Issue nostra13#170 - NPE after unmount SD card

Cache images on device's file system if SD card becomes unmounted

Author: nostra13

library/src/com/nostra13/universalimageloader/core/DefaultConfigurationFactory.java

@@ -44,12 +44,12 @@
  */
 public class DefaultConfigurationFactory {
 
-	/** Create {@linkplain HashCodeFileNameGenerator default implementation} of FileNameGenerator */
+	/** Creates {@linkplain HashCodeFileNameGenerator default implementation} of FileNameGenerator */
 	public static FileNameGenerator createFileNameGenerator() {
 		return new HashCodeFileNameGenerator();
 	}
 
-	/** Create default implementation of {@link DisckCacheAware} depends on incoming parameters */
+	/** Creates default implementation of {@link DisckCacheAware} depends on incoming parameters */
 	public static DiscCacheAware createDiscCache(Context context, FileNameGenerator discCacheFileNameGenerator, int discCacheSize, int discCacheFileCount) {
 		if (discCacheSize > 0) {
 			File individualCacheDir = StorageUtils.getIndividualCacheDirectory(context);
@@ -63,7 +63,17 @@ public static DiscCacheAware createDiscCache(Context context, FileNameGenerator
 		}
 	}
 
-	/** Create default implementation of {@link MemoryCacheAware} depends on incoming parameters */
+	/** Creates reserve disc cache which will be used if primary disc cache becomes unavailable */
+	public static DiscCacheAware createReserveDiscCache(Context context) {
+		File cacheDir = context.getCacheDir();
+		File individualDir = new File(cacheDir, "uil-images");
+		if (individualDir.exists() || individualDir.mkdir()) {
+			cacheDir = individualDir;
+		}
+		return new TotalSizeLimitedDiscCache(cacheDir, 2 * 1024 * 1024); // limit - 2 Mb
+	}
+
+	/** Creates default implementation of {@link MemoryCacheAware} depends on incoming parameters */
 	public static MemoryCacheAware<String, Bitmap> createMemoryCache(int memoryCacheSize, boolean denyCacheImageMultipleSizesInMemory) {
 		MemoryCacheAware<String, Bitmap> memoryCache = new UsingFreqLimitedMemoryCache(memoryCacheSize);
 		if (denyCacheImageMultipleSizesInMemory) {
@@ -72,12 +82,12 @@ public static MemoryCacheAware<String, Bitmap> createMemoryCache(int memoryCache
 		return memoryCache;
 	}
 
-	/** Create default implementation of {@link ImageDownloader} - {@link BaseImageDownloader} */
+	/** Creates default implementation of {@link ImageDownloader} - {@link BaseImageDownloader} */
 	public static ImageDownloader createImageDownloader(Context context) {
 		return new BaseImageDownloader(context);
 	}
 
-	/** Create default implementation of {@link BitmapDisplayer} */
+	/** Creates default implementation of {@link BitmapDisplayer} */
 	public static BitmapDisplayer createBitmapDisplayer() {
 		return new SimpleBitmapDisplayer();
 	}

library/src/com/nostra13/universalimageloader/core/ImageLoaderConfiguration.java

@@ -67,6 +67,7 @@ public final class ImageLoaderConfiguration {
 	final ThreadFactory displayImageThreadFactory;
 	final boolean loggingEnabled;
 
+	final DiscCacheAware reserveDiscCache;
 	final ImageDownloader networkDeniedDownloader;
 	final ImageDownloader slowNetworkDownloader;
 
@@ -97,6 +98,8 @@ public Thread newThread(Runnable r) {
 
 		networkDeniedDownloader = new NetworkDeniedImageDownloader(downloader);
 		slowNetworkDownloader = new SlowNetworkImageDownloader(downloader);
+
+		reserveDiscCache = DefaultConfigurationFactory.createReserveDiscCache(context);
 	}
 
 	/**

library/src/com/nostra13/universalimageloader/core/LoadAndDisplayImageTask.java

@@ -216,6 +216,10 @@ private boolean checkTaskIsInterrupted() {
 	private Bitmap tryLoadBitmap() {
 		DiscCacheAware discCache = configuration.discCache;
 		File imageFile = discCache.get(uri);
+		File cacheDir = imageFile.getParentFile();
+		if (cacheDir == null || (!cacheDir.exists() && !cacheDir.mkdirs())) {
+			imageFile = configuration.reserveDiscCache.get(uri);
+		}
 
 		Bitmap bitmap = null;
 		try {
@@ -314,11 +318,6 @@ private Bitmap decodeWithOOMHandling(URI imageUri) throws IOException {
 	}
 
 	private void saveImageOnDisc(File targetFile) throws IOException, URISyntaxException {
-		File cacheDir = targetFile.getParentFile();
-		if (cacheDir == null || !cacheDir.exists()) {
-			cacheDir.mkdirs();
-		}
-
 		int width = configuration.maxImageWidthForDiscCache;
 		int height = configuration.maxImageHeightForDiscCache;
 		if (width > 0 || height > 0) {