使用自定義的item、Adapter和AsyncTask、第三方開源框架PullToRefresh聯合使用實現自定義的下拉列表（從網絡加載圖片顯示在item中的ImageView），

使用自定義的item、Adapter和AsyncTask、第三方開源框架PullToRefresh聯合使用實現自定義的下拉列表（從網絡加載圖片顯示在item中的ImageView），

AsyncTask使用方法詳情：http://www.cnblogs.com/zzw1994/p/4959949.html

下拉開源框架PullToRefresh使用方法和下載詳情：http://www.cnblogs.com/zzw1994/p/4992194.html

具體實現的代碼如下：

item.xml：

1 <?xml version="1.0" encoding="utf-8"?> 2 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 3 android:layout_width="match_parent" 4 android:layout_height="match_parent" 5 > 6 7 <ImageView 8 android:id="@+id/imageView1" 9 android:layout_width="50dp" 10 android:layout_height="50dp" 11 android:layout_alignParentLeft="true" 12 android:src="@drawable/ic_launcher" /> 13 14 <TextView 15 android:id="@+id/textView" 16 android:layout_width="wrap_content" 17 android:layout_height="wrap_content" 18 android:layout_alignBottom="@+id/imageView1" 19 android:layout_alignParentTop="true" 20 android:layout_toLeftOf="@+id/imageView2" 21 android:layout_toRightOf="@+id/imageView1" 22 android:gravity="center" 23 android:text="TextView" 24 android:textColor="@android:color/holo_red_light" 25 android:textSize="30sp" /> 26 27 <ImageView 28 android:id="@+id/imageView2" 29 android:layout_width="50dp" 30 android:layout_height="50dp" 31 android:layout_alignParentRight="true" 32 android:layout_alignParentTop="true" 33 android:src="@drawable/ic_launcher" /> 34 35 </RelativeLayout> item.xml

activity_main.xml:

1 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 2 xmlns:tools="http://schemas.android.com/tools" 3 android:layout_width="match_parent" 4 android:layout_height="match_parent" 5 tools:context="com.zzw.testpulltorefresh.MainActivity" > 6 7 <com.handmark.pulltorefresh.library.PullToRefreshListView 8 android:id="@+id/listView" 9 android:layout_width="match_parent" 10 android:layout_height="match_parent" /> 11 12 </RelativeLayout> activity_main.xml

MainActivity.java:

