reverfit2访问对象的内部数组

Question

我试图从一个Json文件中提取一个对象列表，但是该文件以一个对象开始，该对象包含我需要的对象数组。我是一个新的改造这里是我的文件：接口

public interface OSMApi {

    @Headers({"Accept: application/json"})
    @GET("map")
    Call<List<OSMObject>> getOSMObjects(@Query("bbox") String boxMinMaxLatLon);
}

控制器

public class OSMController implements Callback<List<OSMObject>> {

    static final String BASE_URL = "https://api.openstreetmap.org/api/0.6/";
    private static final String TAG = "OSMController";

    private String bboxLatLon = "//latlongshere";

    public void start(){
        Gson gson = new GsonBuilder()
                .setLenient()
                .create();

    Retrofit retrofit = new Retrofit.Builder()
            .baseUrl(BASE_URL)
            .addConverterFactory(GsonConverterFactory.create(gson))
            .build();

    OSMApi osmApi = retrofit.create(OSMApi.class);

    Call<List<OSMObject>> call = osmApi.getOSMNodes(bboxLatLon);
    call.enqueue(this);
}

    @Override
    public void onResponse(Call<List<OSMObject>> call, Response<List<OSMObject>> response) {
        if(response.isSuccessful()){
            List<OSMObject> OSMObjectList = response.body();
            OSMObjectList.forEach(OSMObject -> Log.d(TAG, "onResponse: objects "+OSMObject.getId()));
        }else{
            Log.d(TAG, "onResponse: here : "+response.errorBody() + ", "+response.code());
        }
    }

    @Override
    public void onFailure(Call<List<OSMObject>> call, Throwable t) {
        Log.d(TAG, "onFailure: "+ t.getStackTrace() + ", extra: "+ t.getMessage());
    }
}

Json的开头

{
    "version": "0.6",
    "generator": "CGImap 0.8.3 (652902 spike-07.openstreetmap.org)",
    "copyright": "OpenStreetMap and contributors",
    "attribution": "http://www.openstreetmap.org/copyright",
    "license": "http://opendatacommons.org/licenses/odbl/1-0/",
    "bounds": {
        "minlat": 1.0,
        "minlon": 1.0,
        "maxlat": 1.0,
        "maxlon": 1.0
    },
    "elements": [
        {
            "type": "node",
            "id": 443479273,
            "lat": 1.0,
            "lon": 1.0,
            "timestamp": "2011-04-11T18:06:02Z",
            "version": 3,
            "changeset": 4435725,
            "user": "BeerOfTheTrip",
            "uid": 440880
        },
        {
            "type": "node",
            "id": 443479278,
            "lat": 1.0,
            "lon": 1.0,
            "timestamp": "2011-04-11T18:06:01Z",
            "version": 2,
            "changeset": 4435725,
            "user": "BeerOfTheTrip",
            "uid": 440880
        },
        {
            "type": "node",
            "id": 443479281,
            "lat": 1.0,
            "lon": 1.0,
            "timestamp": "2011-04-11T18:06:01Z",
            "version": 2,
            "changeset": 4435725,
            "user": "BeerOfTheTrip",
            "uid": 440880
        },
etc..........

我的对象Pojo

public class OSMObject implements SerializedName {

    @SerializedName("type")
    @Expose
    private String type;
    @SerializedName("id")
    @Expose
    private int id;
    @SerializedName("lat")
    @Expose
    private double lat;
    @SerializedName("lon")
    @Expose
    private double lon;
    @SerializedName("timestamp")
    @Expose
    private String timestamp;
    @SerializedName("version")
    @Expose
    private int version;
    @SerializedName("changeset")
    @Expose
    private int changeset;
    @SerializedName("uid")
    @Expose
    private int uid;
    @SerializedName("nodes")
    @Expose
    private int[] nodes;

    //Separation
    private ArrayList<OSMNode> OSMNodes = new ArrayList<>();
    private ArrayList<OSMWay> OSMWays = new ArrayList<>();

    public OSMObject(String type, int id, String timestamp, int version, int changeset, int uid, int[] nodes) {
        this.type = type;
        this.id = id;
        this.timestamp = timestamp;
        this.version = version;
        this.changeset = changeset;
        this.uid = uid;
        this.nodes = nodes;
    }

    public OSMObject(String type, int id, double lat, double lon, String timestamp, int version, int changeset, int uid) {
        this.type = type;
        this.id = id;
        this.lat = lat;
        this.lon = lon;
        this.timestamp = timestamp;
        this.version = version;
        this.changeset = changeset;
        this.uid = uid;
    }

+getters and setters....

所以我不需要jsonObject中的任何初始信息，我所需要的只是元素jsonArray中的对象列表，它由两个稍微不同的对象组成，一个有nodes[]，一个没有。因此POJO中有2个构造函数？

我如何设置改装来处理这件事？与当前一样，我在失败时得到的错误是：

onFailure:[Ljava.lang.StackTraceElement；@DBE860F,Extra：应为BEGIN_ARRAY,但在第1行第2列路径$处为BEGIN_OBJECT

附加：两个不同对象的示例：

        {
            "type": "node",
            "id": 4448646916,
            "lat": 1.0,
            "lon": 1.0,
            "timestamp": "2020-12-21T17:52:35Z",
            "version": 1,
            "changeset": 44211151,
            "user": "Mike Greenwood",
            "uid": 44623152
        },
        {
            "type": "way",
            "id": 44117969,
            "timestamp": "2014-04-11T14:01:16Z",
            "version": 2,
            "changeset": 44627679,
            "user": "Smurfy12",
            "uid": 44220096,
            "nodes": [
                4483345702,
                443479293,
                443479273
            ],
            "tags": {
                "highway": "residential",
                "name": "A Street"
            }
        },

正如您所看到的，它们是不同的“类型”一个“节点”和一个“方式”方式有一个节点数组，而节点有一个“lat”和“lon”我现在不需要担心“标签”。

Answer 1

在“onresponse”中，尝试以下操作：

    if (response.isSuccessful()) {

        JSONObject reader = new JSONObject(response.body());

        List<OSMObject> OSMObjectList = (List<OSMObject>) reader.getJSONArray("elements");

        // now you can work on your "elements" list..

    } else {
        Log.d(TAG, "onResponse: here : " + response.errorBody() + ", " + response.code());
    }

注意：关于两个构造函数--我不确定你如何区分你需要使用哪一个构造函数的区别，因为在你的“元素”数组中只有3个相似的对象，所以如果你需要帮助--请解释一下区别是什么，或者给出你可能在那个数组中收到的另一个对象的例子。