Android 使用SwipeRefreshLayout实现RecyclerVeiw的下拉刷新和上拉加载

Posted 2021-07-11 路宇_

实现下拉刷新和上拉加载的完整代码如下：

一、布局文件代码如下：
主界面main.xml代码:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <androidx.swiperefreshlayout.widget.SwipeRefreshLayout
        android:id="@+id/refreshLayout"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <androidx.recyclerview.widget.RecyclerView
            android:id="@+id/recyclerView"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            />
    </androidx.swiperefreshlayout.widget.SwipeRefreshLayout>

</LinearLayout>

item的列表布局：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    >

    <TextView
        android:id="@+id/tv"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:background="@android:color/holo_blue_dark"
        android:gravity="center"
        android:textSize="30sp"
        android:textColor="#ffffff"
        android:text="11"
        android:layout_marginBottom="1dp"/>

</LinearLayout>

底部footView的布局代码如下：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    >
    <TextView
        android:id="@+id/tips"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:padding="10dp"
        android:textSize="15sp"
        android:layout_marginBottom="1dp"/>
</LinearLayout>

二、后台代码逻辑代码如下：
适配器MyAdapter代码如下：
具体的详解已经在注释中写出

package com.example.swiperefreshdemo;

import android.content.Context;
import android.os.Handler;
import android.os.Looper;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ProgressBar;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

import java.util.ArrayList;
import java.util.List;

public class MyAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
    private List<String> datas;
    private Context context;
    private int normalType = 0;
    private int footType = 1;
    private boolean hasMore = true;
    private boolean fadeTips = false;
    private Handler mHandler = new Handler(Looper.getMainLooper());

    public MyAdapter(List<String> datas, Context context, boolean hasMore) {
        this.datas = datas;
        this.context = context;
        this.hasMore = hasMore;
    }

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        if (viewType == normalType) {
            return new NormalHolder(LayoutInflater.from(context).inflate(R.layout.item, null));
        } else {
            return new FootHolder(LayoutInflater.from(context).inflate(R.layout.footview, null));
        }
    }

    @Override
    public void onBindViewHolder(final RecyclerView.ViewHolder holder, int position) {
        if (holder instanceof NormalHolder) {
            ((NormalHolder) holder).textView.setText(datas.get(position));
        } else {
            ((FootHolder) holder).tips.setVisibility(View.VISIBLE);
            if (hasMore == true) {
                fadeTips = false;
                if (datas.size() > 0) {
                    ((FootHolder) holder).tips.setText("正在加载更多...");
                }
            } else {
                if (datas.size() > 0) {
                    ((FootHolder) holder).tips.setText("没有更多数据了");
                    mHandler.postDelayed(new Runnable() {
                        @Override
                        public void run() {
                            ((FootHolder) holder).tips.setVisibility(View.GONE);
                            fadeTips = true;
                            hasMore = true;
                        }
                    }, 500);
                }
            }
        }
    }

    @Override
    public int getItemCount() {
        return datas.size() + 1;
    }

    public int getRealLastPosition() {
        return datas.size();
    }


    public void updateList(List<String> newDatas, boolean hasMore) {
        if (newDatas != null) {
            datas.addAll(newDatas);
        }
        this.hasMore = hasMore;
        notifyDataSetChanged();
    }

    class NormalHolder extends RecyclerView.ViewHolder {
        private TextView textView;

        public NormalHolder(View itemView) {
            super(itemView);
            textView = (TextView) itemView.findViewById(R.id.tv);
        }
    }

    class FootHolder extends RecyclerView.ViewHolder {
        private TextView tips;

        public FootHolder(View itemView) {
            super(itemView);
            tips = (TextView) itemView.findViewById(R.id.tips);
        }
    }

    public boolean isFadeTips() {
        return fadeTips;
    }

    public void resetDatas() {
        datas = new ArrayList<>();
    }

    @Override
    public int getItemViewType(int position) {
        if (position == getItemCount() - 1) {
            return footType;
        } else {
            return normalType;
        }
    }
}

MainActivity代码如下：

package com.example.swiperefreshdemo;

import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.DefaultItemAnimator;
import androidx.recyclerview.widget.GridLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import androidx.swiperefreshlayout.widget.SwipeRefreshLayout;

import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity implements SwipeRefreshLayout.OnRefreshListener {

