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我使用Fedors實現延遲加載圖像。但有時，listview中的第一個項目會獲得與列表中最後一個可見項目相同的圖像。所有其他項目獲得正確的圖像。如果我開始在列表中滾動，則第一個項目會更新爲正確的圖像。在我的日誌中，我可以看到ImageView具有相同的toString輸出，所以這一定是我猜的問題：Fedors Lazylist有時會顯示相同的圖像
DEBUG/ImageLoader（6168）：Bitmap：[email protected] ImageView：android.widget。 ImageView的@ 463c1078
DEBUG/ImageLoader的（6168）：位圖：[email protected] ImageView的：[email protected]
public class AdapterPropertyFavouritesList extends ArrayAdapter<Property> {
private final Activity activity;
private final List<Property> events;
public ImageLoader imageLoader;
public AdapterPropertyFavouritesList(Activity activity, List<Property> objects) {
super(activity, R.layout.favourite_item , objects);
this.activity = activity;
this.events = objects;
App app = (App)activity.getApplication();
imageLoader = app.getImageLoader();
}
public static class ViewHolder{
public TextView address1;
public TextView address2;
public TextView price;
public ImageView image;
public RatingBar ratingBar;
public View event;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View rowView = convertView;
ViewHolder holder;
if(rowView == null)
{
LayoutInflater inflater = activity.getLayoutInflater();
rowView = inflater.inflate(R.layout.favourite_item, null);
holder = new ViewHolder();
holder.address1 = (TextView)rowView.findViewById(R.id.address1);
holder.address2 = (TextView)rowView.findViewById(R.id.address2);
holder.price = (TextView)rowView.findViewById(R.id.price);
holder.image = (ImageView)rowView.findViewById(R.id.propertyThumbImg);
holder.ratingBar = (RatingBar)rowView.findViewById(R.id.ratingbar_1);
holder.event = (View)rowView.findViewById(R.id.event);
}
else
holder=(ViewHolder)rowView.getTag();
final Property p = events.get(position);
if (p != null)
{
holder.address1.setText(p.getStreetName());
holder.address2.setText(p.getZipcodeCountry());
holder.price.setText(ViewHelper.getFormatedMoneyValue(p.price));
holder.ratingBar.setRating(p.getTotalRating());
String url = p.getImage(0);
if(url!=null)
{
imageLoader.DisplayImage(url, activity, holder.image);
}
else
{
holder.image.setImageResource(R.drawable.no_photo_available);
}
rowView.setTag(holder);
}
if(p.hasEvents())
{
holder.event.setVisibility(View.VISIBLE);
}
else
{
holder.event.setVisibility(View.GONE);
}
return rowView;
}
}
public class ImageLoader{
private static final String TAG = ImageLoader.class.getSimpleName();
private boolean scaleImage = false;
MemoryCache memoryCache = new MemoryCache();
FileCache fileCache;
private Map<ImageView, String> imageViews = Collections.synchronizedMap(new WeakHashMap<ImageView, String>());
public ImageLoader(Context context)
{
// Make the background thead low priority. This way it will not affect
// the UI performance
photoLoaderThread.setPriority(Thread.NORM_PRIORITY - 1);
fileCache = new FileCache(context);
}
private final int stub_id = R.drawable.loading_1;
public void DisplayImage(String url, Activity activity, ImageView imageView)
{
imageViews.put(imageView, url);
Bitmap bitmap = memoryCache.get(url);
if (bitmap != null)
{
imageView.setImageBitmap(bitmap);
if(App.LOG_ON)
{
App.log(TAG, "Bitmap: "+bitmap+" ImageView: "+imageView);
}
}
else
{
queuePhoto(url, activity, imageView);
imageView.setImageResource(stub_id);
if(App.LOG_ON)
{
App.log(TAG, "------------------------");
App.log(TAG, "queuePhoto. Set default image on ImageView: "+imageView);
App.log(TAG, "queuePhoto. url: "+url);
App.log(TAG, "------------------------");
}
}
}
public boolean hasAllImagesCached(List<String> urls)
{
boolean found = false;
for(int i = 0; i < urls.size() && !found; i++)
{
String url = urls.get(i);
if(!memoryCache.containsImage(url))
{
found = true;
}
}
return !found;
}
private void queuePhoto(String url, Activity activity, ImageView imageView)
{
// This ImageView may be used for other images before. So there may be
// some old tasks in the queue. We need to discard them.
