Android Jamendo源碼 圖片緩存實現

Android Jamendo源碼 圖片緩存實現 ：

1. package com.teleca.jamendo.util;
3. import java.util.WeakHashMap;
5. import android.graphics.Bitmap;
7. /**
8. * Caches downloaded images, saves bandwidth and user's
9. * packets
10. *
11. * @author Lukasz Wisniewski
12. */
13. public class ImageCache extends WeakHashMap<String, Bitmap> {
15. //WeakHashMap....add by gjican...
16. private static final long serialVersionUID = 1L;
18. public boolean isCached(String url){
19. return containsKey(url) && get(url) != null;
20. }
22. }

在JamendoApplicatin中定義一個全局的getImageCache()來獲得當前應用程序圖片緩存 JamendoApplication.getInstance().getImageCache().put(mTaskUrl, bmp);

然後在每次下載圖片之前先進行判斷，看是否緩存裡存在此圖片，若有則直接顯示，否則調用DownloadTast()去下載

1. public String doInBackground(String... params) {
3. mTaskUrl = params[0];
4. InputStream stream = null;
5. URL imageUrl;
6. Bitmap bmp = null;
8. try {
9. imageUrl = new URL(mTaskUrl);
10. try {
11. stream = imageUrl.openStream();
12. bmp = BitmapFactory.decodeStream(stream);
13. try {
14. if(bmp != null){
15. JamendoApplication.getInstance().getImageCache().put(mTaskUrl, bmp);
16. Log.d(JamendoApplication.TAG, "Image cached "+mTaskUrl);
17. } else {
18. Log.w(JamendoApplication.TAG, "Failed to cache "+mTaskUrl);
19. }
20. } catch (NullPointerException e) {
21. Log.w(JamendoApplication.TAG, "Failed to cache "+mTaskUrl);
22. }
23. } catch (IOException e) {
24. Log.w(JamendoApplication.TAG, "Couldn't load bitmap from url: " + mTaskUrl);
25. } finally {
26. try {
27. if(stream != null){
28. stream.close();
29. }
30. } catch (IOException e) {}
31. }
33. } catch (MalformedURLException e) {
34. e.printStackTrace();
35. }
36. return mTaskUrl;
37. }