  1 package com.zzw.testpulltorefresh;
  2 
  3 import java.io.BufferedInputStream;
  4 import java.io.ByteArrayOutputStream;
  5 import java.io.InputStream;
  6 import java.net.HttpURLConnection;
  7 import java.net.URL;
  8 import java.util.ArrayList;
  9 import java.util.Date;
 10 import java.util.HashMap;
 11 
 12 import com.handmark.pulltorefresh.library.PullToRefreshBase;
 13 import com.handmark.pulltorefresh.library.PullToRefreshBase.Mode;
 14 import com.handmark.pulltorefresh.library.PullToRefreshBase.OnRefreshListener;
 15 import com.handmark.pulltorefresh.library.PullToRefreshListView;
 16 
 17 import android.app.Activity;
 18 import android.content.Context;
 19 import android.graphics.Bitmap;
 20 import android.graphics.BitmapFactory;
 21 import android.graphics.Color;
 22 import android.os.AsyncTask;
 23 import android.os.Bundle;
 24 import android.view.LayoutInflater;
 25 import android.view.View;
 26 import android.view.ViewGroup;
 27 import android.widget.ArrayAdapter;
 28 import android.widget.ImageView;
 29 import android.widget.ListView;
 30 import android.widget.TextView;
 31 import android.widget.Toast;
 32 
 33 public class MainActivity extends Activity {
 34     private int COUNT = 0;
 35 
 36     private final String IMAGE_KEY1 = "IMAGE_KEY1";
 37     private final String IMAGE_KEY2 = "IMAGE_KEY2";
 38     private final String TEXT_KEY = "TEXT_KEY";
 39 
 40     private PullToRefreshListView listView;
 41     private ArrayList<HashMap<String, Object>> data;
 42     private ArrayAdapter adapter;
 43     private String[] urls = { "http://p1.so.qhimg.com/bdr/_240_/t01829c584b50b68311.jpg",
 44             "http://p2.so.qhimg.com/bdr/_240_/t011c2cd4fe8723bcb2.jpg",
 45             "http://p4.so.qhimg.com/bdr/_240_/t01b11db3c0961b24a9.jpg",
 46             "http://p4.so.qhimg.com/bdr/_240_/t019786092c7b1688b9.jpg",
 47             "http://p4.so.qhimg.com/bdr/_240_/t015b226d64a10097ce.jpg",
 48             "http://p1.so.qhimg.com/bdr/_240_/t01f6c4382c907133ab.jpg" };
 49 
 50     @Override
 51     protected void onCreate(Bundle savedInstanceState) {
 52         super.onCreate(savedInstanceState);
 53         setContentView(R.layout.activity_main);
 54 
 55         data = new ArrayList<HashMap<String, Object>>();
 56 
 57         listView = (PullToRefreshListView) findViewById(R.id.listView);
 58 
 59         // 設置向下滑動時刷新
 60         listView.setMode(Mode.PULL_FROM_START);
 61         // 支持下拉和上拉 listView.setMode(Mode.BOTH);
 62 
 63         // 設置監聽
 64         listView.setOnRefreshListener(new OnRefreshListener<ListView>() {
 65 
 66             @Override
 67             public void onRefresh(PullToRefreshBase<ListView> refreshView) {
 68                 // 在這完成業務邏輯
 69                 new MyAsyncTask().execute();
 70             }
 71         });
 72 
 73         adapter = new MyAdapter(this, R.layout.item);
 74         listView.setAdapter(adapter);
 75 
 76         // 設置如果數據為空的時候顯示什麼
 77         TextView textView = new TextView(this);
 78         textView.setText("請下拉刷新");
 79         listView.setEmptyView(textView);
 80     }
 81 
 82     //自定義的Item顯示參數設置在Adapter中操作
 83     private class MyAdapter extends ArrayAdapter {
 84 
 85         private LayoutInflater inflater;
 86         private int item;
 87 
 88         public MyAdapter(Context context, int resource) {
 89             super(context, resource);
 90             inflater = LayoutInflater.from(context);
 91             this.item = resource;
 92         }
 93 
 94         @Override
 95         public int getCount() {
 96             return data.size();
 97         }
 98 
 99         @Override
100         public HashMap<String, Object> getItem(int position) {
101 
102             return data.get(position);
103         }
104 
105         @Override
106         public View getView(int position, View convertView, ViewGroup parent) {
107             HashMap<String, Object> map = getItem(position);
108 
109             if (convertView == null) {
110                 convertView = inflater.inflate(item, null);
111             }
112 
113             ImageView image1 = (ImageView) convertView.findViewById(R.id.imageView1);
114             ImageView image2 = (ImageView) convertView.findViewById(R.id.imageView2);
115             TextView textView = (TextView) convertView.findViewById(R.id.textView);
116 
117             image1.setImageBitmap((Bitmap) map.get(IMAGE_KEY1));
118             image2.setImageBitmap((Bitmap) map.get(IMAGE_KEY2));
119             textView.setText(map.get(TEXT_KEY) + "");
120 
121             if (position % 2 == 1) {
122                 textView.setTextColor(Color.BLUE);
123             }
124 
125             return convertView;
126         }
127 
128     }
129 
130     
131     //聯網等一系列延時操作在AsyncTask中操作
132     private class MyAsyncTask extends AsyncTask {
133 
134         @Override
135         protected void onPreExecute() {
136             // 開始刷新
137             listView.setRefreshing();
138         }
139 
140         @Override
141         protected Object doInBackground(Object... params) {
142             HashMap<String, Object> map = new HashMap<String, Object>();
143             try {
144                 byte[] buf = loadRawDataFromURL(urls[COUNT]);
145                 BitmapFactory factory = new BitmapFactory();
146                 Bitmap bitmap = factory.decodeByteArray(buf, 0, buf.length);
147                 map.put(TEXT_KEY, "數據->" + COUNT);
148                 map.put(IMAGE_KEY1, bitmap);
149                 map.put(IMAGE_KEY2, bitmap);
150             } catch (Exception e) {
151                 e.printStackTrace();
152             }
153             return map;
154         }
155 
156         @Override
157         protected void onPostExecute(Object result) {
158 
159             data.add(0,(HashMap<String, Object>) result);
160             adapter.notifyDataSetChanged();
161 
162             // 設置標簽
163             listView.setLastUpdatedLabel("最後更新新的時間：" + new Date());
164 
165             // 刷新完成
166             listView.onRefreshComplete();
167             COUNT++;
168             if (COUNT >= urls.length) {
169                 COUNT = 0;
170             }
171             Toast.makeText(getApplicationContext(), "加載成功", 0).show();
172         }
173     }
174 
175     // 通過URL讀取字節數組
176     public static byte[] loadRawDataFromURL(String u) throws Exception {
177         URL url = new URL(u);
178         HttpURLConnection conn = (HttpURLConnection) url.openConnection();
179 
180         InputStream is = conn.getInputStream();
181         BufferedInputStream bis = new BufferedInputStream(is);
182 
183         ByteArrayOutputStream baos = new ByteArrayOutputStream();
184         // 緩存2KB
185         final int BUFFER_SIZE = 2 * 1024;
186         final int EOF = -1;
187 
188         int c;
189         byte[] buf = new byte[BUFFER_SIZE];
190 
191         while (true) {
192             c = bis.read(buf);
193             if (c == EOF)
194                 break;
195 
196             baos.write(buf, 0, c);
197         }
198 
199         conn.disconnect();
200         is.close();
201 
202         byte[] b = baos.toByteArray();
203         baos.flush();
204 
205         return b;
206     }
207 
208 }