我已经在我的应用程序中实现了分页，但是在增加页面索引方面遇到了麻烦。我正在从unsplash api获取数据，并形成了如下所示的请求网址：
private String url = Constants.SEARCH_URL + "top30&page="+ PAGE_INDEX;
这是下面使用的网址：
https://api.unsplash.com/search/photos?client_id=api_key&order_by=latest&query=top30&page=1
在我的片段中，我有一个常量private static int PAGE_INDEX = 1;，它跟踪当前页面并用于获取下一页直到页面限制。
第一个请求运行正常，当滚动到最后一个项目时，将提取更多项目。但是，这些项与首页索引中的项相同，并且在记录了网址后，我得到的内容与第一个请求中的相同，如下所示：
https://api.unsplash.com/search/photos?client_id=api_key&order_by=latest&query=top30&page=1
我已经将滚动侦听器附加到了recyclerview中，并递增了PAGE_INDEX，但没有获得url中的下一页，但是在log cat中它显示页面索引为2。这是附加的侦听器：
top30RV.addOnScrollListener(new PaginationScrollListener(llm) {
@Override
protected void loadMoreItems() {
isLoading = true;
PAGE_INDEX = PAGE_INDEX + 1;
Log.d(TAG, "PIn:\t" + PAGE_INDEX);
loadNextPage();
}
@Override
protected int getTotalPageCount() {
return PAGE_COUNT;
}
@Override
public boolean isLoading() {
return isLoading;
}
@Override
public boolean isLastPage() {
return isLastPage;
}
});
和我的PaginationScrollListener类代码：
public abstract class PaginationScrollListener extends RecyclerView.OnScrollListener {
LinearLayoutManager llm;
public PaginationScrollListener(LinearLayoutManager llm) {
this.llm = llm;
}
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
int visisbleItemCount = recyclerView.getChildCount();
int totalItemCount = llm.getItemCount();
int firstVisibleItemPosn = llm.findFirstVisibleItemPosition();
if (!isLoading() && !isLastPage()){
if ((visisbleItemCount + firstVisibleItemPosn) >= totalItemCount && firstVisibleItemPosn > 0){
loadMoreItems();
}
}
}
protected abstract void loadMoreItems();
protected abstract int getTotalPageCount();
public abstract boolean isLoading();
public abstract boolean isLastPage();
}
在我的适配器中，我已经调用了addLoadingFooter的方法，该方法可以工作，但是进度条没有被取消，removeLoadingFooter被调用但由于页面索引小于页面而无法工作限制。
public class Top30Adapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private static final String TAG = Top30Adapter.class.getSimpleName();
private final Context context;
private List<UnsplashImages> itemsList;
private UnsplashImages unsplashImages;
private static final int ITEMS = 0;
private static final int PROGRESS = 1;
private boolean isLoadingAdded = false;
private boolean retryPageLoad = false;
private String errorMsg;
private PaginationAdapterCallback mCallback;
public Top30Adapter(Context context, List<UnsplashImages> itemsList) {
this.context = context;
this.itemsList = itemsList;
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
switch (viewType){
case ITEMS:
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.wallpaper_items_layout, parent, false);
return new WallpaperItemViewHolder(view);
case PROGRESS:
View pv = LayoutInflater.from(parent.getContext()).inflate(R.layout.progress_items_layout, parent, false);
return new LoadingViewHolder(pv);
}
return null;
}
@Override
public void onBindViewHolder(RecyclerView.ViewHolder viewholder, final int position) {
switch (getItemViewType(position)){
case ITEMS:
WallpaperItemViewHolder wallpaperItemViewHolder = (WallpaperItemViewHolder) viewholder;
unsplashImages = (UnsplashImages) itemsList.get(position);
Picasso.with(context)
.load(unsplashImages.getRegularImg())
.placeholder(R.drawable.drawer_header_trimmed)
.into(wallpaperItemViewHolder.wallpaperItemImg);
wallpaperItemViewHolder.favoriteWP_IV.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Favorites favorites = new Favorites();
favorites.setFavoritesId(UUID.randomUUID().toString());
