Android : Download images from server and save them on device cache

问题

I have gone through following links

enter link description here

and i have followed the following tutorial to do cache the images after loading it from server

enter link description here

and my code segment is :

private Bitmap getBitmap(String url) {
//      PhotoToLoad photoToLoad = new PhotoToLoad(url, new ImageView(a));
//      String filename = photoToLoad.url;
        //String filename = url;
        String filename = String.valueOf(url.hashCode());
        Log.v("TAG FILE :", filename);
        File f = new File(cacheDir, filename);
        // Is the bitmap in our cache?
        Bitmap bitmap = BitmapFactory.decodeFile(f.getPath());
        if (bitmap != null)
            return bitmap;
        else {
            // Nope, have to download it
            try {
                bitmap = BitmapFactory.decodeStream(new URL(url)
                        .openConnection().getInputStream());
                // save bitmap to cache for later
                writeFile(bitmap, f);
                return bitmap;
            } catch (FileNotFoundException ex) {
                ex.printStackTrace();
                Log.v("FILE NOT FOUND", "FILE NOT FOUND");
                return null;
            }catch (Exception e) {
                // TODO: handle exception
                e.printStackTrace();
                return null;
            }
        }
    }

    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) {
            }
        }
    }

I am getting FileNotFoundException :

11-12 15:19:25.495: VERBOSE/cacheDir(266): /sdcard/data/BalajeeBazaar

11-12 15:19:26.035: VERBOSE/TAG FILE :(266): -951166081

11-12 15:19:26.315: WARN/System.err(266): java.io.FileNotFoundException: /sdcard/data/BalajeeBazaar/-951166081

11-12 15:19:26.315: WARN/System.err(266):     at org.apache.harmony.luni.platform.OSFileSystem.open(OSFileSystem.java:231)

11-12 15:19:26.315: WARN/System.err(266):     at java.io.FileOutputStream.<init>(FileOutputStream.java:96)

11-12 15:19:26.315: WARN/System.err(266):     at java.io.FileOutputStream.<init>(FileOutputStream.java:69)

11-12 15:19:26.315: WARN/System.err(266):     at com.ecommerce.balajeebazaar.CacheImages.writeFile(CacheImages.java:160)

11-12 15:19:26.315: WARN/System.err(266):     at com.ecommerce.balajeebazaar.CacheImages.getBitmap(CacheImages.java:142)

11-12 15:19:26.315: WARN/System.err(266):     at com.ecommerce.balajeebazaar.CacheImages.access$0(CacheImages.java:125)

11-12 15:19:26.315: WARN/System.err(266):     at com.ecommerce.balajeebazaar.CacheImages$PhotosLoader.run(CacheImages.java:77)

11-12 15:19:26.325: WARN/dalvikvm(266): threadid=17: thread exiting with uncaught exception (group=0x4001aa28)

11-12 15:19:26.325: ERROR/AndroidRuntime(266): Uncaught handler: thread Thread-10 exiting due to uncaught exception

11-12 15:19:26.325: ERROR/AndroidRuntime(266): java.lang.ClassCastException: android.graphics.Bitmap

11-12 15:19:26.325: ERROR/AndroidRuntime(266):     at com.ecommerce.balajeebazaar.CacheImages$PhotosLoader.run(CacheImages.java:79)

Please guide me how to resolve this ?

Thanks~

回答1:

Are you properly defining the directory name?

Maybe you didn't declare the directory name properly...

So, can you please check that it's all right ??

 //Find the dir to save cached images
    if (android.os.Environment.getExternalStorageState().equals(android.os.Environment.MEDIA_MOUNTED))
        cacheDir=new File(android.os.Environment.getExternalStorageDirectory(),"YourDirectoryName");
    else
        cacheDir=context.getCacheDir();
    if(!cacheDir.exists())
        cacheDir.mkdirs();
}

Check your class and make sure your path is right or anything else and tell me after.

回答2:

In the stack trace it shows a file not found exception. I've seen this happen when the file folder doesn't exist. did you create it first. alternatively, you can use the cache or external folder mentioned above.

来源：https://stackoverflow.com/questions/8103729/android-download-images-from-server-and-save-them-on-device-cache

标签

android

caching

hashmap

filenotfoundexception