Android开源库——PullToRefresh

类似SlidingMenu也是一个开源组件，集成的方式也类似，不赘述，可以参考

https://blog.csdn.net/nishigesb123/article/details/90261849

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PullToRefresh

概述

使用 PullToRefresh 可以实现对多种控件进行下拉刷新、上拉加载操作，还可以实现自定义刷新和加载部分视图等操作。

项目地址：https://github.com/chrisbanes/Android-PullToRefresh

Pull To Refresh Views for Android

This project aims to provide a reusable Pull to Refresh widget for Android. It was originally based on Johan Nilsson's library(mainly for graphics, strings and animations), but these have been replaced since.

Features

• Supports both Pulling Down from the top, and Pulling Up from the bottom (or even both).
• Animated Scrolling for all devices.
• Over Scroll supports for devices on Android v2.3+.
• Currently works with:
  • ListView
  • ExpandableListView
  • GridView
  • WebView
  • ScrollView
  • HorizontalScrollView
  • ViewPager
• Integrated End of List Listener for use of detecting when the user has scrolled to the bottom.
• Maven Support.
• Indicators to show the user when a Pull-to-Refresh is available.
• Support for ListFragment!
• Lots of Customisation options!

Repository at https://github.com/chrisbanes/Android-PullToRefresh.

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使用PullToRefresh实现列表刷新

添加布局文件

首先有一条添加“命名空间”的语句需要设置一下，图示处找个位置加进去就好~

xmlns:ptr="http://schemas.android.com/apk/res-auto"

然后是组件

• ptrDrawable表示图片资源（代码中使用了library里的一个默认资源，大概是一个下拉箭头的样子）
• ptrAnimationStyle为动画效果，有两种，flip表示上下，还有一个是rotate表示旋转
• 剩下两组ptr开头的参数分别是背景和文本颜色

列表

一般情况下，下拉刷新的操作肯定是对列表而言的，我们这里也不例外。所以既然是对列表而言，所以我们还得先准备一个列表。

首先是列表数据对象

package com.example.a5_16pulltorefresh;

public class Music {
    //标题
    private String title;
    //歌手
    private String singer;

    public Music() {
    }

    public Music(String title, String singer) {
        this.title = title;
        this.singer = singer;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getSinger() {
        return singer;
    }

    public void setSinger(String singer) {
        this.singer = singer;
    }
}

列表项布局文件

完整代码

package com.example.a5_16pulltorefresh;

import android.content.Context;
import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ListView;
import android.widget.TextView;

import com.handmark.pulltorefresh.library.ILoadingLayout;
import com.handmark.pulltorefresh.library.PullToRefreshBase;
import com.handmark.pulltorefresh.library.PullToRefreshListView;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {
    private PullToRefreshListView lv;
    //音乐列表
    private ArrayList musics = new ArrayList<>();
    private DataAdapter dataAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        lv = findViewById(R.id.pull_to_refresh_listView);

        //不带2的只用实现一个刷新方法
        //        lv.setOnRefreshListener(new PullToRefreshBase.OnRefreshListener() {
        //            @Override
        //            public void onRefresh(PullToRefreshBase refreshView) {
        //
        //            }
        //        });
        //带2的是上下刷新可以单独实现方法
        lv.setOnRefreshListener(new PullToRefreshBase.OnRefreshListener2() {
            @Override
            public void onPullDownToRefresh(PullToRefreshBase refreshView) {
                new LoadDataAsyncTask(MainActivity.this).execute();
            }

            @Override
            public void onPullUpToRefresh(PullToRefreshBase refreshView) {
                new LoadDataAsyncTask(MainActivity.this).execute();
            }
        });
        //设置模式——BOTH表示上下都可以
        lv.setMode(PullToRefreshBase.Mode.BOTH);
        //设置刷新时显示的文本
        //下拉
        ILoadingLayout startLayout = lv.getLoadingLayoutProxy(true, false);
        startLayout.setPullLabel("正在下拉刷新...");
        startLayout.setRefreshingLabel("正在玩命加载中...");
        startLayout.setReleaseLabel("放开刷新...");
        //上拉
        ILoadingLayout endLayout = lv.getLoadingLayoutProxy(false, true);
        endLayout.setPullLabel("正在上拉刷新...");
        endLayout.setRefreshingLabel("正在玩命加载中...");
        endLayout.setReleaseLabel("放开刷新...");

        //调用一次
        loadData();
        dataAdapter = new DataAdapter(this, musics);
        lv.setAdapter(dataAdapter);
    }

    //异步类
    static class LoadDataAsyncTask extends AsyncTask {
        private MainActivity mainActivity;

        //静态方法，需要传...
        public LoadDataAsyncTask(MainActivity mainActivity) {
            this.mainActivity = mainActivity;
        }

        @Override
        protected String doInBackground(Void... voids) {
            try {
                Thread.sleep(2000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            mainActivity.loadData();
            return "success";
        }

        //完成数据的话...
        @Override
        protected void onPostExecute(String s) {
            super.onPostExecute(s);
            if ("success".equals(s)) {
                mainActivity.dataAdapter.notifyDataSetChanged();//通知数据集发生改变
                mainActivity.lv.onRefreshComplete();//表示刷新完成
            }
        }
    }

    //模拟一组数据
    private int count = 1;

    private void loadData() {
        for (int i = 0; i < 10; i++) {
            musics.add(new Music("歌曲-" + count, "歌手-" + count));
            count++;
        }
    }

    static class DataAdapter extends BaseAdapter {
        private Context ctx;
        private ArrayList musics;

        //构造器传上下文
        public DataAdapter(Context context, ArrayList musics) {
            this.ctx = context;
            this.musics = musics;
        }

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

        @Override
        public Object getItem(int position) {
            return musics.get(position);
        }

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

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            ViewHolder vh;
            //码一下
            if (convertView == null) {
                convertView = LayoutInflater.from(ctx).inflate(R.layout.list_item, null);
                vh = new ViewHolder();
                vh.tv_title = convertView.findViewById(R.id.title);
                vh.tv_singer = convertView.findViewById(R.id.singer);
                convertView.setTag(vh);
            }
            vh = (ViewHolder) convertView.getTag();
            Music m = musics.get(position);
            vh.tv_title.setText(m.getTitle());
            vh.tv_singer.setText(m.getSinger());
            return convertView;
        }

        static class ViewHolder {
            TextView tv_title;
            TextView tv_singer;
        }
    }

}

测试效果