android - 拉动刷新不适用于 firebaseRecyclerAdapter

Question

我正在尝试使用向下滑动来刷新我的 Activity 。我的 Activity 与 Firebase 数据库同步，我正在使用 FirebaseRecyclerAdapter 从我的 firebase 帐户获取回收站中的所有数据。但是我的应用程序没有显示任何内容。即使是滑动操作也不会生成任何动画。

MainAcitivty.java

package com.example.admin.eventadmin;

import android.app.ProgressDialog;
import android.content.Context;
import android.os.AsyncTask;
import android.support.v4.widget.SwipeRefreshLayout;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;

import com.firebase.ui.database.FirebaseRecyclerAdapter;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.squareup.picasso.Picasso;

import java.util.HashMap;
import java.util.Map;
import java.util.Objects;

public class MainActivity extends AppCompatActivity {

    private RecyclerView r_event_list;
    private DatabaseReference mDatabaseRef;

    private ProgressDialog progressDialog;
    private SwipeRefreshLayout swipeRefreshLayout;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        progressDialog = new ProgressDialog(this);

        mDatabaseRef = FirebaseDatabase.getInstance().getReference().child("Event");

        r_event_list = (RecyclerView) findViewById(R.id.request_EventList);
        r_event_list.setHasFixedSize(true);
        r_event_list.setLayoutManager(new LinearLayoutManager(this));

        progressDialog = new ProgressDialog(this);
        swipeRefreshLayout = (SwipeRefreshLayout) findViewById(R.id.swipeContainer);

        swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
            @Override
            public void onRefresh() {
               refreshItems();
            }
        });

    }
    public void refreshItems(){
        loadItems();
    }


    public void loadItems(){

        FirebaseRecyclerAdapter<Event, RequestViewHolder> firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<Event, RequestViewHolder>(
                Event.class,
                R.layout.event_list_row,
                RequestViewHolder.class,
                mDatabaseRef
        ) {
            @Override
            protected void populateViewHolder(RequestViewHolder viewHolder, Event model, int position) {

                viewHolder.setTitle(model.getTitle());
                viewHolder.setDesc(model.getDesc());
                viewHolder.setCategory(model.getCategory());
                viewHolder.setLocation(model.getLocation());
                viewHolder.setPrice(model.getPrice());
                viewHolder.setImageUrl(getApplicationContext(), model.getImageUrl());

                swipeRefreshLayout.setRefreshing(false);

                final String title = model.getTitle();
                final String desc = model.getDesc();
                final String image = model.getImageUrl();
                final String category = model.getCategory();
                final String price = model.getPrice();
                final String location = model.getLocation();

                final DatabaseReference aRef = FirebaseDatabase.getInstance().getReference();

                viewHolder.verify_button.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        progressDialog.setMessage("Approving Event");
                        progressDialog.show();
                        String key = aRef.child("Approved Events").push().getKey();
                        Event event = new Event(title, image, price, category, location, desc);

                        Map<String, Object> eventValues = event.toMap();

                        Map<String, Object> childUpdates = new HashMap<>();

                        childUpdates.put("/ApprovedEvents/" + key, eventValues);

                        aRef.updateChildren(childUpdates);
                        progressDialog.dismiss();
                    }
                });
            }
        };
        r_event_list.setAdapter(firebaseRecyclerAdapter);
    }

    public static class RequestViewHolder extends RecyclerView.ViewHolder {
        View mView;
        public Button verify_button;


        public RequestViewHolder(View itemView) {
            super(itemView);
            mView = itemView;
            verify_button = (Button) mView.findViewById(R.id.approve_button);

        }

        public void setTitle(String title) {
            TextView request_title = (TextView) mView.findViewById(R.id.request_title);
            request_title.setText(title);
        }

        public void setDesc(String desc) {
            TextView request_desc = (TextView) mView.findViewById(R.id.request_desc);
            request_desc.setText(desc);
        }

        public void setLocation(String location) {
            TextView request_desc = (TextView) mView.findViewById(R.id.request_location);
            request_desc.setText(location);
        }

        public void setCategory(String category) {
            TextView request_category = (TextView) mView.findViewById(R.id.request_category);
            request_category.setText(category);
        }
        public void setPrice(String price) {
            TextView request_price = (TextView) mView.findViewById(R.id.request_price);
            request_price.setText(price);
        }

        public void setImageUrl(Context ctx, String imageUrl) {
            ImageView request_image = (ImageView) mView.findViewById(R.id.request_image);
            Picasso.with(ctx).load(imageUrl).into(request_image);
        }
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.admin.eventadmin.MainActivity">
<android.support.v4.widget.SwipeRefreshLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/swipeContainer">

    <android.support.v7.widget.RecyclerView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/request_EventList"
        android:clickable="true"/>

</android.support.v4.widget.SwipeRefreshLayout>
</RelativeLayout>

Answer 1

FirebaseRecyclerAdapter 从不需要“拉动刷新”操作。它始终与数据库中的数据同步。如果数据库中发生某些更改，只要您有网络连接，它就会自动反射(reflect)在适配器中。

您应该假设 FirebaseRecyclerAdapter 始终显示最新数据，并且在使用它时不要费心去刷新。