使用Gson库解析Facebook Json对象

Question

I have been working around to parse the JSON objects returned by Facebook. One of the libraries which I relied on is Gson. The aim was to fill a ListView created in an android app with user's photos found in his profile under the photos of you section. Therefore, I have used the following Command:

GraphRequest request = new GraphRequest(AccessToken.getCurrentAccessToken(), "/" + profile.getId() +     "/photos", null,
                    HttpMethod.GET, new GraphRequest.Callback() {

            @Override
            public void onCompleted(GraphResponse response) {
                jsonObject = response.getJSONObject();
                Log.d("JSON", "response is returned");
                communicator.openFragment(jsonObject);
            }
        }
        );
        // This is how to use the fields
        Bundle parameters = new Bundle();
        parameters.putString("fields", "images");
        request.setParameters(parameters);
        request.executeAsync();

The JSON Object was sent to the Main activity of the application was going to send the same JSON Object into another Fragment. My problem comes with parsing the JSON Object .

I have used 2 classes for this purpose: one of which is a Response class Here is the code:

public class Response {

private PagingEntity paging;

private List<DataEntity> data;

public Response() {

}

public void setPaging(PagingEntity paging) {
    this.paging = paging;
}

public void setData(List<DataEntity> data) {
    this.data = data;
}

public PagingEntity getPaging() {
    return paging;
}

public List<DataEntity> getData() {
    return data;
}

public static class PagingEntity {

    private CursorsEntity cursors;
    private String next;

    public void setCursors(CursorsEntity cursors) {
        this.cursors = cursors;
    }

    public void setNext(String next) {
        this.next = next;
    }

    public CursorsEntity getCursors() {
        return cursors;
    }

    public String getNext() {
        return next;
    }

    public static class CursorsEntity {
        private String after;
        private String before;

        public void setAfter(String after) {
            this.after = after;
        }

        public void setBefore(String before) {
            this.before = before;
        }

        public String getAfter() {
            return after;
        }

        public String getBefore() {
            return before;
        }
    }
}

public static class DataEntity {
    private String id;

    private List<ImagesEntity> images;

    public void setId(String id) {
        this.id = id;
    }

    public void setImages(List<ImagesEntity> images) {
        this.images = images;
    }

    public String getId() {
        return id;
    }

    public List<ImagesEntity> getImages() {
        return images;
    }

    public static class ImagesEntity {
        private String source;
        private int width;
        private int height;

        public void setSource(String source) {
            this.source = source;
        }

        public void setWidth(int width) {
            this.width = width;
        }

        public void setHeight(int height) {
            this.height = height;
        }

        public String getSource() {
            return source;
        }

        public int getWidth() {
            return width;
        }

        public int getHeight() {
            return height;
        }
    }
}
}

The CustomAdapter that uses this class is as follows:

public class CustomAdapter extends BaseAdapter{
private List<Response.DataEntity> dataEntityList;
private Context context;

public CustomAdapter(Context context, List<Response.DataEntity> dataEntityList) {
    this.context = context;
    this.dataEntityList = dataEntityList;
}

@Override
public int getCount() {
    return dataEntityList.size();
}

@Override
public Object getItem(int position) {
    return dataEntityList.get(position);
}

@Override
public long getItemId(int position) {
    return 0;
}

public Object getImage(int imageSet) {
    return dataEntityList.get(imageSet).getImages()
            .get(dataEntityList.get(imageSet).getImages().size() - 1);
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    View rowView = inflater.inflate(R.layout.each_item_list, parent, false);

    ImageView thumbnail = (ImageView) rowView.findViewById(R.id.thumbnail);
    TextView height = (TextView) rowView.findViewById(R.id.height);
    TextView width = (TextView) rowView.findViewById(R.id.width);

    Response.DataEntity.ImagesEntity item = (Response.DataEntity.ImagesEntity) getImage(position);
    String imageURL = item.getSource();

    Picasso.with(context).load(imageURL).into(thumbnail);
    height.setText(item.getHeight() + "");
    width.setText(item.getWidth() + "");

    return rowView;
}
}

Therfore, I was able in the parse the JSON object and extract the URLs of the images, but I don't know how get the rest of the images because of the pagination features in the returned JSON Objects by facebook. The code for parsing is as follows: ( This was added in the onCreateView in the fragment )

gson = new Gson();
    String jsonFetched = jsonObject.toString();
    String jsonToPass = jsonFetched.replace("\\/", "/");
    response = gson.fromJson(jsonToPass, Response.class);
    adapter = new CustomAdapter(getActivity().getBaseContext(),    response.getData());
    listView.setAdapter(adapter);
    return view;

Please help me out how to parse the rest of the JSON Object, that is, automatically going through the "next" tag in the JSON object to get the next JSON Object and parse it and so on

Any Help Much APPRECIATED.... THANKS

Answer 1

To get the rest of the Images, here is my new code:

final GraphRequest.Callback graphCallback = new GraphRequest.Callback(){
        @Override
        public void onCompleted(GraphResponse response) {
                Bundle parameters = new Bundle();
                parameters.putString("fields", "images");
                parameters.putString("limit", "50");
                jsonObject = response.getJSONObject();
                GraphRequest newRequest = response.getRequestForPagedResults(GraphResponse.PagingDirection.NEXT);
                newRequest.setGraphPath("/" + profile.getId() + "/photos");
                newRequest.setCallback(this);
                newRequest.setParameters(parameters);
                newRequest.executeAsync();
        }
    };

Notice that the information found on facebook developers is not enough https://developers.facebook.com/docs/reference/android/current/class/GraphResponse/ Therefore, I have to add the GraphPath, CallBack and bundles parameter.

Finally, This GraphRequest.Call object is to be added the GraphRequest request object as follows:

final GraphRequest request = new GraphRequest(
                AccessToken.getCurrentAccessToken(), "/" + profile.getId() + "/photos", null,
                HttpMethod.GET, graphCallback
        );