要在 AppWidget 中显示来自 Firebase 的数据，需要遵循以下步骤：

1. 在 AppWidgetProvider 中创建 RemoteViews 对象

RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.widget_layout); 

2. 创建一个服务（Service）类，并在其中使用 Firebase 实例查询数据：

class MyWidgetService extends RemoteViewsService { 

@Override 
public RemoteViewsFactory onGetViewFactory(Intent intent) { 
return new MyRemoteViewsFactory(getApplicationContext(), intent); 
} 

private class MyRemoteViewsFactory implements RemoteViewsService.RemoteViewsFactory { 

FirebaseDatabase firebaseDatabase; 
DatabaseReference databaseReference; 
List list = new ArrayList<>(); 
Context context; 

MyRemoteViewsFactory(Context context, Intent intent) { 
this.context = context; 
firebaseDatabase = FirebaseDatabase.getInstance(); 
databaseReference = firebaseDatabase.getReference("YOUR_REFERENCE_PATH"); 
} 

@Override 
public void onCreate() {} 

@Override 
public void onDataSetChanged() { 
list.clear(); 
databaseReference.addValueEventListener(new ValueEventListener() { 
@Override 
public void onDataChange(@NonNull DataSnapshot dataSnapshot) { 
for (DataSnapshot postSnapshot : dataSnapshot.getChildren()) { 
String item = postSnapshot.getValue(String.class); 
list.add(item); 
} 
} 

@Override 
public void onCancelled(@NonNull DatabaseError databaseError) { 
} 
}); 
} 

@Override 
public void onDestroy() {} 

@Override 
public int getCount() { 
return list.size(); 
} 

@Override 
public RemoteViews getViewAt(int position) { 
RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.list_item); 
views.setTextViewText(R.id.list_item_text, list.get(position)); 
return views; 
} 

@Override 
public RemoteViews getLoadingView() { 
return null; 
} 

@Override 
public int getViewTypeCount() { 
return 1; 
} 

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

@Override 
public boolean hasStableIds() { 
return true; 
} 
} 
} 

3. 在 AppWidgetProvider 中的 onUpdate 方法中，将 ListView 绑定到 MyWidgetService:

Intent intent = new Intent(context, MyWidgetService.class); 
views.setRemoteAdapter(R.id.widget_list_view, intent); 

4. 更新 WidgetManager，以在屏幕上显示 AppWidget:

ComponentName componentName = new ComponentName(context, YourAppWidgetProvider.class);
AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(context);
appWidgetManager.updateAppWidget(componentName, views);

尝试以上步骤后，您应该能够在