我正在使用imageLoader类从url载入图像.但是这些图像都是通过名为LazyList的文件夹名存储在图库中.它需要高达40-100 mb的内存.但是我不想加载该图像,因为用户可能会感到不适.对不起,英文不好
一切工作正常,但它在画廊中创建一个文件夹,并显示我的应用程序正在使用的所有图像.所以我觉得用户会感到不舒服的我的应用程序.
这是我的图像加载器的代码,并且它连接几个其他类甚至
public class ImageLoader { MemoryCache memoryCache = new MemoryCache(); FileCache fileCache; private Map<ImageView,String> imageViews = Collections .synchronizedMap(new WeakHashMap<ImageView,String>()); ExecutorService executorService; public ImageLoader(Context context) { fileCache = new FileCache(context); executorService = Executors.newFixedThreadPool(5); } final int stub_id = R.drawable.abs__ab_bottom_transparent_light_holo; public void DisplayImage(String url,ImageView imageView) { imageViews.put(imageView,url); Bitmap bitmap = memoryCache.get(url); if (bitmap != null) imageView.setImageBitmap(bitmap); else { queuePhoto(url,imageView); imageView.setImageResource(stub_id); } } private void queuePhoto(String url,ImageView imageView) { PhotoToLoad p = new PhotoToLoad(url,imageView); executorService.submit(new PhotosLoader(p)); } 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); conn.setInstanceFollowRedirects(true); 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); // Find the correct scale value. It should be the power of 2. final int required_SIZE = 100; 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),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; } } class PhotosLoader implements Runnable { PhotoToLoad photoToLoad; PhotosLoader(PhotoToLoad photoToLoad) { this.photoToLoad = photoToLoad; } @Override public void run() { if (imageViewReused(photoToLoad)) return; Bitmap bmp = getBitmap(photoToLoad.url); memoryCache.put(photoToLoad.url,bmp); if (imageViewReused(photoToLoad)) return; BitmapDisplayer bd = new BitmapDisplayer(bmp,photoToLoad); Activity a = (Activity) photoToLoad.imageView.getContext(); a.runOnUiThread(bd); } } boolean imageViewReused(PhotoToLoad photoToLoad) { String tag = imageViews.get(photoToLoad.imageView); if (tag == null || !tag.equals(photoToLoad.url)) return true; return false; } // Used to display bitmap in the UI thread class BitmapDisplayer implements Runnable { Bitmap bitmap; PhotoToLoad photoToLoad; public BitmapDisplayer(Bitmap b,PhotoToLoad p) { bitmap = b; photoToLoad = p; } public void run() { if (imageViewReused(photoToLoad)) return; if (bitmap != null) photoToLoad.imageView.setImageBitmap(bitmap); else photoToLoad.imageView.setImageResource(stub_id); } } public void clearCache() { memoryCache.clear(); fileCache.clear(); } }
解决方法
我通过更改我的FileCache类及其目标文件夹得到我的解决方案
public class FileCache { private File cacheDir; private File nomediaFile; String NOMEDIA = " .nomedia"; public FileCache(Context context) { // Find the dir to save cached images if (android.os.Environment.getExternalStorageState().equals( android.os.Environment.MEDIA_MOUNTED)) { cacheDir = new File(Environment.getExternalStorageDirectory() + "/mydir"); if (cacheDir.mkdir()) { nomediaFile = new File( Environment.getExternalStorageDirectory() + "/mydir/" + NOMEDIA); if (!nomediaFile.exists()) { try { nomediaFile.createNewFile(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } } else { cacheDir = context.getCacheDir(); } if (!cacheDir.exists()) cacheDir.mkdirs(); } public File getFile(String url) { // I identify images by hashcode. Not a perfect solution,good for the // demo. // String filename=String.valueOf(url.hashCode()); // Another possible solution (thanks to grantland) @SuppressWarnings("deprecation") String filename = URLEncoder.encode(url); File f = new File(cacheDir,filename); return f; } public void clear() { File[] files = cacheDir.listFiles(); if (files == null) return; for (File f : files) f.delete(); } }