android下载网络图片并缓存.docx

1、android下载网络图片并缓存android下载网络图片并缓存分类：图片缓存加载2014-02-12 10:582320人阅读评论(0)收藏举报异步下载网络图片，并提供是否缓存至内存或外部文件的功能异步加载类AsyncImageLoader public void downloadImage(final String url, final ImageCallback callback); public void downloadImage(final String url, final boolean cache2Memory, final ImageCallback callback);

2、public void setCache2File(boolean flag); public void setCachedDir(String dir);图片下载和缓存实现类LoaderImpl1.AsyncImageLoader.javajavaview plaincopy1. packagecom.imagecache;2. 3. importjava.lang.ref.SoftReference;4. importjava.util.HashMap;5. importjava.util.HashSet;6. importjava.util.Map;7. importjava.util.

3、concurrent.ExecutorService;8. importjava.util.concurrent.Executors;9. 10. importandroid.content.Context;11. importandroid.graphics.Bitmap;12. importandroid.os.Handler;13. importandroid.util.Log;14. 15. publicclassAsyncImageLoader16. /保存正在下载的图片URL集合，避免重复下载用17. privatestaticHashSetsDownloadingSet;18.

4、/软引用内存缓存19. privatestaticMapString,SoftReferencesImageCache;20. /图片三种获取方式管理者，网络URL获取、内存缓存获取、外部文件缓存获取21. privatestaticLoaderImplimpl;22. /线程池相关23. privatestaticExecutorServicesExecutorService;24. 25. /通知UI线程图片获取ok时使用26. privateHandlerhandler;27. 28. 29. /*30. *异步加载图片完毕的回调接口31. */32. publicinterfaceIm

5、ageCallback33. /*34. *回调函数35. *parambitmap:maybenull!36. *paramimageUrl37. */38. publicvoidonImageLoaded(Bitmapbitmap,StringimageUrl);39. 40. 41. static42. sDownloadingSet=newHashSet();43. sImageCache=newHashMapString,SoftReference();44. impl=newLoaderImpl(sImageCache);45. 46. 47. publicAsyncImageLo

6、ader(Contextcontext)48. handler=newHandler();49. startThreadPoolIfNecessary();50. 51. StringdefaultDir=context.getCacheDir().getAbsolutePath();52. setCachedDir(defaultDir);53. 54. 55. /*56. *是否缓存图片至/data/data/package/cache/目录57. *默认不缓存58. */59. publicvoidsetCache2File(booleanflag)60. impl.setCache2F

7、ile(flag);61. 62. 63. /*64. *设置缓存路径，setCache2File(true)时有效65. */66. publicvoidsetCachedDir(Stringdir)67. impl.setCachedDir(dir);68. 69. 70. /*开启线程池*/71. publicstaticvoidstartThreadPoolIfNecessary()72. if(sExecutorService=null|sExecutorService.isShutdown()|sExecutorService.isTerminated()73. sExecutor

8、Service=Executors.newFixedThreadPool(3);74. /sExecutorService=Executors.newSingleThreadExecutor();75. 76. 77. 78. /*79. *异步下载图片，并缓存到memory中80. *paramurl81. *paramcallbackseeImageCallbackinterface82. */83. publicvoiddownloadImage(finalStringurl,finalImageCallbackcallback)84. downloadImage(url,true,ca

9、llback);85. 86. 87. /*88. *89. *paramurl90. *paramcache2Memory是否缓存至memory中91. *paramcallback92. */93. publicvoiddownloadImage(finalStringurl,finalbooleancache2Memory,finalImageCallbackcallback)94. if(sDownloadingSet.contains(url)95. Log.i(AsyncImageLoader,#该图片正在下载，不能重复下载！);96. return;97. 98. 99. Bit

10、mapbitmap=impl.getBitmapFromMemory(url);100. if(bitmap!=null)101. if(callback!=null)102. callback.onImageLoaded(bitmap,url);103. 104. else105. /从网络端下载图片106. sDownloadingSet.add(url);107. sExecutorService.submit(newRunnable()108. Override109. publicvoidrun()110. finalBitmapbitmap=impl.getBitmapFromUr

11、l(url,cache2Memory);111. handler.post(newRunnable()112. Override113. publicvoidrun()114. if(callback!=null)115. callback.onImageLoaded(bitmap,url);116. sDownloadingSet.remove(url);117. 118. );119. 120. );121. 122. 123. 124. /*125. *预加载下一张图片，缓存至memory中126. *paramurl127. */128. publicvoidpreLoadNextIm

