Android 如何使用firestore在回收器视图中加载批量数据?
我想知道如何使用firestore在recylcer视图中加载更多数据Android 如何使用firestore在回收器视图中加载批量数据?,android,firebase,android-recyclerview,google-cloud-firestore,Android,Firebase,Android Recyclerview,Google Cloud Firestore,我想知道如何使用firestore在recylcer视图中加载更多数据 Query query = FirebaseFirestore.getInstance() .collection("ie").limit(5); adapter=new InterviewAdapter(this,query); recyclerView.setAdapter(adapter); recyclerView.setLayoutManager(new LinearLayou
Query query = FirebaseFirestore.getInstance()
.collection("ie").limit(5);
adapter=new InterviewAdapter(this,query);
recyclerView.setAdapter(adapter);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
适配器类如下所示:
public class InterviewAdapter extends FireStoreAdapter<InterviewAdapter.ViewHolder> {
public interface OnInterviewSelectedListener {
void onInterviewSelected(DocumentSnapshot interview);
}
private InterviewAdapter.OnInterviewSelectedListener mListener;
public InterviewAdapter(Query query, OnInterviewSelectedListener listener) {
super(query);
mListener = listener;
}
@Override
public InterviewAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
LayoutInflater inflater = LayoutInflater.from(parent.getContext());
return new InterviewAdapter.ViewHolder(inflater.inflate(R.layout.ie, parent, false));
}
@Override
public void onBindViewHolder(InterviewAdapter.ViewHolder holder, int position) {
holder.bind(getSnapshot(position), mListener);
}
static class ViewHolder extends RecyclerView.ViewHolder {
TextView title,companyName,username,views,isHired;
public ViewHolder(View itemView) {
super(itemView);
title= (TextView) itemView.findViewById(R.id.title);
companyName= (TextView) itemView.findViewById(R.id.companyName);
username= (TextView) itemView.findViewById(R.id.username);
views= (TextView) itemView.findViewById(R.id.views);
isHired= (TextView) itemView.findViewById(R.id.isHired);
}
public void bind(final DocumentSnapshot snapshot,
final OnInterviewSelectedListener listener) {
InterviewExperience experience;
String companyName=snapshot.getString("companyName");
boolean isHired=Boolean.valueOf(snapshot.getBoolean("isHired"));
String username=snapshot.getString("username");
long views=new Double(Double.valueOf(snapshot.getDouble("views"))).longValue();
String id=snapshot.getId();
String title=snapshot.getString("title");
experience=new InterviewExperience(id,title,companyName,username,isHired,views,null,null);
this.title.setText(experience.getTitle());
this.companyName.setText("Company Name: "+experience.getCompanyName());
this.isHired.setText("Hired: "+experience.isHired());
this.views.setText("Views: "+experience.getViews()+"");
this.username.setText("Created By: "+experience.getUsername());
// Click listener
itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if (listener != null) {
listener.onInterviewSelected(snapshot);
}
}
});
}
}
}
public abstract class FireStoreAdapter<VH extends RecyclerView.ViewHolder>
extends RecyclerView.Adapter<VH>
implements EventListener<QuerySnapshot> {
private static final String TAG = "FirestoreAdapter";
private Query mQuery;
private ListenerRegistration mRegistration;
private ArrayList<DocumentSnapshot> mSnapshots = new ArrayList<>();
public FireStoreAdapter(Query query) {
mQuery = query;
}
@Override
public void onEvent(QuerySnapshot documentSnapshots, FirebaseFirestoreException e) {
if (e != null) {
Log.w(TAG, "onEvent:error", e);
onError(e);
return;
}
// Dispatch the event
Log.d(TAG, "onEvent:numChanges:" + documentSnapshots.getDocumentChanges().size());
for (DocumentChange change : documentSnapshots.getDocumentChanges()) {
switch (change.getType()) {
case ADDED:
onDocumentAdded(change);
break;
case MODIFIED:
onDocumentModified(change);
break;
case REMOVED:
onDocumentRemoved(change);
break;
}
}
onDataChanged();
}
public void startListening() {
if (mQuery != null && mRegistration == null) {
mRegistration = mQuery.addSnapshotListener(this);
}
}
public void stopListening() {
if (mRegistration != null) {
mRegistration.remove();
mRegistration = null;
}
mSnapshots.clear();
notifyDataSetChanged();
}
public void setQuery(Query query) {
// Stop listening
stopListening();
// Clear existing data
mSnapshots.clear();
notifyDataSetChanged();
// Listen to new query
mQuery = query;
startListening();
}
@Override
public int getItemCount() {
return mSnapshots.size();
}
protected DocumentSnapshot getSnapshot(int index) {
return mSnapshots.get(index);
}
protected void onDocumentAdded(DocumentChange change) {
mSnapshots.add(change.getNewIndex(), change.getDocument());
notifyItemInserted(change.getNewIndex());
}
protected void onDocumentModified(DocumentChange change) {
