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 me.onemobile.client.image; import java.io.File; import android.content.Context; import android.graphics.Bitmap; import android.graphics.Bitmap.CompressFormat; import android.support.v4.app.FragmentActivity; import android.support.v4.util.LruCache; /** * This class holds our bitmap caches (memory and disk). */ public class ImageCache { public static String CACHE_DIR_IMAGES = "images"; // Default memory cache size public static final int DEFAULT_MEM_CACHE_SIZE = 1024 * 1024 * 4; // 4MB // Default disk cache size public static final int DEFAULT_DISK_CACHE_SIZE = 1024 * 1024 * 10; // 10MB // Compression settings when writing images to disk cache private static final CompressFormat DEFAULT_COMPRESS_FORMAT = CompressFormat.PNG; private static final int DEFAULT_COMPRESS_QUALITY = 100; // Constants to easily toggle various caches private static final boolean DEFAULT_MEM_CACHE_ENABLED = true; private static final boolean DEFAULT_DISK_CACHE_ENABLED = true; private static final boolean DEFAULT_CLEAR_DISK_CACHE_ON_START = false; private DiskLruCache mDiskCache; private LruCache<String, Bitmap> mMemoryCache; /** * Initial cache file path * * @param ctx * @param pathName * Unique directory name */ public static void setup(Context ctx, String pathName) { ImageCache.CACHE_DIR_IMAGES = pathName; DiskLruCache.mCacheDir = DiskLruCache.getDiskCacheDir(ctx, ImageCache.CACHE_DIR_IMAGES); if (DiskLruCache.mCacheDir != null) { if (!DiskLruCache.mCacheDir.exists()) { DiskLruCache.mCacheDir.mkdirs(); } } } /** * Creating a new ImageCache object using the specified parameters. * * @param context * The context to use * @param cacheParams * The cache parameters to use to initialize the cache */ public ImageCache(Context context, ImageCacheParams cacheParams) { init(context, cacheParams); } /** * Creating a new ImageCache object using the default parameters. * * @param context * The context to use * @param uniqueName * A unique name that will be appended to the cache directory */ public ImageCache(Context context, String uniqueName) { init(context, new ImageCacheParams(uniqueName)); } public static ImageCache getInstance(Context context) { int fitSize = Utils.getMemCacheSize(context); ImageCacheParams cacheParams = new ImageCacheParams(CACHE_DIR_IMAGES); if (fitSize > 0) { cacheParams.memCacheSize = fitSize; } return new ImageCache(context, cacheParams); } public static ImageCache getInstance(FragmentActivity activity) { return findOrCreateCache(activity, CACHE_DIR_IMAGES); } /** * Find and return an existing ImageCache stored in a {@link RetainFragment} * , if not found a new one is created with defaults and saved to a * {@link RetainFragment}. * * @param activity * The calling {@link FragmentActivity} * @param uniqueName * A unique name to append to the cache directory * @return An existing retained ImageCache object or a new one if one did * not exist. */ public static ImageCache findOrCreateCache(final FragmentActivity activity, final String uniqueName) { ImageCacheParams cacheParams = new ImageCacheParams(uniqueName); int fitSize = Utils.getMemCacheSize(activity); if (fitSize > 0) { cacheParams.memCacheSize = fitSize; } return findOrCreateCache(activity, cacheParams); } /** * Find and return an existing ImageCache stored in a {@link RetainFragment} * , if not found a new one is created using the supplied params and saved * to a {@link RetainFragment}. * * @param activity * The calling {@link FragmentActivity} * @param cacheParams * The cache parameters to use if creating the ImageCache * @return An existing retained ImageCache object or a new one if one did * not exist */ public static ImageCache findOrCreateCache(final FragmentActivity activity, ImageCacheParams cacheParams) { // Search for, or create an instance of the non-UI RetainFragment final RetainFragment mRetainFragment = RetainFragment .findOrCreateRetainFragment(activity.getSupportFragmentManager()); ImageCache imageCache = null; if (mRetainFragment != null) { // See if we already have an ImageCache stored in RetainFragment