我在我的应用程序中使用博客 API、改造和 MVVM，我尝试在用户滚动时使用分页来加载更多帖子，这里发生的问题是响应正在加载它自己“相同的列表/相同的十个帖子再次加载”
这是我的代码
帖子客户端类
public class PostsClient {
private static final String TAG = "PostsClient";
private static final String KEY = "XYZ sensitive key!";
private static final String BASE_URL = "https://www.googleapis.com/blogger/v3/blogs/4294497614198718393/";
private PostInterface postInterface;
private static PostsClient INSTANCE;
public PostsClient() {
Retrofit retrofit = new Retrofit.Builder()
.baseUrl(BASE_URL)
.addConverterFactory(GsonConverterFactory.create())
.build();
postInterface = retrofit.create(PostInterface.class);
}
public static PostsClient getINSTANCE() {
if(INSTANCE == null){
INSTANCE = new PostsClient();
}
return INSTANCE;
}
public Call<PostList> getPostList(){
return postInterface.getPostList(KEY);
}
}
public class PostViewModel extends ViewModel {
public static final String TAG = "PostViewModel";
public MutableLiveData<PostList> postListMutableLiveData = new MutableLiveData<>();
public MutableLiveData<PostList> postListByLabelMutableLiveData = new MutableLiveData<>();
public MutableLiveData<String> finalURL = new MutableLiveData<>();
public MutableLiveData<String> token = new MutableLiveData<>();
public void getPosts(){
if (token.getValue() != "") {
finalURL.setValue(finalURL.getValue() + "&pageToken=" + token.getValue());
}
if (token == null) {
return;
}
PostsClient.getINSTANCE().getPostList().enqueue(new Callback<PostList>() {
@Override
public void onResponse(@NotNull Call<PostList> call, @NotNull Response<PostList> response) {
PostList list = response.body();
if (list.getItems() != null) {
token.setValue(list.getNextPageToken());
postListMutableLiveData.setValue(list);
}
Log.i(TAG,response.body().getItems().toString());
}
@Override
public void onFailure(Call<PostList> call, Throwable t) {
Log.e(TAG,t.getMessage());
}
});
}
public void getPostListByLabel(){
PostsByLabelClient.getINSTANCE().getPostListByLabel(finalURL.getValue()).enqueue(new Callback<PostList>() {
@Override
public void onResponse(Call<PostList> call, Response<PostList> response) {
postListByLabelMutableLiveData.setValue(response.body());
}
@Override
public void onFailure(Call<PostList> call, Throwable t) {
}
});
}
}
public class HomeFragment extends Fragment {
private PostViewModel postViewModel;
public static final String TAG = "HomeFragment";
private RecyclerView recyclerView;
private PostAdapter postAdapter;
private List<Item> itemArrayList;
private boolean isScrolling = false;
private int currentItems, totalItems, scrollOutItems, selectedIndex;
public View onCreateView(@NonNull LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
postViewModel = new ViewModelProvider(this).get(PostViewModel.class);
postViewModel.getPosts();
View root = inflater.inflate(R.layout.fragment_home, container, false);
itemArrayList = new ArrayList<>();
recyclerView = root.findViewById(R.id.homeRecyclerView);
postAdapter = new PostAdapter(getContext(),itemArrayList);
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getContext());
linearLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);
recyclerView.setLayoutManager(linearLayoutManager);
DividerItemDecoration dividerItemDecoration = new DividerItemDecoration(recyclerView.getContext()
, linearLayoutManager.getOrientation());
recyclerView.setLayoutManager(linearLayoutManager);
recyclerView.addItemDecoration(dividerItemDecoration);
recyclerView.setAdapter(postAdapter);
// textView.setText(s);
postViewModel.postListMutableLiveData.observe(HomeFragment.this, new Observer<PostList>() {
@Override
public void onChanged(PostList postList) {
itemArrayList.addAll(postList.getItems());
postAdapter.notifyDataSetChanged();
}
});
recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrollStateChanged(@NonNull RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
isScrolling = true;
}
@Override
public void onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
if (dy > 0) {
currentItems = linearLayoutManager.getChildCount();
totalItems = linearLayoutManager.getItemCount();
scrollOutItems = linearLayoutManager.findFirstVisibleItemPosition();
if (isScrolling && (currentItems + scrollOutItems == totalItems)) {
isScrolling = false;
postViewModel.getPosts();
postAdapter.notifyDataSetChanged();
}
}
}
});
return root;
}
}
在 PostViewModel 上
我创建了一个变量
public MutableLiveData<String> token = new MutableLiveData<>();这个代表一个新页面/响应的 token 将带有“每个页面都有一个列表/十个新帖子”在 HomeFragment 上
我创建了三个整数值
private int currentItems, totalItems, scrollOutItems, selectedIndex;和一个 bool 值private boolean isScrolling = false;然后我用了recyclerView.addOnScrollListener用这种方式加载接下来的十个帖子，但它不像我之前说的那样工作，它加载相同的结果/列表The result on imgur.com
最佳答案
经过数百次尝试，我终于解决了，这是问题的解决方案
首先我更改了 GET API 中的方法 PostInterface并让它采取@URL而不是 @Query像这样的KEY
public interface PostInterface {
@GET
Call<PostList> getPostList(@Url String URL);
}
PostsClient从 BASE_URL 中删除最终结果private static String BASE_URL并为 创建一个 setter 和 getter基本 URL 和 key public static String getKEY() {
return KEY;
}
public static String getBaseUrl() {
return BASE_URL;
}
public void getPosts(){
Log.e(TAG,finalURL.getValue());
PostsClient.getINSTANCE().getPostList(finalURL.getValue()).enqueue(new Callback<PostList>() {
@Override
public void onResponse(@NotNull Call<PostList> call, @NotNull Response<PostList> response) {
PostList list = response.body();
if (list.getItems() != null) {
Log.e(TAG,list.getNextPageToken());
token.setValue(list.getNextPageToken());
postListMutableLiveData.setValue(list);
}
if (token.getValue() == null || !token.getValue().equals("") ) {
finalURL.setValue(finalURL.getValue() + "&pageToken=" + token.getValue());
}
// Log.i(TAG,response.body().getItems().toString());
}
@Override
public void onFailure(Call<PostList> call, Throwable t) {
Log.e(TAG,t.getMessage());
}
});
}
关于android - recyclerView.addOnScrollListener - "retrofit pagination with MVVM"正在加载相同的响应/列表，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/66156640/