private lateinit var memoryCache: LruCache<String, Bitmap>
override fun onCreate(savedInstanceState: Bundle?) {
...
// Get max available VM memory, exceeding this amount will throw an
// OutOfMemory exception. Stored in kilobytes as LruCache takes an
// int in its constructor.
val maxMemory = (Runtime.getRuntime().maxMemory() / 1024).toInt()
// Use 1/8th of the available memory for this memory cache.
val cacheSize = maxMemory / 8
memoryCache = object : LruCache<String, Bitmap>(cacheSize) {
override fun sizeOf(key: String, bitmap: Bitmap): Int {
// The cache size will be measured in kilobytes rather than
// number of items.
return bitmap.byteCount / 1024
}
}
...
}
Java
private LruCache<String, Bitmap> memoryCache;
@Override
protected void onCreate(Bundle savedInstanceState) {
...
// Get max available VM memory, exceeding this amount will throw an
// OutOfMemory exception. Stored in kilobytes as LruCache takes an
// int in its constructor.
final int maxMemory = (int) (Runtime.getRuntime().maxMemory() / 1024);
// Use 1/8th of the available memory for this memory cache.
final int cacheSize = maxMemory / 8;
memoryCache = new LruCache<String, Bitmap>(cacheSize) {
@Override
protected int sizeOf(String key, Bitmap bitmap) {
// The cache size will be measured in kilobytes rather than
// number of items.
return bitmap.getByteCount() / 1024;
}
};
...
}
public void addBitmapToMemoryCache(String key, Bitmap bitmap) {
if (getBitmapFromMemCache(key) == null) {
memoryCache.put(key, bitmap);
}
}
public Bitmap getBitmapFromMemCache(String key) {
return memoryCache.get(key);
}
private const val DISK_CACHE_SIZE = 1024 * 1024 * 10 // 10MB
private const val DISK_CACHE_SUBDIR = "thumbnails"
...
private var diskLruCache: DiskLruCache? = null
private val diskCacheLock = ReentrantLock()
private val diskCacheLockCondition: Condition = diskCacheLock.newCondition()
private var diskCacheStarting = true
override fun onCreate(savedInstanceState: Bundle?) {
...
// Initialize memory cache
...
// Initialize disk cache on background thread
val cacheDir = getDiskCacheDir(this, DISK_CACHE_SUBDIR)
InitDiskCacheTask().execute(cacheDir)
...
}
internal inner class InitDiskCacheTask : AsyncTask<File, Void, Void>() {
override fun doInBackground(vararg params: File): Void? {
diskCacheLock.withLock {
val cacheDir = params[0]
diskLruCache = DiskLruCache.open(cacheDir, DISK_CACHE_SIZE)
diskCacheStarting = false // Finished initialization
diskCacheLockCondition.signalAll() // Wake any waiting threads
}
return null
}
}
internal inner class BitmapWorkerTask : AsyncTask<Int, Unit, Bitmap>() {
...
// Decode image in background.
override fun doInBackground(vararg params: Int?): Bitmap? {
val imageKey = params[0].toString()
// Check disk cache in background thread
return getBitmapFromDiskCache(imageKey) ?:
// Not found in disk cache
decodeSampledBitmapFromResource(resources, params[0], 100, 100)
?.also {
// Add final bitmap to caches
addBitmapToCache(imageKey, it)
}
}
}
fun addBitmapToCache(key: String, bitmap: Bitmap) {
// Add to memory cache as before
if (getBitmapFromMemCache(key) == null) {
memoryCache.put(key, bitmap)
}
// Also add to disk cache
synchronized(diskCacheLock) {
diskLruCache?.apply {
if (!containsKey(key)) {
put(key, bitmap)
}
}
}
}
fun getBitmapFromDiskCache(key: String): Bitmap? =
diskCacheLock.withLock {
// Wait while disk cache is started from background thread
while (diskCacheStarting) {
try {
diskCacheLockCondition.await()
} catch (e: InterruptedException) {
}
}
return diskLruCache?.get(key)
}
// Creates a unique subdirectory of the designated app cache directory. Tries to use external
// but if not mounted, falls back on internal storage.
fun getDiskCacheDir(context: Context, uniqueName: String): File {
// Check if media is mounted or storage is built-in, if so, try and use external cache dir
// otherwise use internal cache dir
val cachePath =
if (Environment.MEDIA_MOUNTED == Environment.getExternalStorageState()
|| !isExternalStorageRemovable()) {
context.externalCacheDir.path
} else {
context.cacheDir.path
}
return File(cachePath + File.separator + uniqueName)
}
Java
private DiskLruCache diskLruCache;
private final Object diskCacheLock = new Object();
private boolean diskCacheStarting = true;
private static final int DISK_CACHE_SIZE = 1024 * 1024 * 10; // 10MB
private static final String DISK_CACHE_SUBDIR = "thumbnails";
@Override
protected void onCreate(Bundle savedInstanceState) {
...
// Initialize memory cache
...
// Initialize disk cache on background thread
File cacheDir = getDiskCacheDir(this, DISK_CACHE_SUBDIR);
new InitDiskCacheTask().execute(cacheDir);
...
}
class InitDiskCacheTask extends AsyncTask<File, Void, Void> {
@Override
protected Void doInBackground(File... params) {
synchronized (diskCacheLock) {
File cacheDir = params[0];
diskLruCache = DiskLruCache.open(cacheDir, DISK_CACHE_SIZE);
diskCacheStarting = false; // Finished initialization
diskCacheLock.notifyAll(); // Wake any waiting threads
}
return null;
}
}
class BitmapWorkerTask extends AsyncTask<Integer, Void, Bitmap> {
...
// Decode image in background.
@Override
protected Bitmap doInBackground(Integer... params) {
final String imageKey = String.valueOf(params[0]);
// Check disk cache in background thread
Bitmap bitmap = getBitmapFromDiskCache(imageKey);
if (bitmap == null) { // Not found in disk cache
// Process as normal
final Bitmap bitmap = decodeSampledBitmapFromResource(
getResources(), params[0], 100, 100));
}
// Add final bitmap to caches
addBitmapToCache(imageKey, bitmap);
return bitmap;
}
...
}
public void addBitmapToCache(String key, Bitmap bitmap) {
// Add to memory cache as before
if (getBitmapFromMemCache(key) == null) {
memoryCache.put(key, bitmap);
}
// Also add to disk cache
synchronized (diskCacheLock) {
if (diskLruCache != null && diskLruCache.get(key) == null) {
diskLruCache.put(key, bitmap);
}
}
}
public Bitmap getBitmapFromDiskCache(String key) {
synchronized (diskCacheLock) {
// Wait while disk cache is started from background thread
while (diskCacheStarting) {
try {
diskCacheLock.wait();
} catch (InterruptedException e) {}
}
if (diskLruCache != null) {
return diskLruCache.get(key);
}
}
return null;
}
// Creates a unique subdirectory of the designated app cache directory. Tries to use external
// but if not mounted, falls back on internal storage.
public static 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()) ||
!isExternalStorageRemovable() ? getExternalCacheDir(context).getPath() :
context.getCacheDir().getPath();
return new File(cachePath + File.separator + uniqueName);
}
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