favorites.setLargeImgURL(unsplashImages.getRegularImg());
favorites.setPreviewImgURL(unsplashImages.getRegularImg());
favorites.save();
Toast.makeText(context, "Added to Favorites", Toast.LENGTH_SHORT).show();
}
});
wallpaperItemViewHolder.setWallPaper_TV.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
final WallpaperManager wpm = WallpaperManager.getInstance(context);
Picasso.with(context)
.load(((UnsplashImages) itemsList.get(position)).getRegularImg())
.into(new Target() {
@Override
public void onBitmapLoaded(Bitmap bitmap, Picasso.LoadedFrom from) {
try {
wpm.setBitmap(bitmap);
Toast.makeText(context, "Your New Wallpaper Has Been Set", Toast.LENGTH_SHORT).show();
} catch (IOException e) {
e.printStackTrace();
}
}
@Override
public void onBitmapFailed(Drawable errorDrawable) {
Log.d(TAG, "Bitmap Load Failed");
Toast.makeText(context, "Could Not Set Wallpaper...Choose Another", Toast.LENGTH_SHORT).show();
}
@Override
public void onPrepareLoad(Drawable placeHolderDrawable) {
Log.d(TAG, "Prep to Load Bitmap");
}
});
}
});
break;
case PROGRESS:
LoadingViewHolder loadingViewHolder = (LoadingViewHolder) viewholder;
if (retryPageLoad){
loadingViewHolder.mErrorLayout.setVisibility(View.VISIBLE);
loadingViewHolder.mProgressBar.setVisibility(View.GONE);
loadingViewHolder.mErrorTxt.setText(errorMsg != null
? errorMsg
: context.getString(R.string.error_msg_unknown));
} else {
loadingViewHolder.mErrorLayout.setVisibility(View.GONE);
loadingViewHolder.mProgressBar.setVisibility(View.VISIBLE);
}
break;
}
}
@Override
public int getItemCount() {
if (itemsList == null) {
return 0;
}
return itemsList.size();
}
@Override
public int getItemViewType(int position) {
return (position == itemsList.size() - 1 && isLoadingAdded) ? PROGRESS : ITEMS;
}
public void addImage(UnsplashImages images){
itemsList.add(images);
notifyItemInserted(itemsList.size() - 1);
}
public void addAllImages(List<UnsplashImages> list){
for (UnsplashImages images : list){
addImage(images);
}
}
public void addLoadingFooter() {
isLoadingAdded = true;
addImage(new UnsplashImages());
}
public void removeLoadingFooter(){
isLoadingAdded = false;
int position = itemsList.size() - 1;
UnsplashImages unsplashImages = getItem(position);
if (unsplashImages != null){
itemsList.remove(unsplashImages);
notifyItemRemoved(position);
}
}
private UnsplashImages getItem(int position) {
return itemsList.get(position);
}
public void showRetry(boolean show, @Nullable String errorMsg){
retryPageLoad = true;
notifyItemChanged(itemsList.size() - 1);
if (errorMsg != null){this.errorMsg = errorMsg; } else { errorMsg = "Can't Fetch Wallpapers Now..."; }
}
}
完整的片段代码：
public class Top30Fragment extends Fragment {
private static final String TAG = Top30Fragment.class.getSimpleName();
private RecyclerView top30RV;
private List<UnsplashImages> itemsList = new ArrayList<>();
private Top30Adapter adapter;
private int PAGE_COUNT;
private static int PAGE_INDEX = 1;
private static int PER_PAGE = 20;
private static int CURRENT_PAGE = PAGE_INDEX;
private boolean isLoading = false;
private boolean isLastPage = false;
private String url = Constants.SEARCH_URL + "top30&page="+ PAGE_INDEX;
public Top30Fragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View vtop = inflater.inflate(R.layout.fragment_top30, container, false);
top30RV = vtop.findViewById(R.id.top30RV);
top30RV.setHasFixedSize(true);
LinearLayoutManager llm = new LinearLayoutManager(getActivity());
top30RV.setLayoutManager(llm);
