學習Android之SimpleAdapter顯示網狀圖片

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此程式主要的知識點是：SimpleAdapter本身是不支援網狀圖片的， 如果在Map.put（a，b）中 b為一個Bitmap，程式不會報紅色字型，而是在控制台輸出綠色的字型，如下

05-10 15:46:45.474: I/System.out(846): resolveUri failed on bad bitmap uri: [email protected]

要想實現顯示網狀圖片其實很簡單，使用SimpleAdapter中的方法simpleAdapter.setViewBinder（）。

simpleAdapter.setViewBinder(new ViewBinder() {@Overridepublic boolean setViewValue(View view, Object data,String textRepresentation) {if (view instanceof ImageView && data instanceof Bitmap) {ImageView iv = (ImageView) view;iv.setImageBitmap((Bitmap) data);return true;}return false;}});

new SimpleAdapter(MainActivity.this,getData(), R.layout.t, new String[] { "images" },new int[] { R.id.ImageVIew_main });

有三個參數view,data,textRepresentation，說說前兩個參數，view 是你自訂布局（如上 R.layout.t）中所有的組件，程式會遍曆一邊布局中的組件，data是你傳的

list<map< , >>（如上getData()方法，返回一個list<map< , >>），程式會遍曆每一項資料。接下來用if（）語句篩選就可以了。

既然是網狀圖片，那就需要許可權

 <uses-permission android:name="android.permission.INTERNET" />

代碼如下：

MainActivity.java

public class MainActivity extends ActionBarActivity {ListView listView;List<Map<String, ?>> data;String str[] = { "",       //自己添加圖片網址 h  t  t  p ://"","","" };@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);listView = (ListView) findViewById(R.id.LV_main);SimpleAdapter simpleAdapter = new SimpleAdapter(MainActivity.this,getData(), R.layout.t, new String[] { "images" },new int[] { R.id.ImageVIew_main });simpleAdapter.setViewBinder(new ViewBinder() {@Overridepublic boolean setViewValue(View view, Object data,String textRepresentation) {if (view instanceof ImageView && data instanceof Bitmap) {ImageView iv = (ImageView) view;iv.setImageBitmap((Bitmap) data);return true;}return false;}});listView.setAdapter(simpleAdapter);}public List<Map<String, ?>> getData() {data = new ArrayList<Map<String, ?>>();for (int i = 0; i < str.length; i++) {Map<String, Object> map = new HashMap<String, Object>();map.put("images", returnBitMap(str[i]));data.add(map);}return data;}public Bitmap returnBitMap(String url) {URL myFileUrl = null;Bitmap bitmap = null;try {myFileUrl = new URL(url);} catch (MalformedURLException e) {e.printStackTrace();}try {HttpURLConnection conn = (HttpURLConnection) myFileUrl.openConnection();conn.setDoInput(true);conn.connect();InputStream is = conn.getInputStream();bitmap = BitmapFactory.decodeStream(is);is.close();} catch (IOException e) {e.printStackTrace();}return bitmap;}}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:orientation="vertical"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    ><ListView     android:id="@+id/LV_main"    android:layout_width="fill_parent"    android:layout_height="fill_parent"></ListView> </LinearLayout>

自訂布局檔案

t.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical" >        <ImageView         android:id="@+id/ImageVIew_main"        android:layout_width="80dp"        android:layout_height="80dp"/></LinearLayout>