Use custom items, adapters, AsyncTask, and third-party open-source framework PullToRefresh to implement a custom drop-down list (load images from the network and display the ImageView in the item ),

Use custom items, adapters, AsyncTask, and third-party open-source framework PullToRefresh to implement a custom drop-down list (load images from the network and display the ImageView in the item ),

AsyncTask Usage Details: http://www.cnblogs.com/zzw1994/p/4959949.html

Drop-down open-source framework PullToRefresh usage and download details: http://www.cnblogs.com/zzw1994/p/4992194.html

The specific implementation code is as follows:

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 <TextView15 android: id = "@ + id/textView" 16 android: layout_width = "wrap_content" 17 android: layout_height = "wrap_content" 18 android: layout_alignBottom = "@ + id/imageView1" 19 android: Photo = "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 <ImageView28 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; 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 // set to refresh 60 listView when sliding down. setMode (Mode. PULL_FROM_START); 61 // supports drop-down and top-up listView. setMode (Mode. BOTH); 62 63 // set listening 64 listView. setOnRefreshListener (new OnRefreshListener <ListView> () {65 66 @ Override 67 public void onRefresh (PullToRefreshBase <ListView> refreshView) {68 // complete the business logic 69 new myasynctask(cmd.exe cute (); 70} 71}); 72 73 adapter = new MyAdapter (this, R. layout. item); 74 listView. setAdapter (adapter); 75 76 // you can specify the 77 TextView textView = new TextView (this); 78. setText ("Please pull down and refresh"); 79 listView. setEmptyView (textView); 80} 81 82 // custom Item display parameter settings in the Adapter operation 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 @ Override100 public HashMap <String, Object> getItem (int position) {101 102 return data. get (position); 103} 104 105 @ Override106 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 // a series of delayed operations such as networking operate 132 private class MyAsyncTask extends AsyncTask {133 134 @ Override135 protected void onPreExecute () in AsyncTask () {136 // start to refresh the 137 listView. setRefreshing (); 138} 139 140 @ Override141 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, "data->" + 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 @ Override157 protected void onPostExecute (Object result) {158 159 data. add (0, (HashMap <String, Object>) result); 160 adapter. notifyDataSetChanged (); 161 162 // set the tag 163 listView. setLastUpdatedLabel ("Last updated time:" + new Date (); 164 165 // refresh completed 166 listView. onRefreshComplete (); 167 COUNT ++; 168 if (COUNT> = urls. length) {169 COUNT = 0; 170} 171 Toast. makeText (getApplicationContext (), "loaded successfully", 0 ). show (); 172} 173} 174 175 // read byte array 176 public static byte [] loadRawDataFromURL (String u) through URL) 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 // cache 2KB185 final int BUFFER_SIZE = 2*1024; 186 final int EOF =-1; 187 188 int c; 189 byte [] buf = new byte [BUFFER_SIZE]; 190 191 192 while (true) {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}