ImageDownloader :
public class ImageDownloader {Map<String,Bitmap> imageCache;
private Bitmap defaultIcon;
public ImageDownloader(){
imageCache = new HashMap<String, Bitmap>();
}
//download function
public void download(String url, ImageView imageView,Bitmap defaultImg) {
if (cancelPotentialDownload(url, imageView)) {
this.defaultIcon=defaultImg;
//Caching code right here
String filename = String.valueOf(url.hashCode());
File f = new File(getCacheDirectory(imageView.getContext()), filename);
// Is the bitmap in our memory cache?
Bitmap bitmap = null;
bitmap = (Bitmap)imageCache.get(f.getPath());
if(bitmap == null){
bitmap = BitmapFactory.decodeFile(f.getPath());
if(bitmap != null){
imageCache.put(f.getPath(), bitmap);
}
}
//No? download it
if(bitmap == null){
BitmapDownloaderTask task = new BitmapDownloaderTask(imageView);
DownloadedDrawable downloadedDrawable = new DownloadedDrawable(task,null,defaultImg);
imageView.setImageDrawable(downloadedDrawable);
imageView.setBackgroundDrawable(null);
task.execute(url);
}else{
//Yes? set the image
imageView.setImageBitmap(bitmap);
imageView.setBackgroundDrawable(null);
}
}
}
//cancel a download (internal only)
private static boolean cancelPotentialDownload(String url, ImageView imageView) {
BitmapDownloaderTask bitmapDownloaderTask = getBitmapDownloaderTask(imageView);
if (bitmapDownloaderTask != null) {
String bitmapUrl = bitmapDownloaderTask.url;
if ((bitmapUrl == null) || (!bitmapUrl.equals(url))) {
bitmapDownloaderTask.cancel(true);
} else {
// The same URL is already being downloaded.
return false;
}
}
return true;
}
//gets an existing download if one exists for the imageview
private static BitmapDownloaderTask getBitmapDownloaderTask(ImageView imageView) {
if (imageView != null) {
Drawable drawable = imageView.getDrawable();
if (drawable instanceof DownloadedDrawable) {
DownloadedDrawable downloadedDrawable = (DownloadedDrawable)drawable;
return downloadedDrawable.getBitmapDownloaderTask();
}
}
return null;
}
//our caching functions
// Find the dir to save cached images
private static File getCacheDirectory(Context context){
String sdState = android.os.Environment.getExternalStorageState();
File cacheDir;
if (sdState.equals(android.os.Environment.MEDIA_MOUNTED)) {
File sdDir = android.os.Environment.getExternalStorageDirectory();
//TODO : Change your diretcory here
cacheDir = new File(sdDir,"data/tac/images");
}
else
cacheDir = context.getCacheDir();
if(!cacheDir.exists())
cacheDir.mkdirs();
return cacheDir;
}
private void writeFile(Bitmap bmp, File f) {
FileOutputStream out = null;
try {
out = new FileOutputStream(f);
bmp.compress(Bitmap.CompressFormat.PNG, 80, out);
} catch (Exception e) {
e.printStackTrace();
}
finally {
try { if (out != null ) out.close(); }
catch(Exception ex) {}
}
}
///////////////////////
//download asynctask
public class BitmapDownloaderTask extends AsyncTask<String, Void, Bitmap> {
private String url;
private final WeakReference<ImageView> imageViewReference;
public BitmapDownloaderTask(ImageView imageView) {
imageViewReference = new WeakReference<ImageView>(imageView);
}
@Override
// Actual download method, run in the task thread
protected Bitmap doInBackground(String... params) {
// params comes from the execute() call: params[0] is the url.
url = (String)params[0];
return downloadBitmap(params[0]);
}
@Override
// Once the image is downloaded, associates it to the imageView
protected void onPostExecute(Bitmap bitmap) {
if (isCancelled()) {
bitmap = null;
}
if (imageViewReference != null) {
ImageView imageView = imageViewReference.get();
BitmapDownloaderTask bitmapDownloaderTask = getBitmapDownloaderTask(imageView);
// Change bitmap only if this process is still associated with it
if (this == bitmapDownloaderTask) {
imageView.setImageBitmap(bitmap);
//cache the image
String filename = String.valueOf(url.hashCode());
File f = new File(getCacheDirectory(imageView.getContext()), filename);
imageCache.put(f.getPath(), bitmap);
writeFile(bitmap, f);
}
}
}
}
// static class DownloadedDrawable extends ColorDrawable {
// private final WeakReference<BitmapDownloaderTask> bitmapDownloaderTaskReference;
//
// public DownloadedDrawable(BitmapDownloaderTask bitmapDownloaderTask) {
// super(Color.TRANSPARENT);
// bitmapDownloaderTaskReference =
// new WeakReference<BitmapDownloaderTask>(bitmapDownloaderTask);
// }
//
// public BitmapDownloaderTask getBitmapDownloaderTask() {
// return bitmapDownloaderTaskReference.get();
// }
// }
private static class DownloadedDrawable extends BitmapDrawable {
private final WeakReference<BitmapDownloaderTask>
bitmapDownloaderTaskReference;
private DownloadedDrawable(BitmapDownloaderTask bitmapDownloaderTask,
Resources resources, Bitmap bitmap) {
super(resources, bitmap); // you'll have to provide these
bitmapDownloaderTaskReference =
new WeakReference<BitmapDownloaderTask>(bitmapDownloaderTask);
}
public BitmapDownloaderTask getBitmapDownloaderTask() {
return bitmapDownloaderTaskReference.get();
}
}
//the actual download code
static Bitmap downloadBitmap(String url) {
url=url.replace(" ", "%20");
HttpParams params = new BasicHttpParams();
params.setParameter(CoreProtocolPNames.PROTOCOL_VERSION, HttpVersion.HTTP_1_1);
HttpClient client = new DefaultHttpClient(params);
final HttpGet getRequest = new HttpGet(url);
try {
HttpResponse response = client.execute(getRequest);
final int statusCode = response.getStatusLine().getStatusCode();
if (statusCode != HttpStatus.SC_OK) {
Log.w("ImageDownloader", "Error " + statusCode + " while retrieving bitmap from " + url);
return null;
}
final HttpEntity entity = response.getEntity();
if (entity != null) {
InputStream inputStream = null;
try {
inputStream = entity.getContent();
final Bitmap bitmap = BitmapFactory.decodeStream(inputStream);
return bitmap;
} finally {
if (inputStream != null) {
inputStream.close();
}
entity.consumeContent();
}
}
} catch (Exception e) {
// Could provide a more explicit error message for IOException or IllegalStateException
getRequest.abort();
Log.w("ImageDownloader", "Error while retrieving bitmap from " + url + e.toString());
} finally {
if (client != null) {
//client.close();
}
}
return null;
}
}
How to use:
ImageDownloader downloader = new ImageDownloader();
downloader.download(stringUrl,
imageViewProfile, defaultImgBitmap);
