在android 4.0中使用DiskLruCache不提供openCache方法
有没有人在DiskLruCache上工作？
http://developer.android.com/training/displaying-bitmaps/cache-bitmap.html
提供了一个使用这种caching方法的例子。 但是我观察到4.0源代码中的DiskLruCache的实现没有定义方法。 任何想法如何使用这个？
您可以使用毕加索作为图像加载器。
要么
这就是我所做的：
我使用DiskLruCache （来自Jake Wharton的一个）对象创build了一个名为DiskLruImageCache的类，在开发指南的简单实现（高效显示位图）中也使用了相同的方法：
public class DiskLruImageCache { private DiskLruCache mDiskCache; private CompressFormat mCompressFormat = CompressFormat.JPEG; private int mCompressQuality = 70; private static final int APP_VERSION = 1; private static final int VALUE_COUNT = 1; private static final String TAG = "DiskLruImageCache"; public DiskLruImageCache( Context context,String uniqueName, int diskCacheSize, CompressFormat compressFormat, int quality ) { try { final File diskCacheDir = getDiskCacheDir(context, uniqueName ); mDiskCache = DiskLruCache.open( diskCacheDir, APP_VERSION, VALUE_COUNT, diskCacheSize ); mCompressFormat = compressFormat; mCompressQuality = quality; } catch (IOException e) { e.printStackTrace(); } } private boolean writeBitmapToFile( Bitmap bitmap, DiskLruCache.Editor editor ) throws IOException, FileNotFoundException { OutputStream out = null; try { out = new BufferedOutputStream( editor.newOutputStream( 0 ), Utils.IO_BUFFER_SIZE ); return bitmap.compress( mCompressFormat, mCompressQuality, out ); } finally { if ( out != null ) { out.close(); } } } private File getDiskCacheDir(Context context, String uniqueName) { // Check if media is mounted or storage is built-in, if so, try and use external cache dir // otherwise use internal cache dir final String cachePath = Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState()) || !Utils.isExternalStorageRemovable() ? Utils.getExternalCacheDir(context).getPath() : context.getCacheDir().getPath(); return new File(cachePath + File.separator + uniqueName); } public void put( String key, Bitmap data ) { DiskLruCache.Editor editor = null; try { editor = mDiskCache.edit( key ); if ( editor == null ) { return; } if( writeBitmapToFile( data, editor ) ) { mDiskCache.flush(); editor.commit(); if ( BuildConfig.DEBUG ) { Log.d( "cache_test_DISK_", "image put on disk cache " + key ); } } else { editor.abort(); if ( BuildConfig.DEBUG ) { Log.d( "cache_test_DISK_", "ERROR on: image put on disk cache " + key ); } } } catch (IOException e) { if ( BuildConfig.DEBUG ) { Log.d( "cache_test_DISK_", "ERROR on: image put on disk cache " + key ); } try { if ( editor != null ) { editor.abort(); } } catch (IOException ignored) { } } } public Bitmap getBitmap( String key ) { Bitmap bitmap = null; DiskLruCache.Snapshot snapshot = null; try { snapshot = mDiskCache.get( key ); if ( snapshot == null ) { return null; } final InputStream in = snapshot.getInputStream( 0 ); if ( in != null ) { final BufferedInputStream buffIn = new BufferedInputStream( in, Utils.IO_BUFFER_SIZE ); bitmap = BitmapFactory.decodeStream( buffIn ); } } catch ( IOException e ) { e.printStackTrace(); } finally { if ( snapshot != null ) { snapshot.close(); } } if ( BuildConfig.DEBUG ) { Log.d( "cache_test_DISK_", bitmap == null ? "" : "image read from disk " + key); } return bitmap; } public boolean containsKey( String key ) { boolean contained = false; DiskLruCache.Snapshot snapshot = null; try { snapshot = mDiskCache.get( key ); contained = snapshot != null; } catch (IOException e) { e.printStackTrace(); } finally { if ( snapshot != null ) { snapshot.close(); } } return contained; } public void clearCache() { if ( BuildConfig.DEBUG ) { Log.d( "cache_test_DISK_", "disk cache CLEARED"); } try { mDiskCache.delete(); } catch ( IOException e ) { e.printStackTrace(); } } public File getCacheFolder() { return mDiskCache.getDirectory(); } } Utils源代码是：
public class Utils { public static final int IO_BUFFER_SIZE = 8 * 1024; private Utils() {}; public static boolean isExternalStorageRemovable() { if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.GINGERBREAD) { return Environment.isExternalStorageRemovable(); } return true; } public static File getExternalCacheDir(Context context) { if (hasExternalCacheDir()) { return context.getExternalCacheDir(); } // Before Froyo we need to construct the external cache dir ourselves final String cacheDir = "/Android/data/" + context.getPackageName() + "/cache/"; return new File(Environment.getExternalStorageDirectory().getPath() + cacheDir); } public static boolean hasExternalCacheDir() { return Build.VERSION.SDK_INT >= Build.VERSION_CODES.FROYO; } }
记得放
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
在你的AndroidManifest.xml中
我通过阅读这个代码和Jake Wharton的DiskLruCache中的javadoc来想出这个办法
您还可以使用SimpleDiskCache ，它将DiskLruCache包装在更易于开发的界面中。
我写了一个基于@Platonius发布的这段代码的库。 它包括一些错误修复，例如put（）方法中的“IOExceptions”中的“无法删除文件”。 它使用LRU和磁盘caching： https ： //github.com/felipecs/Android-ImageManager