photosQueue.Clean(imageView);
PhotoToLoad p = new PhotoToLoad(url, imageView);
synchronized (photosQueue.photosToLoad)
{
photosQueue.photosToLoad.push(p);
photosQueue.photosToLoad.notifyAll();
}
// start thread if it's not started yet
if (photoLoaderThread.getState() == Thread.State.NEW)
photoLoaderThread.start();
}
private Bitmap getBitmap(String url)
{
File f = fileCache.getFile(url);
// from SD cache
Bitmap b = decodeFile(f);
if (b != null)
return b;
// from web
try
{
Bitmap bitmap = null;
URL imageUrl = new URL(url);
HttpURLConnection conn = (HttpURLConnection) imageUrl.openConnection();
conn.setConnectTimeout(8000);
conn.setReadTimeout(8000);
InputStream is = conn.getInputStream();
OutputStream os = new FileOutputStream(f);
Utils.CopyStream(is, os);
os.close();
bitmap = decodeFile(f);
return bitmap;
} catch (Exception ex)
{
ex.printStackTrace();
return null;
}
}
// decodes image and scales it to reduce memory consumption
private Bitmap decodeFile(File f)
{
try
{
// decode image size
BitmapFactory.Options o = new BitmapFactory.Options();
o.inJustDecodeBounds = true;
BitmapFactory.decodeStream(new FileInputStream(f), null, o);
BitmapFactory.Options o2 = null;
// decode with inSampleSize
if (scaleImage)
{
// Find the correct scale value. It should be the power of 2.
final int REQUIRED_SIZE = 70;
int width_tmp = o.outWidth, height_tmp = o.outHeight;
int scale = 1;
while (true)
{
if (width_tmp/2 < REQUIRED_SIZE || height_tmp/2 < REQUIRED_SIZE)
break;
width_tmp /= 2;
height_tmp /= 2;
scale *= 2;
}
o2 = new BitmapFactory.Options();
o2.inSampleSize = scale;
}
return BitmapFactory.decodeStream(new FileInputStream(f), null, o2);
} catch (FileNotFoundException e)
{
}
return null;
}
// Task for the queue
private class PhotoToLoad
{
public String url;
public ImageView imageView;
public PhotoToLoad(String u, ImageView i)
{
url = u;
imageView = i;
}
}
PhotosQueue photosQueue = new PhotosQueue();
public void stopThread()
{
photoLoaderThread.interrupt();
}
// stores list of photos to download
class PhotosQueue
{
private Stack<PhotoToLoad> photosToLoad = new Stack<PhotoToLoad>();
// removes all instances of this ImageView
public void Clean(ImageView image)
{
for (int j = 0; j < photosToLoad.size();)
{
if (photosToLoad.get(j).imageView == image)
{
photosToLoad.remove(j);
if(App.LOG_ON)
{
App.log(TAG, "photo removed");
}
}
else
{
++j;
}
}
}
}
class PhotosLoader extends Thread
{
public void run()
{
try
{
while (true)
{
// thread waits until there are any images to load in the
// queue
if (photosQueue.photosToLoad.size() == 0)
synchronized (photosQueue.photosToLoad)
{
photosQueue.photosToLoad.wait();
}
if (photosQueue.photosToLoad.size() != 0)
{
PhotoToLoad photoToLoad;
synchronized (photosQueue.photosToLoad)
{
photoToLoad = photosQueue.photosToLoad.pop();
}
Bitmap bmp = getBitmap(photoToLoad.url);
memoryCache.put(photoToLoad.url, bmp);
String tag = imageViews.get(photoToLoad.imageView);
if (tag != null && tag.equals(photoToLoad.url))
{
BitmapDisplayer bd = new BitmapDisplayer(bmp, photoToLoad.imageView);
Activity a = (Activity) photoToLoad.imageView.getContext();
a.runOnUiThread(bd);
}
}
if (Thread.interrupted())
break;
}
} catch (InterruptedException e)
{
// allow thread to exit
}
}
}
PhotosLoader photoLoaderThread = new PhotosLoader();
// Used to display bitmap in the UI thread
class BitmapDisplayer implements Runnable
{
Bitmap bitmap;
ImageView imageView;
public BitmapDisplayer(Bitmap b, ImageView i)
{
bitmap = b;
imageView = i;
}
public void run()
{
if (bitmap != null)
imageView.setImageBitmap(bitmap);
else
imageView.setImageResource(stub_id);
}
}
public void clearCache()
{
memoryCache.clear();
fileCache.clear();
}
public synchronized boolean isScaleImage()
{
return scaleImage;
}
public synchronized void setScaleImage(boolean scaleImage)
{
this.scaleImage = scaleImage;
}
}
所有圖像都有相同的圖像大小400x300。 –