[Android] exercise using ListView (2), androidlistview

[Android] exercise using ListView (2), androidlistview

Exercise asynchronous tasks and LrcCache caching

Package com. android. test; import java. io. inputStream; import java.net. httpURLConnection; import java.net. URL; import com. nostra13.universalimageloader. core. imageLoader; import com. nostra13.universalimageloader. core. imageLoaderConfiguration; import com. nostra13.universalimageloader. core. assist. failReason; import com. nostra13.universalimageloader. core. listener. imageLoadingListener; import android. app. activit Y; import android. graphics. bitmap; import android. graphics. bitmapFactory; import android. graphics. drawable. bitmapDrawable; import android. OS. asyncTask; import android. OS. bundle; import android. support. v4.util. lruCache; import android. view. view; import android. view. viewGroup; import android. widget. baseAdapter; import android. widget. imageView; import android. widget. listAdapter; import android. widget. listView; im Port android. widget. textView; public class MainActivity extends Activity {private ListView lv_images; @ Override protected void onCreate (Bundle savedInstanceState) {super. onCreate (savedInstanceState); setContentView (R. layout. activity_main); lv_images = (ListView) findViewById (R. id. lv_images); ImageLoaderConfiguration configuration = ImageLoaderConfiguration. createDefault (this); ImageLoader. getInstan Ce (). init (configuration); ListAdapter adapter = new ImageAdapter (); lv_images.setAdapter (adapter );} /*** adapter * @ author taoshihan **/class ImageAdapter extends BaseAdapter {private LruCache <String, BitmapDrawable> mImageCache; public ImageAdapter () {int maxSize = (int) (Runtime. getRuntime (). maxMemory ()/8); mImageCache = new LruCache <String, BitmapDrawable> (maxSize) {protected int sizeOf (String ke Y, BitmapDrawable drawable) {return drawable. getBitmap (). getByteCount () ;};}}@ Override public View getView (int position, View convertView, ViewGroup parent) {String url = (String) getItem (position); View view; if (convertView! = Null) {view = convertView;} else {view = View. inflate (getApplicationContext (), R. layout. image_item, null);} ImageView imageView = (ImageView) view. findViewById (R. id. TV _image); BitmapDrawable bitmapDrawable = getBitmapFromMemoryCache (url); if (bitmapDrawable! = Null) {// read the cached image imageView. setImageDrawable (bitmapDrawable);} else {// read network image ImageWorkerTask task = new ImageWorkerTask (imageView); task.exe cute (url);} return view ;} /*** read the image from the cache * @ param key * @ return */public BitmapDrawable getBitmapFromMemoryCache (String key) {if (mImageCache. get (key )! = Null) {return mImageCache. get (key) ;}return null;} public void addBitmapToMemoryCache (String key, BitmapDrawable drawable) {if (getBitmapFromMemoryCache (key) = null) {mImageCache. put (key, drawable) ;}@ Override public int getCount () {// TODO Auto-generated method stub return Images. IMAGE_URLS.length ;}@ Override public Object getItem (int position) {return Images. IMAGE_URLS [position];} @ Overrid E public long getItemId (int position) {// TODO Auto-generated method stub return position ;} /*** asynchronous task ** @ author taoshihan **/class ImageWorkerTask extends AsyncTask <String, Void, BitmapDrawable> {private ImageView imageView; public ImageWorkerTask (ImageView imageView) {this. imageView = imageView;} @ Override protected BitmapDrawable doInBackground (String... params) {String imageUrl = params [0]; Bitmap bitmap = downLoadBitmap (imageUrl); BitmapDrawable drawable = new BitmapDrawable (getApplicationContext (). getResources (), bitmap); addBitmapToMemoryCache (imageUrl, drawable); return drawable ;}// download the image private Bitmap downLoadBitmap (String imageUrl) {Bitmap bitmap = null; try {URL url = new URL (imageUrl); HttpURLConnection conn = (HttpURLConnection) url. openConnection (); conn. setConnectTimeout (10000 ); InputStream is = conn. getInputStream (); bitmap = BitmapFactory. decodeStream (is);} catch (Exception e) {} return bitmap;} // The downloaded @ Override protected void onPostExecute (BitmapDrawable result) {if (imageView! = Null & result! = Null) {imageView. setImageDrawable (result) ;}}} static class Images {public final static String [] IMAGE_URLS = new String [] {"http://img.my.csdn.net/uploads/201508/05/1438760758_3497.jpg", "http://img.my.csdn.net/uploads/201508/05/1438760758_6667.jpg", "http://img.my.csdn.net/uploads/201508/05/1438760757_3588.jpg ", "http://img.my.csdn.net/uploads/201508/05/1438760756_3304.jpg", "http://img.my.csdn.net/uploads/201508/05/1438760755_6715.jpeg", "http://img.my.csdn.net/uploads/201508/05/1438760726_5120.jpg", "http://img.my.csdn.net/uploads/201508/05/1438760726_8364.jpg", "http://img.my.csdn.net/uploads/201508/05/1438760725_4031.jpg", "http://img.my.csdn.net/uploads/201508/05/1438760724_9463.jpg", "http://img.my.csdn.net/uploads/201508/05/1438760724_2371.jpg", "http://img.my.csdn.net/uploads/201508/05/1438760707_4653.jpg "};}}