改装分页不会加载新商品

Question

我有一个API响应，我需要在listView上显示。一开始它以15个项目开始，我想在用户向下滚动并到达列表末尾时添加更多项目。使用Retrofit自动翻页API的最佳策略是什么，以便默认下载所有可用数据？分页有效，但我不认为是从下一个URL加载新数据，而是重新加载旧数据。 请帮忙！任何帮助将不胜感激。

这些是我需要使用的响应中的参数： 显然我没有以正确的方式使用它们。

"total": 181,
    "per_page": "15",
    "current_page": 1,
    "last_page": 13,
    "next_page_url": "URL",
    "prev_page_url": null,
    "from": 1,
    "to": 15,

主：

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl("http://nmc.no-ip.org:8888/")
                .addConverterFactory(GsonConverterFactory.create())
                .build();


        StreamingOfferService service = retrofit.create(StreamingOfferService.class);
        Call<ResponseResult> response = service.getStreamingOffers();


        response.enqueue(new Callback<ResponseResult>() {
            @Override
            public void onResponse(Call<ResponseResult> result, Response<ResponseResult> response) {
                createList(response);
            }

            @Override
            public void onFailure(Call<ResponseResult> result, Throwable t) {

            }


        });

    }

    public void createList(final Response<ResponseResult> response)

    {

        final ListView listview = (ListView) findViewById(R.id.listview);
        final StreamingAdapter adapter = new StreamingAdapter(this,R.layout.listofusers,response);
        listview.setAdapter(adapter);
        listview.setOnScrollListener(new AbsListView.OnScrollListener() {


            @Override
            public void onScrollStateChanged(AbsListView view, int scrollState) {


            }

            @Override
            public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {

                ResponseResult r = new ResponseResult();
                int currentPageNumber = r.getCurrentPage();
                boolean loading = true;
               // String next_page_url = r.getNextPageUrl();

                if (listview.getLastVisiblePosition() == listview.getAdapter().getCount() - 1
                        && listview.getChildAt(listview.getChildCount() - 1).getBottom() <= listview.getHeight()) {
                        r.getNextPageUrl();
                        currentPageNumber++;

                    loading = true;
                    Retrofit retrofit = new Retrofit.Builder()
                            .baseUrl("http://nmc.no-ip.org:8888/")
                            .addConverterFactory(GsonConverterFactory.create())
                            .build();

                    StreamingOfferService service = retrofit.create(StreamingOfferService.class);
                    Call<ResponseResult> response = service.getStreamingOffers();

                    response.enqueue(new Callback<ResponseResult>() {
                        @Override
                        public void onResponse(Call<ResponseResult> result, Response<ResponseResult> response) {
                            adapter.addToList(response);
                        }

                        @Override
                        public void onFailure(Call<ResponseResult> result, Throwable t) {

                        }
                    });
                }}
        });
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        int id = item.getItemId();


        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

适配器：

public class StreamingAdapter extends BaseAdapter {

    private Context context;
    private int resource;
    private LayoutInflater inflater;
    private List<StreamingOffer> streamingOfferList;





    public StreamingAdapter(Context context, int resource, Response<ResponseResult> response) {
        this.context=context;
        this.resource=resource;
        this.inflater=LayoutInflater.from(context);
        streamingOfferList = response.body().getData();

    }

    void addToList(Response<ResponseResult> response)
    {

        this.streamingOfferList.addAll(streamingOfferList);
        this.notifyDataSetChanged();
    }


    public class Holder extends User {

        private TextView full_name;
        private TextView location;
        private TextView price;
        private TextView currency_symbol;
        private TextView total_streamed;

        private  ImageView offer;
        private  ImageView profile;
        private  ImageView iconUser;
        private  ImageView iconStar;
        private  ImageView iconStar1;
        private  ImageView iconStar2;
        private  ImageView iconStar3;
        private  ImageView iconStar4;

    }



    @Override
    public View getView(int position, View convertView, ViewGroup parent) {

        Holder holder = new Holder();
        View itemView = convertView;

        StreamingOffer streamingOffer = getItem(position);
        User u = streamingOffer.getUser();

        if(itemView==null) {
            itemView = inflater.inflate(resource, parent, false);

            holder.full_name = (TextView) itemView.findViewById(R.id.full_name);
            holder.full_name.setText(u.getFullName());

            holder.location = (TextView) itemView.findViewById(R.id.location);
            holder.location.setText(streamingOffer.getLocation());


            holder.price = (TextView) itemView.findViewById(R.id.price);
            holder.currency_symbol = (TextView) itemView.findViewById(R.id.currency_symbol);

            if(streamingOffer.getIs_free()==0)
            {
                holder.price.setText(streamingOffer.getPrice());
                holder.currency_symbol.setText(streamingOffer.getCurrencySymbol());
            }
            else
                holder.price.setText("FREE");


            holder.total_streamed = (TextView) itemView.findViewById(R.id.total_streamed);
            holder.total_streamed.setText(u.getTotalStreamed());

            holder.offer = (ImageView) itemView.findViewById(R.id.offer);
            holder.profile = (ImageView) itemView.findViewById(R.id.profile);
            holder.iconUser = (ImageView) itemView.findViewById(R.id.iconUser);
            holder.iconStar = (ImageView) itemView.findViewById(R.id.iconStar);
            holder.iconStar1 = (ImageView) itemView.findViewById(R.id.iconStar1);
            holder.iconStar2 = (ImageView) itemView.findViewById(R.id.iconStar2);
            holder.iconStar3 = (ImageView) itemView.findViewById(R.id.iconStar3);
            holder.iconStar4 = (ImageView) itemView.findViewById(R.id.iconStar4);




