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POAndroid: download images and save them as cache
 

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    <p>I have this Class which downloads images from the web, and I need someone to help me to modify my code below so the downloaded images are saved on the SDCard. Since I take this code from the internet and I'm a newbie, I'm pretty clueless to optimize it for the cache things.</p> <p>I'm open to any kind of solutions. Thanks much.</p> <pre><code>public class ImageThreadLoader { private static final String TAG = "ImageThreadLoader"; // Global cache of images. // Using SoftReference to allow garbage collector to clean cache if needed private final HashMap&lt;String, SoftReference&lt;Bitmap&gt;&gt; Cache = new HashMap&lt;String, SoftReference&lt;Bitmap&gt;&gt;(); private final class QueueItem { public URL url; public ImageLoadedListener listener; } private final ArrayList&lt;QueueItem&gt; Queue = new ArrayList&lt;QueueItem&gt;(); private final Handler handler = new Handler(); // Assumes that this is started from the main (UI) thread private Thread thread; private QueueRunner runner = new QueueRunner();; /** Creates a new instance of the ImageThreadLoader */ public ImageThreadLoader() { thread = new Thread(runner); } /** * Defines an interface for a callback that will handle * responses from the thread loader when an image is done * being loaded. */ public interface ImageLoadedListener { public void imageLoaded(Bitmap imageBitmap ); } /** * Provides a Runnable class to handle loading * the image from the URL and settings the * ImageView on the UI thread. */ private class QueueRunner implements Runnable { public void run() { synchronized(this) { while(Queue.size() &gt; 0) { final QueueItem item = Queue.remove(0); // If in the cache, return that copy and be done if( Cache.containsKey(item.url.toString()) &amp;&amp; Cache.get(item.url.toString()) != null) { // Use a handler to get back onto the UI thread for the update handler.post(new Runnable() { public void run() { if( item.listener != null ) { // NB: There's a potential race condition here where the cache item could get // garbage collected between when we post the runnable and it's executed. // Ideally we would re-run the network load or something. SoftReference&lt;Bitmap&gt; ref = Cache.get(item.url.toString()); if( ref != null ) { item.listener.imageLoaded(ref.get()); } } } }); } else { final Bitmap bmp = readBitmapFromNetwork(item.url); if( bmp != null ) { Cache.put(item.url.toString(), new SoftReference&lt;Bitmap&gt;(bmp)); // Use a handler to get back onto the UI thread for the update handler.post(new Runnable() { public void run() { if( item.listener != null ) { item.listener.imageLoaded(bmp); } } }); } } } } } } /** * Queues up a URI to load an image from for a given image view. * * @param uri The URI source of the image * @param callback The listener class to call when the image is loaded * @throws MalformedURLException If the provided uri cannot be parsed * @return A Bitmap image if the image is in the cache, else null. */ public Bitmap loadImage( final String uri, final ImageLoadedListener listener) throws MalformedURLException { // If it's in the cache, just get it and quit it if( Cache.containsKey(uri)) { SoftReference&lt;Bitmap&gt; ref = Cache.get(uri); if( ref != null ) { return ref.get(); } } QueueItem item = new QueueItem(); item.url = new URL(uri); item.listener = listener; Queue.add(item); // start the thread if needed if( thread.getState() == State.NEW) { thread.start(); } else if( thread.getState() == State.TERMINATED) { thread = new Thread(runner); thread.start(); } return null; } /** * Convenience method to retrieve a bitmap image from * a URL over the network. The built-in methods do * not seem to work, as they return a FileNotFound * exception. * * Note that this does not perform any threading -- * it blocks the call while retrieving the data. * * @param url The URL to read the bitmap from. * @return A Bitmap image or null if an error occurs. */ public static Bitmap readBitmapFromNetwork( URL url ) { InputStream is = null; BufferedInputStream bis = null; Bitmap bmp = null; try { URLConnection conn = url.openConnection(); conn.connect(); is = conn.getInputStream(); bis = new BufferedInputStream(is); bmp = BitmapFactory.decodeStream(bis); } catch (MalformedURLException e) { Log.e(TAG, "Bad ad URL", e); } catch (IOException e) { Log.e(TAG, "Could not get remote ad image", e); } finally { try { if( is != null ) is.close(); if( bis != null ) bis.close(); } catch (IOException e) { Log.w(TAG, "Error closing stream."); } } return bmp; } } </code></pre>
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