PullToRefresh 上拉刷新,下拉加载网络数据 ListView

最新推荐文章于 2024-04-16 14:16:01 发布

Mike_8859

最新推荐文章于 2024-04-16 14:16:01 发布

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CC 4.0 BY-SA版权

本文链接：https://blog.youkuaiyun.com/Mike_chao/article/details/78284546

本文介绍了一个基于Android平台的新闻列表应用实现案例，该应用利用PullToRefreshListView组件实现了上下拉刷新功能，并通过AsyncTask异步获取网络数据，使用Gson进行JSON解析，展示了如何结合Universal Image Loader加载远程图片。

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package com.example.a1019;

import android.graphics.Bitmap;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Handler;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
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.ILoadingLayout;
import com.handmark.pulltorefresh.library.PullToRefreshBase;
import com.handmark.pulltorefresh.library.PullToRefreshListView;
import com.nostra13.universalimageloader.core.DisplayImageOptions;
import com.nostra13.universalimageloader.core.ImageLoader;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.List;

public class MainActivity extends AppCompatActivity {
    private PullToRefreshListView pull_lv;
    private Handler handler = new Handler();
    private String str = "";
    private List<Result.NewslistBean> newslist;
    private MyAdapter myAdapter;
    private int pageIndex = 1;
    private DisplayImageOptions options;

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




        //进行内存缓存
//进行sd卡缓存
/*.showImageOnLoading(R.drawable.ic_stub) // 设置正在下载中的图片
.showImageForEmptyUri(R.drawable.ic_empty) //没有请求地址时
.showImageOnFail(R.drawable.ic_error)//下载错误时*///设置图片质量



        new MyAsync().execute("https://api.tianapi.com/wxnew/?key=8d6e3228d25298f13af4fc40ce6c9679&num=10&page="+pageIndex);

        options = new DisplayImageOptions.Builder()
                .cacheInMemory(true)//进行内存缓存
                .cacheOnDisk(true)//进行sd卡缓存
                /*.showImageOnLoading(R.drawable.ic_stub) // 设置正在下载中的图片
                .showImageForEmptyUri(R.drawable.ic_empty) //没有请求地址时
                .showImageOnFail(R.drawable.ic_error)//下载错误时*/
                .bitmapConfig(Bitmap.Config.RGB_565)//设置图片质量
                .build();
        //设置监听
        initLV();

    }

    class MyAsync extends AsyncTask<String, Void, String> {

        @Override
        protected String doInBackground(String... params) {
            //创建Url对象
            try {
                URL url = new URL(params[0]);
                //打开连接
                HttpURLConnection connection = (HttpURLConnection) url.openConnection();
                //设置
                connection.setRequestMethod("GET");
                connection.setReadTimeout(3000);
                connection.setConnectTimeout(3000);
                int code = connection.getResponseCode();
                if (code == 200) {
                    InputStream inputStream = connection.getInputStream();
                    str = streamToString(inputStream);
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
            return str;
        }

        @Override
        protected void onPostExecute(String s) {
            super.onPostExecute(s);
            Log.e("ZZZ",s+"11111111111111111");
            //解析数据
            Gson gson = new Gson();
            Result result = gson.fromJson(str, Result.class);
            newslist = result.getNewslist();

            setAdapter();


        }

    }

   public String streamToString(InputStream is) {
                StringBuilder sb = new StringBuilder();
                String con;
                BufferedReader br = new BufferedReader(new InputStreamReader(is));
                try {
                    while ((con = br.readLine()) != null) {
                        sb.append(con);
                    }
                } catch (IOException e) {
// TODO Auto-generated catch block
                    e.printStackTrace();
                }

                return sb.toString();

            }


            private void initLV() {
                //设置支持上拉下拉刷新
                pull_lv.setMode(PullToRefreshBase.Mode.BOTH);
                //设置状态
                ILoadingLayout startLabels = pull_lv.getLoadingLayoutProxy(true, false);
                startLabels.setPullLabel("下拉刷新");
                startLabels.setRefreshingLabel("正在拉");
                startLabels.setReleaseLabel("放开刷新");


                ILoadingLayout endLabels = pull_lv.getLoadingLayoutProxy(false, true);
                endLabels.setPullLabel("上拉刷新");
                endLabels.setRefreshingLabel("正在载入...");
                endLabels.setReleaseLabel("放开刷新...");

                //设置监听事件
                pull_lv.setOnRefreshListener(new PullToRefreshBase.OnRefreshListener2<ListView>() {
                    @Override
                    public void onPullDownToRefresh(PullToRefreshBase<ListView> refreshView) {
                        //下拉刷新的回调方法
                        //下拉刷新的数据，显示在listview列表的最上面
                        addtoTop();
                       // pageIndex=1;
                        handler.postDelayed(new Runnable() {
                            @Override
                            public void run() {
                                //刷新完成，必须在异步下完成
                                pull_lv.onRefreshComplete();
                                //刷新适配器
                                setAdapter();

                            }
                        }, 1000);
                    }

                    @Override
                    public void onPullUpToRefresh(PullToRefreshBase<ListView> refreshView) {
                        //上拉加载的回调
                        //加载更多的数据，添加到集合列表的最后面
                        addtoBottom();
                        pageIndex++;
                        handler.postDelayed(new Runnable() {
                            @Override
                            public void run() {
                                //刷新完成，必须在异步下完成
                                pull_lv.onRefreshComplete();
                                //刷新适配器
                                setAdapter();
                            }
                        }, 1000);
                    }
                });
            }

    private void addtoBottom() {
        pageIndex++;
        new MyAsync().execute("https://api.tianapi.com/wxnew/?key=8d6e3228d25298f13af4fc40ce6c9679&num=10&page="+pageIndex);
    }

    private void addtoTop() {
        pageIndex=1;
        new MyAsync().execute("https://api.tianapi.com/wxnew/?key=8d6e3228d25298f13af4fc40ce6c9679&num=10&page="+pageIndex);

    }


    private void setAdapter() {
                if (myAdapter == null) {
                    myAdapter = new MyAdapter();
                    pull_lv.setAdapter(myAdapter);
                } else {
                    myAdapter.notifyDataSetChanged();
                }
            }

            class MyAdapter extends BaseAdapter {

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

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

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

                @Override
                public View getView(int position, View convertView, ViewGroup parent) {
                    View view = View.inflate(MainActivity.this, R.layout.item, null);
                    ImageView img =(ImageView) view.findViewById(R.id.img);
                    TextView tv = (TextView) view.findViewById(R.id.tv);

                    ImageLoader.getInstance().displayImage(newslist.get(position).getPicUrl(),img,options);
                    tv.setText(newslist.get(position).getTitle());
                    return view;
                }
            }

}

//布局

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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"
    xmlns:ptr="http://schemas.android.com/apk/res-auto"
    tools:context="com.example.a1019.MainActivity">

    <com.handmark.pulltorefresh.library.PullToRefreshListView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/pull_lv"
        ptr:ptrDrawable="@drawable/default_ptr_flip"
        ptr:ptrAnimationStyle="flip"
        ptr:ptrHeaderBackground="#383838"
        ptr:ptrHeaderTextColor="#FFFFFF"
        ></com.handmark.pulltorefresh.library.PullToRefreshListView>