使用自定义的item、Adapter和AsyncTask、第三方开源框架PullToRefresh联合使用实现自定义的下拉列表（从网络加载图片显示在item中的ImageView）

AsyncTask使用方法详情：http://www.cnblogs.com/zzw1994/p/4959949.html

下拉开源框架PullToRefresh使用方法和下载详情：http://www.cnblogs.com/zzw1994/p/4992194.html

具体实现的代码如下：

item.xml：

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

    <ImageView
        android:id="@+id/imageView1"
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:layout_alignParentLeft="true"
        android:src="@drawable/ic_launcher" />

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBottom="@+id/imageView1"
        android:layout_alignParentTop="true"
        android:layout_toLeftOf="@+id/imageView2"
        android:layout_toRightOf="@+id/imageView1"
        android:gravity="center"
        android:text="TextView"
       android:textColor="@android:color/holo_red_light"
        android:textSize="30sp" />

    <ImageView
        android:id="@+id/imageView2"
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:layout_alignParentRight="true"
        android:layout_alignParentTop="true"
        android:src="@drawable/ic_launcher" />
    
</RelativeLayout>

activity_main.xml:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.zzw.testpulltorefresh.MainActivity" >

    <com.handmark.pulltorefresh.library.PullToRefreshListView
        android:id="@+id/listView"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</RelativeLayout>

MainActivity.java:

package com.zzw.testpulltorefresh;

import java.io.BufferedInputStream;
import java.io.ByteArrayOutputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;

import com.handmark.pulltorefresh.library.PullToRefreshBase;
import com.handmark.pulltorefresh.library.PullToRefreshBase.Mode;
import com.handmark.pulltorefresh.library.PullToRefreshBase.OnRefreshListener;
import com.handmark.pulltorefresh.library.PullToRefreshListView;

import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Color;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity {
    private int COUNT = 0;

    private final String IMAGE_KEY1 = "IMAGE_KEY1";
    private final String IMAGE_KEY2 = "IMAGE_KEY2";
    private final String TEXT_KEY = "TEXT_KEY";

    private PullToRefreshListView listView;
    private ArrayList<HashMap<String, Object>> data;
    private ArrayAdapter adapter;
    private String[] urls = { "http://p1.so.qhimg.com/bdr/_240_/t01829c584b50b68311.jpg",
            "http://p2.so.qhimg.com/bdr/_240_/t011c2cd4fe8723bcb2.jpg",
            "http://p4.so.qhimg.com/bdr/_240_/t01b11db3c0961b24a9.jpg",
            "http://p4.so.qhimg.com/bdr/_240_/t019786092c7b1688b9.jpg",
            "http://p4.so.qhimg.com/bdr/_240_/t015b226d64a10097ce.jpg",
            "http://p1.so.qhimg.com/bdr/_240_/t01f6c4382c907133ab.jpg" };

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

        data = new ArrayList<HashMap<String, Object>>();

        listView = (PullToRefreshListView) findViewById(R.id.listView);

        // 设置向下滑动时刷新
        listView.setMode(Mode.PULL_FROM_START);
        // 支持下拉和上拉 listView.setMode(Mode.BOTH);

        // 设置监听
        listView.setOnRefreshListener(new OnRefreshListener<ListView>() {

            @Override
            public void onRefresh(PullToRefreshBase<ListView> refreshView) {
                // 在这完成业务逻辑
                new MyAsyncTask().execute();
            }
        });

        adapter = new MyAdapter(this, R.layout.item);
        listView.setAdapter(adapter);

        // 设置如果数据为空的时候显示什么
        TextView textView = new TextView(this);
        textView.setText("请下拉刷新");
        listView.setEmptyView(textView);
    }

    //自定义的Item显示参数设置在Adapter中操作
    private class MyAdapter extends ArrayAdapter {

        private LayoutInflater inflater;
        private int item;

        public MyAdapter(Context context, int resource) {
            super(context, resource);
            inflater = LayoutInflater.from(context);
            this.item = resource;
        }

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

        @Override
        public HashMap<String, Object> getItem(int position) {

            return data.get(position);
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            HashMap<String, Object> map = getItem(position);

            if (convertView == null) {
                convertView = inflater.inflate(item, null);
            }

            ImageView image1 = (ImageView) convertView.findViewById(R.id.imageView1);
            ImageView image2 = (ImageView) convertView.findViewById(R.id.imageView2);
            TextView textView = (TextView) convertView.findViewById(R.id.textView);

            image1.setImageBitmap((Bitmap) map.get(IMAGE_KEY1));
            image2.setImageBitmap((Bitmap) map.get(IMAGE_KEY2));
            textView.setText(map.get(TEXT_KEY) + "");

            if (position % 2 == 1) {
                textView.setTextColor(Color.BLUE);
            }

            return convertView;
        }

    }

    
    //联网等一系列延时操作在AsyncTask中操作
    private class MyAsyncTask extends AsyncTask {

        @Override
        protected void onPreExecute() {
            // 开始刷新
            listView.setRefreshing();
        }

        @Override
        protected Object doInBackground(Object... params) {
            HashMap<String, Object> map = new HashMap<String, Object>();
            try {
                byte[] buf = loadRawDataFromURL(urls[COUNT]);
                BitmapFactory factory = new BitmapFactory();
                Bitmap bitmap = factory.decodeByteArray(buf, 0, buf.length);
                map.put(TEXT_KEY, "数据->" + COUNT);
                map.put(IMAGE_KEY1, bitmap);
                map.put(IMAGE_KEY2, bitmap);
            } catch (Exception e) {
                e.printStackTrace();
            }
            return map;
        }

        @Override
        protected void onPostExecute(Object result) {

            data.add(0,(HashMap<String, Object>) result);
            adapter.notifyDataSetChanged();

            // 设置标签
            listView.setLastUpdatedLabel("最后更新新的时间：" + new Date());

            // 刷新完成
            listView.onRefreshComplete();
            COUNT++;
            if (COUNT >= urls.length) {
                COUNT = 0;
            }
            Toast.makeText(getApplicationContext(), "加载成功", 0).show();
        }
    }

    // 通过URL读取字节数组
    public static byte[] loadRawDataFromURL(String u) throws Exception {
        URL url = new URL(u);
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();

        InputStream is = conn.getInputStream();
        BufferedInputStream bis = new BufferedInputStream(is);

        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        // 缓存2KB
        final int BUFFER_SIZE = 2 * 1024;
        final int EOF = -1;

        int c;
        byte[] buf = new byte[BUFFER_SIZE];

        while (true) {
            c = bis.read(buf);
            if (c == EOF)
                break;

            baos.write(buf, 0, c);
        }

        conn.disconnect();
        is.close();

        byte[] b = baos.toByteArray();
        baos.flush();

        return b;
    }

}