if (Utils.isNetwork(getActivity())){
fetchWallpapers();
} else {
Snackbar.make(getActivity().findViewById(android.R.id.content), "Check Connection", Snackbar.LENGTH_LONG).show();
}
adapter = new Top30Adapter(getActivity(), itemsList);
top30RV.setAdapter(adapter);
top30RV.addOnScrollListener(new PaginationScrollListener(llm) {
@Override
protected void loadMoreItems() {
isLoading = true;
PAGE_INDEX = PAGE_INDEX + 1;
Log.d(TAG, "PIn:\t" + PAGE_INDEX);
loadNextPage();
}
@Override
protected int getTotalPageCount() {
return PAGE_COUNT;
}
@Override
public boolean isLoading() {
return isLoading;
}
@Override
public boolean isLastPage() {
return isLastPage;
}
});
adapter.notifyDataSetChanged();
return vtop;
}
private void loadNextPage() {
int newIndex = PAGE_INDEX +=1;
Log.d(TAG, "Next Page:\t" + newIndex);
Log.d(TAG, "Next Page Index:\t" + newIndex);
Log.d(TAG, "Next Page URL:\t" + url);
AndroidNetworking.get(url)
.setTag("Load Next Top30")
.setPriority(Priority.HIGH)
.build()
.getAsJSONObject(new JSONObjectRequestListener() {
@Override
public void onResponse(JSONObject response) {
Log.d(TAG, "Next Page Response:\t" + response.toString());
if (response != null){
isLoading = false;
adapter.removeLoadingFooter();
try {
JSONObject jsonObject = new JSONObject(response.toString());
JSONArray results = jsonObject.getJSONArray("results");
for (int p = 0; p < results.length(); p++){
JSONObject items = results.getJSONObject(p);
UnsplashImages images = new UnsplashImages();
images.setImageId(items.getString("id"));
JSONObject urls = items.getJSONObject("urls");
images.setRawImg(urls.getString("raw"));
images.setFullImg(urls.getString("full"));
images.setRegularImg(urls.getString("regular"));
images.setSmallImg(urls.getString("small"));
images.setThumbImg(urls.getString("thumb"));
itemsList.add(images);
adapter.notifyDataSetChanged();
Log.d(TAG, "New List Size:\t" + itemsList.size());
if (CURRENT_PAGE != PAGE_COUNT){
adapter.addLoadingFooter();
} else {
isLastPage = true;
}
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
@Override
public void onError(ANError anError) {
}
});
}
private void fetchWallpapers() {
// String url = Constants.SEARCH_URL + "top30&page="+ PAGE_INDEX + "per_page=" + PER_PAGE;
Log.d(TAG, "Top30 Unsplash URL:\t" + url);
AndroidNetworking.get(url)
.setPriority(Priority.HIGH)
.setTag("Get Seasons Wallpapers")
.build()
.getAsJSONObject(new JSONObjectRequestListener() {
@Override
public void onResponse(JSONObject response) {
Log.d(TAG, "Un-Response:\t" + response.toString());
if (response != null){
try {
JSONObject jsonObject = new JSONObject(response.toString());
PAGE_COUNT = jsonObject.getInt("total_pages");
Log.d(TAG, "Page Count:\t" + PAGE_COUNT);
JSONArray results = jsonObject.getJSONArray("results");
for (int p = 0; p < results.length(); p++){
JSONObject items = results.getJSONObject(p);
UnsplashImages images = new UnsplashImages();
images.setImageId(items.getString("id"));
JSONObject urls = items.getJSONObject("urls");
images.setRawImg(urls.getString("raw"));
images.setFullImg(urls.getString("full"));
images.setRegularImg(urls.getString("regular"));
images.setSmallImg(urls.getString("small"));
images.setThumbImg(urls.getString("thumb"));
itemsList.add(images);
adapter.notifyDataSetChanged();
Log.d(TAG, "List Size:\t" + itemsList.size());
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
@Override
public void onError(ANError anError) {
}
});
}
还有另一种方法来构造请求url以增加页面索引吗？谢谢。