Android Remote Image Retrieval and local cache (3)

Obtain data from the cache:

Java code:

1. /**
2. * Retrieving images from the cache
3. */
4. Private Bitmap getBitmapFromCache (Stringurl ){
5. // Obtain it from the mHardBitmapCache cache first
6. Synchronized (mHardBitmapCache ){
7. Final Bitmap bitmap = mHardBitmapCache. get (url );
8. If (bitmap! = Null ){
9. // If it is found, move the element to the beginning of linkedhashmap to ensure that it is finally deleted in the LRU algorithm.
10. MHardBitmapCache. remove (url );
11. MHardBitmapCache. put (url, bitmap );
12. Return bitmap;
13. }
14. }
15. // If mHardBitmapCache cannot be found, find it in mSoftBitmapCache
16. SoftReference <Bitmap> bitmapReference = mSoftBitmapCache. get (url );
17. If (bitmapReference! = Null ){
18. Final Bitmap bitmap = bitmapReference. get ();
19. If (bitmap! = Null ){
20. Return bitmap;
21. } Else {
22. MSoftBitmapCache. remove (url );
23. }
24. }
25. Return null;
26. }

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If the cache does not exist, you can only download it from the server:

Java code:

1. /**
2. * Asynchronous image download
3. */
4. Class ImageDownloaderTask extendsAsyncTask <String, Void, Bitmap> {
5. Private static final int IO_BUFFER_SIZE = 4*1024;
6. Private String url;
7. Private finalWeakReference <ImageView> imageViewReference;
8. Public ImageDownloaderTask (ImageViewimageView ){
9. ImageViewReference = newWeakReference <ImageView> (imageView );
10. }
12. @ Override
13. Protected BitmapdoInBackground (String... params ){
14. Final AndroidHttpClient client = AndroidHttpClient. newInstance ("Android ");
15. Url = params [0];
16. Final HttpGet getRequest = newHttpGet (url );
17. Try {
18. HttpResponse response implements client.exe cute (getRequest );
19. Final int statusCode = response. getStatusLine (). getStatusCode ();
20. If (statusCode! = HttpStatus. SC _ OK ){
21. Log. w (TAG, "An error occurred while downloading images from" + url + !, Error Code: "+ statusCode );
22. Return null;
23. }
24. Final HttpEntity entity = response. getEntity ();
25. If (entity! = Null ){
26. InputStream inputStream = null;
27. OutputStream outputStream = null;
28. Try {
29. InputStream = entity. getContent ();
30. FinalByteArrayOutputStream dataStream = new ByteArrayOutputStream ();
31. OutputStream = newBufferedOutputStream (dataStream, IO_BUFFER_SIZE );
32. Copy (inputStream, outputStream );
33. OutputStream. flush ();
34. Final byte [] data = dataStream. toByteArray ();
35. Final Bitmap bitmap = BitmapFactory. decodeByteArray (data, 0, data. length );
36. Return bitmap;
37. } Finally {
38. If (inputStream! = Null ){
39. InputStream. close ();
40. }
41. If (outputStream! = Null ){
42. OutputStream. close ();
43. }
44. Entity. consumeContent ();
45. }
46. }
47. } Catch (IOException e ){
48. GetRequest. abort ();
49. Log. w (TAG, "I/O errorwhile retrieving bitmap from" + url, e );
50. } Catch (IllegalStateException e ){
51. GetRequest. abort ();
52. Log. w (TAG, "Incorrect URL:" + url );
53. } Catch (Exception e ){
54. GetRequest. abort ();
55. Log. w (TAG, "Error whileretrieving bitmap from" + url, e );
56. } Finally {
57. If (client! = Null ){
58. Client. close ();
59. }
60. }
61. Return null;
62. }

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Series of Android remote image acquisition and local cache (1) Post link http://www.eoeandroid.com/thread-98446-1-1.html
Series of Android remote image acquisition and local cache (2) Post link http://www.eoeandroid.com/thread-98449-1-1.html