            Images im = new Images();
            im.getImage_75x75();
            final GsonBuilder builder = new GsonBuilder();
            final Gson gson = builder.create();
            String json = gson.toJson(im);

            if(json.contains("75x75")){
                Picasso.with(context).load(im.getImage_75x75()).into(holder.profile);

            }


           //Picasso.with(context).load(jsonRepresentation).into(holder.offer);
            Picasso.with(context).load(im.getImage_154x154()).into(holder.profile);
            Picasso.with(context).load(im.getImage_154x154()).into(holder.offer);


            Picasso.with(context)
                    .load(R.drawable.icon_red_star).into(holder.iconStar);
            Picasso.with(context)
                    .load(R.drawable.half_red_star).into(holder.iconStar1);
            Picasso.with(context)
                    .load(R.drawable.icon_black_star).into(holder.iconStar2);
            Picasso.with(context)
                    .load(R.drawable.icon_black_star).into(holder.iconStar3);
            Picasso.with(context)
                    .load(R.drawable.icon_black_star).into(holder.iconStar4);

           // Picasso.with(context)
           //         .load("http://nmc.no-ip.org:8888/assets/images/offer-2.png").into(holder.offer);
           // Picasso.with(context)
             //       .load("http://nmc.no-ip.org:8888/assets/images/profile-1.png").into(holder.profile);


            if(u.getIs_online()==1) {
                Picasso.with(context)
                        .load(R.drawable.icon_user_online).into(holder.iconUser);
            }
            else
                Picasso.with(context)
                        .load(R.drawable.icon_user_offline).into(holder.iconUser);}




            if(u.getRating()!=null) {
                if (u.getRating() == "1.0" && u.getRating() == "1.5") {
                    Picasso.with(context)
                            .load(R.drawable.icon_red_star).into(holder.iconStar);
                    Picasso.with(context)
                            .load(R.drawable.icon_black_star).into(holder.iconStar1);
                    Picasso.with(context)
                            .load(R.drawable.icon_black_star).into(holder.iconStar2);
                    Picasso.with(context)
                            .load(R.drawable.icon_black_star).into(holder.iconStar3);
                    Picasso.with(context)
                            .load(R.drawable.icon_black_star).into(holder.iconStar4);

                }

                if (u.getRating() == "2.0" && u.getRating() == "2.5") {
                    Picasso.with(context)
                            .load(R.drawable.icon_red_star).into(holder.iconStar);
                    Picasso.with(context)
                            .load(R.drawable.icon_red_star).into(holder.iconStar1);
                    Picasso.with(context)
                            .load(R.drawable.icon_black_star).into(holder.iconStar2);
                    Picasso.with(context)
                            .load(R.drawable.icon_black_star).into(holder.iconStar3);
                    Picasso.with(context)
                            .load(R.drawable.icon_black_star).into(holder.iconStar4);

                }
                if (u.getRating() == "3.0" && u.getRating() == "3.5") {
                    Picasso.with(context)
                            .load(R.drawable.icon_red_star).into(holder.iconStar);
                    Picasso.with(context)
                            .load(R.drawable.icon_red_star).into(holder.iconStar1);
                    Picasso.with(context)
                            .load(R.drawable.icon_red_star).into(holder.iconStar2);
                    Picasso.with(context)
                            .load(R.drawable.icon_black_star).into(holder.iconStar3);
                    Picasso.with(context)
                            .load(R.drawable.icon_black_star).into(holder.iconStar4);

                }
                if (u.getRating() == "4.0" && u.getRating() == "4.5") {
                    Picasso.with(context)
                            .load(R.drawable.icon_red_star).into(holder.iconStar);
                    Picasso.with(context)
                            .load(R.drawable.icon_red_star).into(holder.iconStar1);
                    Picasso.with(context)
                            .load(R.drawable.icon_red_star).into(holder.iconStar2);
                    Picasso.with(context)
                            .load(R.drawable.icon_red_star).into(holder.iconStar3);
                    Picasso.with(context)
                            .load(R.drawable.icon_black_star).into(holder.iconStar4);

                }
                if (u.getRating() == "5.0") {
                    Picasso.with(context)
                            .load(R.drawable.icon_red_star).into(holder.iconStar);
                    Picasso.with(context)
                            .load(R.drawable.icon_red_star).into(holder.iconStar1);
                    Picasso.with(context)
                            .load(R.drawable.icon_red_star).into(holder.iconStar2);
                    Picasso.with(context)
                            .load(R.drawable.icon_red_star).into(holder.iconStar3);
                    Picasso.with(context)
                            .load(R.drawable.icon_red_star).into(holder.iconStar4);

                }
            }

        itemView.setTag(holder);
        return itemView;
    }


    @Override
    public int getCount() {

        return streamingOfferList.size();
    }

    @Override
    public StreamingOffer getItem(int position) {
        return streamingOfferList.get(position);
    }

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



}