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.mysentosa.android.sg.imageloader; import java.io.File; import android.content.Context; import android.content.SharedPreferences; import android.graphics.Bitmap; import android.graphics.Bitmap.CompressFormat; import android.support.v4.util.LruCache; import android.util.Log; import com.mysentosa.android.sg.BuildConfig; import com.mysentosa.android.sg.utils.LogHelper; /** * This class holds our bitmap caches (memory and disk). */ public class ImageCache { private static final String TAG = "ImageCache"; public static final String CACHE_PREFS = "CACHE_PREFS"; // Default memory cache size public static final int DEFAULT_MEM_CACHE_SIZE = 1024 * 1024 * 8; // 8MB // Default disk cache size private static final int DEFAULT_DISK_CACHE_SIZE = 1024 * 1024 * 40; // 20MB // Compression settings when writing images to disk cache private static final CompressFormat DEFAULT_COMPRESS_FORMAT = CompressFormat.PNG; private static final int DEFAULT_COMPRESS_QUALITY = 70; // 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; /** * 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)); } /** * 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); 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 ImageLoaderUtils.getBitmapSize(bitmap); } }; } SharedPreferences mPrefs; mPrefs = context.getSharedPreferences(CACHE_PREFS, Context.MODE_PRIVATE); int CACHE_VERSION_NUMBER = mPrefs.getInt(ImageCacheParams.CACHE_VERSIOON_PREF, -1); if (CACHE_VERSION_NUMBER < ImageCacheParams.CACHE_VERSION) { clearCaches(); // commit database version to shared prefs final SharedPreferences.Editor edit = mPrefs.edit(); edit.clear(); edit.putInt(ImageCacheParams.CACHE_VERSIOON_PREF, ImageCacheParams.CACHE_VERSION); edit.commit(); } } public void clearExpiredCacheImages() { this.mDiskCache.purgeStaleDiskCache(); } public void addBitmapToCache(String data, Bitmap bitmap) { if (data == null || bitmap == null) { return; } // 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) { if (BuildConfig.DEBUG) { LogHelper.d(TAG, "Memory cache hit"); } 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 */ public Bitmap getBitmapFromDiskCache(String data) { if (mDiskCache != null) { return mDiskCache.get(data); } return null; } public void clearCaches() { if (mDiskCache != null) mDiskCache.clearCache(); if (mMemoryCache != null) mMemoryCache.evictAll(); } /** * 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 static int CACHE_VERSION = 1; public static String CACHE_VERSIOON_PREF = "CACHE_VERSIOON_PREF"; public ImageCacheParams(String uniqueName) { this.uniqueName = uniqueName; } } public DiskLruCache getmDiskCache() { return mDiskCache; } }