Java tutorial
/* * Copyright (C) 2012 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.higgses.griffin.cache; import java.io.FileDescriptor; import java.io.FileInputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.lang.ref.SoftReference; import java.util.Collections; import java.util.HashSet; import java.util.Iterator; import java.util.Set; import com.higgses.griffin.core.utils.GriUAndroidVersion; import com.higgses.griffin.log.GinLog; import android.annotation.TargetApi; import android.graphics.Bitmap; import android.graphics.Bitmap.Config; import android.graphics.BitmapFactory; import android.graphics.drawable.BitmapDrawable; import android.os.Build; /** * This class handles disk and memory caching of bitmaps in conjunction with the * {@link ImageWorker} class and its subclasses. Use * * @link com.example.android.displayingbitmaps.util.ImageCache#getInstance(android.support.v4.app.FragmentManager, *com.example.android.displayingbitmaps.util.ImageCache.ImageCacheParams)} to get an instance of this * class, although usually a cache should be added directly to an {@link ImageWorker} by calling * @link ImageWorker#addImageCache(android.support.v4.app.FragmentManager, com.example.android.displayingbitmaps.util.ImageCache.ImageCacheParams)}. */ public class ImageCache extends AbstractCache<String, BitmapDrawable> { private static final String TAG = "ImageCache"; private Set<SoftReference<Bitmap>> mReusableBitmaps; /** * Create a new ImageCache object using the specified parameters. This should not be * called directly by other classes, instead use * * @param cacheParams * The cache parameters to use to initialize the cache * * @link com.example.android.displayingbitmaps.util.ImageCache#getInstance(android.support.v4.app.FragmentManager, *com.example.android.displayingbitmaps.util.ImageCache.ImageCacheParams)} to fetch an ImageCache * instance. */ private ImageCache(CacheParams cacheParams) { super(cacheParams); if (GriUAndroidVersion.hasHoneycomb()) { mReusableBitmaps = Collections.synchronizedSet(new HashSet<SoftReference<Bitmap>>()); } } /** * Return an @link com.example.android.displayingbitmaps.util.ImageCache} instance. A @link com.example.android.displayingbitmaps.util.ImageCache * .RetainFragment} is used to retain the * ImageCache object across configuration changes such as a change in device orientation. * * @param cacheParams * The cache parameters to use if the ImageCache needs instantiation. * * @return An existing retained ImageCache object or a new one if one did not exist */ public static ImageCache getInstance(CacheParams cacheParams) { return new ImageCache(cacheParams); } @Override protected LruCache<String, BitmapDrawable> getLurCache() { return new LruCache<String, BitmapDrawable>(mCacheParams.MEMORY_CACHE_SIZE) { /** * Notify the removed entry that is no longer being cached */ @Override protected void entryRemoved(boolean evicted, String key, BitmapDrawable oldValue, BitmapDrawable newValue) { if (RecyclingBitmapDrawable.class.isInstance(oldValue)) { // The removed entry is a recycling drawable, so notify it // that it has been removed from the memory cache ((RecyclingBitmapDrawable) oldValue).setIsCached(false); } else { // The removed entry is a standard BitmapDrawable if (GriUAndroidVersion.hasHoneycomb()) { // We're running on Honeycomb or later, so add the bitmap // to a SoftReference set for possible use with inBitmap later mReusableBitmaps.add(new SoftReference<Bitmap>(oldValue.getBitmap())); } } } /** * Measure item size in kilobytes rather than units which is more practical * for a bitmap cache */ @Override protected int sizeOf(String key, BitmapDrawable value) { final int bitmapSize = getBitmapSize(value) / 1024; return bitmapSize == 0 ? 1 : bitmapSize; } }; } /** * Adds a bitmap to both memory and disk cache. * * @param data * Unique identifier for the bitmap to store * @param value * The bitmap drawable to store */ public void addBitmapToCache(String data, BitmapDrawable value) { //BEGIN_INCLUDE(add_bitmap_to_cache) if (data == null || value == null) { return; } // Add to memory cache if (mMemoryCache != null) { if (RecyclingBitmapDrawable.class.isInstance(value)) { // The removed entry is a recycling drawable, so notify it // that it has been added into the memory cache ((RecyclingBitmapDrawable) value).setIsCached(true); } mMemoryCache.put(data, value); } synchronized (mDiskCacheLock) { // Add to disk cache if (mDiskLruCache != null) { final String key = hashKeyForDisk(data); OutputStream out = null; try { // DiskLruCache.Snapshot snapshot = mDiskLruCache.get(key); // if (snapshot == null) // { final DiskLruCache.Editor editor = mDiskLruCache.edit(key); if (editor != null) { out = editor.newOutputStream(DISK_CACHE_INDEX); value.getBitmap().compress(mCacheParams.COMPRESS_FORMAT, mCacheParams.COMPRESS_QUALITY, out); editor.commit(); out.close(); } // } // else // { // snapshot.getInputStream(DISK_CACHE_INDEX).close(); // } } catch (Exception e) { GinLog.e(TAG, GinLog.getPrintException(e)); } finally { try { if (out != null) { out.close(); } } catch (IOException e) { } } } } //END_INCLUDE(add_bitmap_to_cache) } /** * Get from memory cache. * * @param data * Unique identifier for which item to get * * @return The bitmap drawable if found in cache, null otherwise */ public BitmapDrawable getBitmapFromMemCache(String data) { //BEGIN_INCLUDE(get_bitmap_from_mem_cache) BitmapDrawable memValue = null; if (mMemoryCache != null) { memValue = mMemoryCache.get(data); } return memValue; //END_INCLUDE(get_bitmap_from_mem_cache) } /** * Get from disk cache. * * @param data * Unique identifier for which item to get * * @return The bitmap if found in cache, null otherwise */ public Bitmap getBitmapFromDiskCache(String data) { //BEGIN_INCLUDE(get_bitmap_from_disk_cache) final String key = hashKeyForDisk(data); Bitmap bitmap = null; synchronized (mDiskCacheLock) { while (mDiskCacheStarting) { try { mDiskCacheLock.wait(); } catch (InterruptedException ignored) { } } if (mDiskLruCache != null) { InputStream inputStream = null; try { final DiskLruCache.Snapshot snapshot = mDiskLruCache.get(key); if (snapshot != null) { inputStream = snapshot.getInputStream(DISK_CACHE_INDEX); if (inputStream != null) { FileDescriptor fd = ((FileInputStream) inputStream).getFD(); // Decode bitmap, but we don't want to sample so give // MAX_VALUE as the target dimensions bitmap = ImageResizer.decodeSampledBitmapFromDescriptor(fd, Integer.MAX_VALUE, Integer.MAX_VALUE, this); } } } catch (final IOException ignored) { } finally { try { if (inputStream != null) { inputStream.close(); } } catch (IOException ignored) { } } } return bitmap; } //END_INCLUDE(get_bitmap_from_disk_cache) } /** * @param options * - BitmapFactory.Options with out* options populated * * @return Bitmap that case be used for inBitmap */ protected Bitmap getBitmapFromReusableSet(BitmapFactory.Options options) { //BEGIN_INCLUDE(get_bitmap_from_reusable_set) Bitmap bitmap = null; if (mReusableBitmaps != null && !mReusableBitmaps.isEmpty()) { synchronized (mReusableBitmaps) { final Iterator<SoftReference<Bitmap>> iterator = mReusableBitmaps.iterator(); Bitmap item; while (iterator.hasNext()) { item = iterator.next().get(); if (null != item && item.isMutable()) { // Check to see it the item can be used for inBitmap if (canUseForInBitmap(item, options)) { bitmap = item; // Remove from reusable set so it can't be used again iterator.remove(); break; } } else { // Remove from the set if the reference has been cleared. iterator.remove(); } } } } return bitmap; //END_INCLUDE(get_bitmap_from_reusable_set) } /** * @param candidate * - Bitmap to check * @param targetOptions * - Options that have the out* value populated * * @return true if <code>candidate</code> can be used for inBitmap re-use with * <code>targetOptions</code> */ @TargetApi(Build.VERSION_CODES.KITKAT) private static boolean canUseForInBitmap(Bitmap candidate, BitmapFactory.Options targetOptions) { //BEGIN_INCLUDE(can_use_for_inbitmap) if (!GriUAndroidVersion.hasKitKat()) { // On earlier versions, the dimensions must match exactly and the inSampleSize must be 1 return candidate.getWidth() == targetOptions.outWidth && candidate.getHeight() == targetOptions.outHeight && targetOptions.inSampleSize == 1; } // From Android 4.4 (KitKat) onward we can re-use if the byte size of the new bitmap // is smaller than the reusable bitmap candidate allocation byte count. int width = targetOptions.outWidth / targetOptions.inSampleSize; int height = targetOptions.outHeight / targetOptions.inSampleSize; int byteCount = width * height * getBytesPerPixel(candidate.getConfig()); return byteCount <= candidate.getAllocationByteCount(); //END_INCLUDE(can_use_for_inbitmap) } /** * Return the byte usage per pixel of a bitmap based on its configuration. * * @param config * The bitmap configuration. * * @return The byte usage per pixel. */ private static int getBytesPerPixel(Config config) { if (config == Config.ARGB_8888) { return 4; } else if (config == Config.RGB_565) { return 2; } else if (config == Config.ARGB_4444) { return 2; } else if (config == Config.ALPHA_8) { return 1; } return 1; } /** * Get the size in bytes of a bitmap in a BitmapDrawable. Note that from Android 4.4 (KitKat) * onward this returns the allocated memory size of the bitmap which can be larger than the * actual bitmap data byte count (in the case it was re-used). * * @param value * * @return size in bytes */ @TargetApi(Build.VERSION_CODES.KITKAT) public static int getBitmapSize(BitmapDrawable value) { Bitmap bitmap = value.getBitmap(); // From KitKat onward use getAllocationByteCount() as allocated bytes can potentially be // larger than bitmap byte count. if (GriUAndroidVersion.hasKitKat()) { return bitmap.getAllocationByteCount(); } if (GriUAndroidVersion.hasHoneycombMR1()) { return bitmap.getByteCount(); } // Pre HC-MR1 return bitmap.getRowBytes() * bitmap.getHeight(); } }