在Android 4.0的使用DiskLruCache不提供openCache方法 [英] Using DiskLruCache in android 4.0 does not provide for openCache method
问题描述
对DiskLruCache人的工作？
Have anyone worked on DiskLruCache?
<一个href="http://developer.android.com/training/displaying-bitmaps/cache-bitmap.html">http://developer.android.com/training/displaying-bitmaps/cache-bitmap.html
提供了一种使用此高速缓存方法的一个例子。但我观察4.0源$ C $ c中的实现DiskLruCache没有定义的方法。不知道如何使用它？
provides an example of using this caching method. But i observe the implementation for DiskLruCache in 4.0 source code does not have defined methods. Any idea how to use this?
推荐答案
您可以使用毕加索的图像加载器。
You can use Picasso as image loader.
或
这是我做的：
我创建了一个名为DiskLruImageCache与DiskLruCache （由杰克沃顿商学院之一）类对象和简单的实现同样的方法在开发指南（有效显示位图）：
I created a class named DiskLruImageCache with a DiskLruCache (the one from Jake Wharton) object and the same methods in the simple implementation on the dev guide (displaying bitmaps efficiently):
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的源$ C $ c是：
Utils source code is:
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;
}
}
记得把
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
在你的AndroidManifest.xml
on your AndroidManifest.xml
我想通了，这样通过阅读<一个href="http://grep$c$c.com/file_/repo1.maven.org/maven2/com.integralblue/htt$p$psponsecache/1.0.0/com/integralblue/htt$p$psponsecache/compat/libcore/net/http/Htt$p$psponseCache.java/?v=source">this code 和杰克沃顿商学院的DiskLruCache的Javadoc
I figured out this way by reading this code and the javadoc from Jake Wharton's DiskLruCache
这篇关于在Android 4.0的使用DiskLruCache不提供openCache方法的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
