser parser = new JsonParser();
JsonObject jObject = parser.parse(jsonString).getAsJsonObject();
JsonArray jArray = jObject.get("tracks") .getAsJsonArray();


Gson gson = new Gson();
List<Track> trackArr = new ArrayList<Track>();

Type collectiontype = new TypeToken<Collection<Track>>(){}.getType();
Collection<Track> trackColl = gson.fromJson(jArray.toString(), collectiontype);

但是我得到了错误：com.google.gson.jsonSyntaxException:java.lang.IllegalStateException:预期的BEGIN_OBJECT但是是BEGIN_ARRAY

我不明白为什么在尝试获取json字符串中的“tracks”对象whihc是一个数组[]时执行“getasjsonArray（）”，而期望begin object。

'track'的列表是当我在一个循环中执行此操作以将所有的曲目放入一个数组时：

for (JsonElement jsonElement : jArray) {
  Type collectiontype = new TypeToken<Collection<Track>>(){}.getType();
  Collection<Track> trackCol = gson.fromJson(jsonElement, collectiontype);
  trackArr.add((Track) trackCol);

}

Answer 1

您不必使用额外的库来解析JSON文件。还可以使用此链接以人类可读的方式读取JSON文件。

使用本机的，如下例所示：

进口：

import org.json.JSONArray;
import org.json.JSONObject;

JSONObject fileJSONObject = new JSONObject(response);

JSONObject infoJSONObject = fileJSONObject.getJSONObject("info");
JSONArray tracksJSONArray = fileJSONObject.getJSONArray("tracks");

//Parsing the info
String trackType = infoJSONObject.getString("type");
String trackLimit = infoJSONObject.getString("limit");
//The rest of attributes


//Parsing the track list
JSONObject object;
for(int i=0;i<tracksJSONArray.length();i++){
    object = tracksJSONArray.getJSONObject(i);
    String trackName = object.getString("name");
    //The rest of attributes

}