• 图片缓存处理


    public class ImageLoaders {
    
        String str = new String();
    
        MemoryCache memoryCache = new MemoryCache();
        FileCache fileCache;
        public static Bitmap bitmap;
        private Map<ImageView, String> imageViews = Collections
                .synchronizedMap(new HashMap<ImageView, String>());
        ArrayList<String> urllist = new ArrayList<String>();
    
        public ImageLoaders(Context context) {
    
            photoLoaderThread.setPriority(Thread.NORM_PRIORITY - 1);
    
            fileCache = new FileCache(context);
        }
    
        final int stub_id = R.drawable.icon;
    
        public void DisplayImage(String url, Activity activity, ImageView imageView) {
            imageViews.put(imageView, url);
    
            urllist.add(url);
    
            if (urllist.size() > 1) {
                Iterator it = urllist.iterator();
                int i = 0;
                while (it.hasNext()) {
    
                    String ss = (String) it.next();
    
    
                    if (i < urllist.size() - 1) {
                        if (memoryCache.get(ss) != null
                                && !memoryCache.get(ss).isRecycled()) {
    
                            Bitmap bit = memoryCache.get(ss);
    
                            bit = null;
    
                        }
    
                    }
    
                    i++;
                }
                urllist.clear();
            }
    
            bitmap = memoryCache.get(url);
    
            if (bitmap != null) {
    
                imageView.setImageBitmap(bitmap);
    
            } else {
                queuePhoto(url, activity, imageView);
                imageView.setImageResource(stub_id);
            }
    
        }
    
        private void queuePhoto(String url, Activity activity, ImageView imageView) {
            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(30000);
                conn.setReadTimeout(30000);
                InputStream is = conn.getInputStream();
                OutputStream os = new FileOutputStream(f);
                com.monsou.photography.publicmethod.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);
    
                // Find the correct scale value. It should be the power of 2.
                final int REQUIRED_SIZE = 240;
                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;
                }
    
                // decode with inSampleSize
                BitmapFactory.Options 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);
                    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();
        }
    
    }

    在适配器中调用

    class GalleryAdapter extends BaseAdapter {
            Context c;
            private ImageLoaders imageLoader;
    
            public GalleryAdapter(Context c) {
                imageLoader = new ImageLoaders(c);
                this.c = c;
            }
    
            @Override
            public int getCount() {
                return productList.getAllItems().size();
            }
    
            @Override
            public Object getItem(int position) {
                return productList.getAllItems().get(position);
            }
    
            @Override
            public long getItemId(int position) {
                return position;
            }
    
            @Override
            public View getView(int position, View convertView, ViewGroup parent) {
                ViewHolder holder = null;
                if (convertView == null) {
                    holder = new ViewHolder();
                    convertView = LayoutInflater.from(c).inflate(
                            R.layout.product_tiem_01, parent, false);
                    holder.imagerView = (ImageView) convertView
                            .findViewById(R.id.imageView1);
                    convertView.setTag(holder);
                } else {
                    holder = (ViewHolder) convertView.getTag();
                }
                String str_iv = productList.getItem(position).getSmallimg();
                imageLoader.DisplayImage(str_iv, ProductActivity.this, holder.imagerView);
                return convertView;
            }
    
        }
    
        public static class ViewHolder {
            ImageView imagerView;
        }
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  • 原文地址:https://www.cnblogs.com/yangcong/p/3326655.html
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