要使用监听器实现Firestore的无限分页,可以按照以下步骤进行:
RecyclerView.Adapter
,并实现onCreateViewHolder
、onBindViewHolder
和getItemCount
方法。public class MyAdapter extends RecyclerView.Adapter {
private List mDocuments;
public MyAdapter(List documents) {
mDocuments = documents;
}
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_layout, parent, false);
return new ViewHolder(view);
}
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
DocumentSnapshot document = mDocuments.get(position);
// 在这里设置文档数据到视图
}
@Override
public int getItemCount() {
return mDocuments.size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
// 在这里声明视图组件
public ViewHolder(View itemView) {
super(itemView);
// 在这里初始化视图组件
}
}
}
addSnapshotListener
方法可以实现实时更新。FirebaseFirestore db = FirebaseFirestore.getInstance();
CollectionReference collectionRef = db.collection("your_collection");
collectionRef.limit(10).addSnapshotListener(new EventListener() {
@Override
public void onEvent(QuerySnapshot documentSnapshots, FirebaseFirestoreException e) {
if (e != null) {
Log.e(TAG, "Listen failed: " + e);
return;
}
List documents = documentSnapshots.getDocuments();
MyAdapter adapter = new MyAdapter(documents);
recyclerView.setAdapter(adapter);
}
});
recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
LinearLayoutManager layoutManager = (LinearLayoutManager) recyclerView.getLayoutManager();
int visibleItemCount = layoutManager.getChildCount();
int totalItemCount = layoutManager.getItemCount();
int firstVisibleItemPosition = layoutManager.findFirstVisibleItemPosition();
if (!isLoading && (visibleItemCount + firstVisibleItemPosition) >= totalItemCount && firstVisibleItemPosition >= 0) {
loadMoreDocuments();
}
}
});
private void loadMoreDocuments() {
isLoading = true;
Query nextQuery = collectionRef.startAfter(lastVisibleDocument).limit(10);
nextQuery.addSnapshotListener(new EventListener() {
@Override
public void onEvent(QuerySnapshot documentSnapshots, FirebaseFirestoreException e) {
if (e != null) {
Log.e(TAG, "Listen failed: " + e);
return;
}
List newDocuments = documentSnapshots.getDocuments();
mDocuments.addAll(newDocuments);
adapter.notifyDataSetChanged();
if (!newDocuments.isEmpty()) {
lastVisibleDocument = newDocuments.get(newDocuments.size() - 1);
}
isLoading = false;
}
});
}
以上代码将使用RecyclerView
来显示Firestore文档列表,并在滚动到列表底部时加载更多文档。在loadMoreDocuments
方法中,使用startAfter
方法来获取下一个查询的起始点,并使用limit
方法限制每次加载的文档数量。
请注意,上述代码仅为示例,你需要根据自己的数据模型和需求进行适当的修改。