12、age(finalStringurl)129. /将callback置为空，只将bitmap缓存到memory即可。130. downloadImage(url,null);131. 132. 133. 2.LoaderImpl.javajavaview plaincopy1. packagecom.imagecache;2. 3. importjava.io.FileInputStream;4. importjava.io.FileNotFoundException;5. importjava.io.FileOutputStream;6. importjava.io.IOException;

13、7. importjava.io.InputStream;8. importjava.io.UnsupportedEncodingException;9. importjava.lang.ref.SoftReference;10. import.HttpURLConnection;11. import.URL;12. importjava.security.MessageDigest;13. importjava.security.NoSuchAlgorithmException;14. importjava.util.Map;15. 16. importandroid.graphics.Bi

14、tmap;17. importandroid.graphics.BitmapFactory;18. 19. /*20. *21. *authorAdministrator22. *desc异步加载图片管理器23. *24. */25. publicclassLoaderImpl26. /内存中的软应用缓存27. privateMapString,SoftReferenceimageCache;28. 29. /是否缓存图片至本地文件30. privatebooleancache2FileFlag=false;31. 32. /缓存目录,默认是/data/data/package/cache/目

15、录33. privateStringcachedDir;34. 35. publicLoaderImpl(MapString,SoftReferenceimageCache)36. this.imageCache=imageCache;37. 38. 39. /*40. *是否缓存图片至外部文件41. *paramflag42. */43. publicvoidsetCache2File(booleanflag)44. cache2FileFlag=flag;45. 46. 47. /*48. *设置缓存图片到外部文件的路径49. *paramcacheDir50. */51. publicv

16、oidsetCachedDir(StringcacheDir)52. this.cachedDir=cacheDir;53. 54. 55. /*56. *从网络端下载图片57. *paramurl网络图片的URL地址58. *paramcache2Memory是否缓存(缓存在内存中)59. *returnbitmap图片bitmap结构60. *61. */62. publicBitmapgetBitmapFromUrl(Stringurl,booleancache2Memory)63. Bitmapbitmap=null;64. try65. URLu=newURL(url);66. Ht

17、tpURLConnectionconn=(HttpURLConnection)u.openConnection();67. InputStreamis=conn.getInputStream();68. bitmap=BitmapFactory.decodeStream(is);69. 70. if(cache2Memory)71. /1.缓存bitmap至内存软引用中72. imageCache.put(url,newSoftReference(bitmap);73. if(cache2FileFlag)74. /2.缓存bitmap至/data/data/packageName/cache

18、/文件夹中75. StringfileName=getMD5Str(url);76. StringfilePath=this.cachedDir+/+fileName;77. FileOutputStreamfos=newFileOutputStream(filePath);78. press(Bitmap.CompressFormat.PNG,100,fos);79. 80. 81. 82. is.close();83. conn.disconnect();84. returnbitmap;85. catch(IOExceptione)86. e.printStackTrace();87.

19、returnnull;88. 89. 90. 91. /*92. *从内存缓存中获取bitmap93. *paramurl94. *returnbitmapornull.95. */96. publicBitmapgetBitmapFromMemory(Stringurl)97. Bitmapbitmap=null;98. if(imageCache.containsKey(url)99. synchronized(imageCache)100. SoftReferencebitmapRef=imageCache.get(url);101. if(bitmapRef!=null)102. bi

20、tmap=bitmapRef.get();103. returnbitmap;104. 105. 106. 107. /从外部缓存文件读取108. if(cache2FileFlag)109. bitmap=getBitmapFromFile(url);110. if(bitmap!=null)111. imageCache.put(url,newSoftReference(bitmap);112. 113. 114. returnbitmap;115. 116. 117. /*118. *从外部文件缓存中获取bitmap119. *paramurl120. *return121. */122

21、. privateBitmapgetBitmapFromFile(Stringurl)123. Bitmapbitmap=null;124. StringfileName=getMD5Str(url);125. if(fileName=null)126. returnnull;127. 128. StringfilePath=cachedDir+/+fileName;129. 130. try131. FileInputStreamfis=newFileInputStream(filePath);132. bitmap=BitmapFactory.decodeStream(fis);133. catch(FileNotFoundExceptione)134. e.printStackTrace();135. bitmap=null;136. 137. returnbitmap;138. 139. 140. 141. /*142. *MD5加密14