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）

<?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>

item.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>

activity_main.xml

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;
}

}