imageCache = (ImageCache) mRetainFragment.getObject(); } // No existing ImageCache, create one and store it in RetainFragment if (imageCache == null) { imageCache = new ImageCache(activity, cacheParams); if (mRetainFragment != null) { mRetainFragment.setObject(imageCache); } } return imageCache; } /** * Try to find and return an existing ImageCache stored in a * {@link RetainFragment} * * @param activity * @return ImageCache or null */ public static ImageCache tryTofindCache(final FragmentActivity activity) { // Search for, or create an instance of the non-UI RetainFragment RetainFragment mRetainFragment = (RetainFragment) activity.getSupportFragmentManager() .findFragmentByTag(RetainFragment.TAG); ImageCache imageCache = null; if (mRetainFragment != null) { // See if we already have an ImageCache stored in RetainFragment imageCache = (ImageCache) mRetainFragment.getObject(); } return imageCache; } /** * Initialize the cache, providing all parameters. * * @param context * The context to use * @param cacheParams * The cache parameters to initialize the cache */ private void init(Context context, ImageCacheParams cacheParams) { final File diskCacheDir = DiskLruCache.getDiskCacheDir(context, cacheParams.uniqueName); // Set up disk cache if (cacheParams.diskCacheEnabled) { mDiskCache = DiskLruCache.openCache(context, diskCacheDir, cacheParams.diskCacheSize); if (mDiskCache != null) { mDiskCache.setCompressParams(cacheParams.compressFormat, cacheParams.compressQuality); if (cacheParams.clearDiskCacheOnStart) { mDiskCache.clearCache(); } } } // Set up memory cache if (cacheParams.memoryCacheEnabled) { mMemoryCache = new LruCache<String, Bitmap>(cacheParams.memCacheSize) { /** * Measure item size in bytes rather than units which is more * practical for a bitmap cache */ @Override protected int sizeOf(String key, Bitmap bitmap) { return Utils.getBitmapSize(bitmap); } }; } } public void addBitmapToCache(String data, Bitmap bitmap) { if (data == null || bitmap == null) { return; } synchronized (this) { // Add to memory cache if (mMemoryCache != null && mMemoryCache.get(data) == null) { mMemoryCache.put(data, bitmap); } // Add to disk cache if (mDiskCache != null && !mDiskCache.containsKey(data)) { mDiskCache.put(data, bitmap); } } } /** * Get from memory cache. * * @param data * Unique identifier for which item to get * @return The bitmap if found in cache, null otherwise */ public Bitmap getBitmapFromMemCache(String data) { if (mMemoryCache != null) { final Bitmap memBitmap = mMemoryCache.get(data); if (memBitmap != null) { return memBitmap; } } return null; } /** * Get from disk cache. * * @param data * Unique identifier for which item to get * @return The bitmap if found in cache, null otherwise * @deprecated never do that. Cause' return the original image . */ public Bitmap getBitmapFromDiskCache(String data) { if (mDiskCache != null) { return mDiskCache.get(data); } return null; } public String getCacheFile(String data) { if (mDiskCache != null) { return mDiskCache.getCacheFile(data); } return null; } public void clearCaches() { if (mDiskCache != null) { mDiskCache.clearCache(); } if (mMemoryCache != null) { mMemoryCache.evictAll(); } } public void cleanMemCache() { if (mMemoryCache != null) { mMemoryCache.evictAll(); mMemoryCache = null; } if (mDiskCache != null) { mDiskCache.clearLinkedHashMap(); mDiskCache = null; } } /** * A holder class that contains cache parameters. */ public static class ImageCacheParams { public String uniqueName; public int memCacheSize = DEFAULT_MEM_CACHE_SIZE; public int diskCacheSize = DEFAULT_DISK_CACHE_SIZE; public CompressFormat compressFormat = DEFAULT_COMPRESS_FORMAT; public int compressQuality = DEFAULT_COMPRESS_QUALITY; public boolean memoryCacheEnabled = DEFAULT_MEM_CACHE_ENABLED; public boolean diskCacheEnabled = DEFAULT_DISK_CACHE_ENABLED; public boolean clearDiskCacheOnStart = DEFAULT_CLEAR_DISK_CACHE_ON_START; public ImageCacheParams(String uniqueName) { this.uniqueName = uniqueName; } } public void deleteCacheFile(String key) { if (mDiskCache != null) { mDiskCache.deleteCache(key); } } }