    //声明一个下拉刷新的对象
    private SwipeRefreshLayout refreshLayout;
    private RecyclerView recyclerView;
    private List<String> list;

    private int lastVisibleItem = 0;
    private final int PAGE_COUNT = 30;
    //声明一个网格布局管理器
    private GridLayoutManager mLayoutManager;
    private MyAdapter adapter;
    private Handler mHandler = new Handler(Looper.getMainLooper());

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        initData();
        findView();
        initRefreshLayout();
        initRecyclerView();
    }
    private void initData() {
        list = new ArrayList<>();
        for (int i = 1; i <= 60; i++) {
            list.add("条目" + i);
        }
    }


    private void findView() {
        //从布局文件中获取名叫refreshLayout的下拉刷新布局
        refreshLayout = (SwipeRefreshLayout) findViewById(R.id.refreshLayout);
        recyclerView = (RecyclerView) findViewById(R.id.recyclerView);

    }

    private void initRefreshLayout() {
        //设置下拉刷新布局的进度圆圈颜色
        refreshLayout.setColorSchemeResources(android.R.color.holo_blue_light, android.R.color.holo_red_light,
                android.R.color.holo_orange_light, android.R.color.holo_green_light);
        //给refreshLayout设置下拉刷新监听器
        refreshLayout.setOnRefreshListener(this);
    }

    private void initRecyclerView() {
        adapter = new MyAdapter(getDatas(0, PAGE_COUNT), this, getDatas(0, PAGE_COUNT).size() > 0 ? true : false);
        //网格布局管理器,参数设置为1,表示该数据独占一行
        mLayoutManager = new GridLayoutManager(this, 1);
        recyclerView.setLayoutManager(mLayoutManager);
        recyclerView.setAdapter(adapter);
        recyclerView.setItemAnimator(new DefaultItemAnimator());

        recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
                super.onScrollStateChanged(recyclerView, newState);
                if (newState == RecyclerView.SCROLL_STATE_IDLE) {
                    //判断是否滑动到底部
                    if (adapter.isFadeTips() == false && lastVisibleItem + 1 == adapter.getItemCount()) {
                        mHandler.postDelayed(new Runnable() {
                            @Override
                            public void run() {
                                //加载更多数据,一次加载40个数据
                                updateRecyclerView(adapter.getRealLastPosition(), adapter.getRealLastPosition() + PAGE_COUNT);
                            }
                        }, 500);
                    }

                    if (adapter.isFadeTips() == true && lastVisibleItem + 2 == adapter.getItemCount()) {
                        mHandler.postDelayed(new Runnable() {
                            @Override
                            public void run() {
                                updateRecyclerView(adapter.getRealLastPosition(), adapter.getRealLastPosition() + PAGE_COUNT);
                            }
                        }, 500);
                    }
                }
            }

            @Override
            public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                super.onScrolled(recyclerView, dx, dy);
                //findLastVisibleItemPosition显示界面的最后一个位置
                lastVisibleItem = mLayoutManager.findLastVisibleItemPosition();
            }
        });
    }

    private List<String> getDatas(final int firstIndex, final int lastIndex) {
        List<String> resList = new ArrayList<>();
        for (int i = firstIndex; i < lastIndex; i++) {
            if (i < list.size()) {
                resList.add(list.get(i));
            }
        }
        return resList;
    }

    private void updateRecyclerView(int fromIndex, int toIndex) {
        List<String> newDatas = getDatas(fromIndex, toIndex);
        if (newDatas.size() > 0) {
            adapter.updateList(newDatas, true);
        } else {
            adapter.updateList(null, false);
        }
    }

    @Override
    public void onRefresh() {
        refreshLayout.setRefreshing(true);
        adapter.resetDatas();
        updateRecyclerView(0, PAGE_COUNT);
        mHandler.postDelayed(new Runnable() {
            @Override
            public void run() {
                refreshLayout.setRefreshing(false);
            }
        }, 1000);
    }
}

以上就是实现下拉刷新和上拉加载的完整代码，这是加载的本地数据，如果在项目中运用的话，把本地获取数据，替换为网络获取即可。
效果图如下：

免费源码下载

这个功能就到此结束了，写的很简陋，有不当之处，可在评论区指正，一起学习，共同进步！