if (change.getOldIndex() == change.getNewIndex()) {
// Item changed but remained in same position
mSnapshots.set(change.getOldIndex(), change.getDocument());
notifyItemChanged(change.getOldIndex());
} else {
// Item changed and changed position
mSnapshots.remove(change.getOldIndex());
mSnapshots.add(change.getNewIndex(), change.getDocument());
notifyItemMoved(change.getOldIndex(), change.getNewIndex());
}
}
protected void onDocumentRemoved(DocumentChange change) {
mSnapshots.remove(change.getOldIndex());
notifyItemRemoved(change.getOldIndex());
}
protected void onError(FirebaseFirestoreException e) {};
protected void onDataChanged() {}
}
private void paginate(final DocumentSnapshot last, final int limit) {
final Query subset;
if (last == null) {
subset = db.collection("interviews")
.limit(limit);
} else {
subset = db.collection("interviews")
.startAfter(last)
.limit(limit);
}
setQuery(subset);
}
公共类InterviewAdapter扩展FireStoreAdapter{
InterviewSelectedListener上的公共界面{
已选择的访谈无效(文档快照访谈);
}
private InterviewAdapter.OnInterviewSelectedListener MLListener;
公共访谈适配器(查询,OnInterviewSelectedListener){
超级(查询);
mListener=监听器;
}
@凌驾
public InterviewAdapter.ViewHolder onCreateViewHolder(视图组父级,int-viewType){
LayoutInflater充气器=LayoutInflater.from(parent.getContext());
返回新的InterviewAdapter.ViewHolder(充气器充气(R.layout.ie,parent,false));
}
@凌驾
公共无效onBindViewHolder(InterviewAdapter.ViewHolder,int位置){
holder.bind(获取快照(位置),mListener);
}
静态类ViewHolder扩展了RecyclerView.ViewHolder{
文本视图标题、公司名称、用户名、视图、isHired;
公共视图持有者(视图项视图){
超级(项目视图);
title=(TextView)itemView.findViewById(R.id.title);
companyName=(TextView)itemView.findViewById(R.id.companyName);
username=(TextView)itemView.findViewById(R.id.username);
views=(TextView)itemView.findViewById(R.id.views);
isHired=(TextView)itemView.findViewById(R.id.isHired);
}
公共无效绑定(最终文档快照、,
最终OnInterviewSelectedListener(监听器){
面试经验;
String companyName=snapshot.getString(“companyName”);
boolean isHired=boolean.valueOf(snapshot.getBoolean(“isHired”);
字符串username=snapshot.getString(“用户名”);
长视图=新的Double(Double.valueOf(snapshot.getDouble(“视图”)).longValue();
String id=snapshot.getId();
String title=snapshot.getString(“title”);
经验=新的面试经验(id、标题、公司名称、用户名、isHired、视图、null、null);
this.title.setText(experience.getTitle());
this.companyName.setText(“公司名称:+experience.getCompanyName());
this.isHired.setText(“雇用:+experience.isHired());
this.views.setText(“视图:+experience.getViews()+”);
this.username.setText(“创建人:”+experience.getUsername());
//单击侦听器
itemView.setOnClickListener(新视图.OnClickListener(){
@凌驾
公共void onClick(视图){
if(侦听器!=null){
listener.onInterviewSelected(快照);
}
}
});
}
}
}
公共抽象类FireStoreAdapter
扩展RecyclerView.Adapter
实现EventListener{
私有静态最终字符串标记=“FirestoreAdapter”;
私有查询;
私人听众登记;
private ArrayList mSnapshots=new ArrayList();
公共FireStoreAdapter(查询){
mQuery=query;
}
@凌驾
public void OneEvent(QuerySnapshot文档快照,FireBaseFireStore异常e){
如果(e!=null){
Log.w(标记“onEvent:error”,e);
onError(e);
返回;
}
//发送事件
Log.d(标记“onEvent:numChanges:”+documentSnapshots.getDocumentChanges().size());
对于(DocumentChange:documentSnapshots.getDocumentChanges()){
开关(change.getType()){
案件补充:
OnDocuments已添加(更改);
打破
案例修改:
onDocumentModified(变更);
打破
已删除的案例:
OnDocument已删除(更改);
打破
}
}
onDataChanged();
}
公营机构{
if(mQuery!=null&&mRegistration==null){
mRegistration=mQuery.addSnapshotListener(此);
}
}
公营部门{
如果(mRegistration!=null){
mrregistration.remove();
mRegistration=null;
}
mSnapshots.clear();
notifyDataSetChanged();
}
公共void setQuery(查询){
//别再听了
停止倾听();
//清除现有数据
mSnapshots.clear();
notifyDataSetChanged();
//听新的查询
mQuery=query;
惊人的倾听();
}
@凌驾
public int getItemCount(){
返回mSnapshots.size();
}
受保护的文档快照getSnapshot(int索引){
返回mSnapshots.get(索引);
}
已添加受保护的文档无效(文档更改){
添加(change.getNewIndex(),change.getDocument());
notifyItemInserted(change.getNewIndex());
}
受保护的文档无效已修改(文档更改){
if(change.getoldinex()==change.getNewIndex()){
//项目已更改,但仍处于相同位置
mSnapshots.set(change.getOldIndex(),change.getDocument());
notifyItemChanged(change.getOldIndex());
}否则{
//项目变更和变更位置
mSnapshots.remove(change.getOldIndex());
添加(change.getNewIndex(),change.getDocument());
notifyItemMoved(change.getOldIndex(),change.getNewIndex());
}
}
已删除文档上的受保护无效(文档更改){
mSnapshots.remove(change.getOldIndex());
notifyItemRemoved(change.getOldIndex());
}
受保护的无效onError(FirebaseFirestoreException e){};
受保护的无效onDataChanged(){}
}
我使用了Firestore文档示例中给出的Firestore适配器代码。有人知道如何使用查询对象加载更多数据吗
当用户滚动到列表末尾时,如何在“回收器”视图中加载接下来的5项?您可以使用
Query
等方法,使用指定的DocumentSnapshot
对查询的结果进行分页
如果我认为您的收藏名为“访谈”,您可以像这样向FireStoreAdapter
添加一个方法
final List<DocumentChange> changes = documentSnapshots.getDocumentChanges();
final DocumentSnapshot lastDocument = changes.get(changes.size() - 1).getDocument();
paginate(lastDocument, 5);