三 PullToRefresh 上下拉

最新推荐文章于 2019-08-12 09:01:20 发布

原创最新推荐文章于 2019-08-12 09:01:20 发布 · 232 阅读

CC 4.0 BY-SA版权

本文介绍如何使用 PullToRefreshListView 控件实现上下拉刷新功能，包括布局设置、监听器配置及数据加载过程。

//导入Libray 设置依赖  复制布局

//布局

<com.handmark.pulltorefresh.library.PullToRefreshListView
    android:id="@+id/pull_refresh_list"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:cacheColorHint="#00000000"
    android:divider="#19000000"
    android:dividerHeight="4dp"
    android:fadingEdge="none"
    android:fastScrollEnabled="false"
    android:footerDividersEnabled="false"
    android:headerDividersEnabled="false"
    android:smoothScrollbar="true" />

//上下拉

package com.example.pulltorefresh;
import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
import com.google.gson.Gson;
import com.handmark.pulltorefresh.library.PullToRefreshBase;
import com.handmark.pulltorefresh.library.PullToRefreshListView;
import com.nostra13.universalimageloader.core.ImageLoader;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends AppCompatActivity {
//全局变量
    private PullToRefreshListView pull;
    String path="https://api.tianapi.com/wxnew/?key=8d6e3228d25298f13af4fc40ce6c9679&num=10";
    private Madapter madapter;
    private MasayTask masayTask;
    List<User.NewslistBean> arr=new ArrayList<>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //获取控件
        pull =(PullToRefreshListView) findViewById(R.id.pull_refresh_list);
        //默认下拉   设置BOTH可以上拉
        pull.setMode(PullToRefreshBase.Mode.BOTH);
        //显示数据
        new MasayTask().execute();
        //适配器
        madapter = new Madapter();
        pull.setAdapter(madapter);
        //设置监听PullToRefreshBase.OnRefreshListener2
        pull.setOnRefreshListener(new PullToRefreshBase.OnRefreshListener2<ListView>() {

            @Override
            public void onPullDownToRefresh(PullToRefreshBase<ListView> refreshView) {
                 arr.clear();
                 new MasayTask().execute();
            }

            @Override
            public void onPullUpToRefresh(PullToRefreshBase<ListView> refreshView) {
                new MasayTask().execute();
            }
        });
    }

    //适配器
    class Madapter extends BaseAdapter{

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

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

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

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            User.NewslistBean newslistBean = arr.get(position);
            ViewHolder vh;
            if (convertView==null){
                convertView= View.inflate(MainActivity.this, R.layout.list, null);
                vh = new ViewHolder();
                vh.tv=(TextView) convertView.findViewById(R.id.tv);
                vh.img=(ImageView) convertView.findViewById(R.id.img);
                convertView.setTag(vh);
            }else{
               vh=(ViewHolder) convertView.getTag();
            }
            ImageLoader.getInstance().displayImage(arr.get(position).getPicUrl(),vh.img);
            vh.tv.setText(arr.get(position).getTitle());
            return convertView;
        }

        class ViewHolder{
            TextView tv;
            ImageView img;
        }
    }


    //异步
    class MasayTask extends AsyncTask<String,Void,String>{
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
        }

        @Override
        protected void onPostExecute(String s) {
            super.onPostExecute(s);
            Gson gson = new Gson();
            User user = gson.fromJson(s, User.class);
            List<User.NewslistBean> newslist = user.getNewslist();
            arr.addAll(newslist);
            madapter.notifyDataSetChanged();//刷新适配器
            pull.onRefreshComplete(); //让刷新UI隐藏;
        }

        @Override
        protected void onProgressUpdate(Void... values) {
            super.onProgressUpdate(values);

        }

        @Override
        protected String doInBackground(String... params) {
            try {
                URL url = new URL(path);
                HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
                int responseCode = urlConnection.getResponseCode();
                if (responseCode==200){
                    InputStream inputStream = urlConnection.getInputStream();
                    BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
                    StringBuilder builder = new StringBuilder();
                    String string="";
                    while ((string=bufferedReader.readLine())!=null){
                        builder.append(string);
                    }
                    return  builder.toString();
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
            return null;
        }
    }
}