1 public voiddisplayImage(String uri, ImageAware imageAware, DisplayImageOptions options,2 ImageSize targetSize, ImageLoadingListener listener, ImageLoadingProgressListener progressListener) {3 //检测参数有效性

4 checkConfiguration();5 if (imageAware == null) {6 throw newIllegalArgumentException(ERROR_WRONG_ARGUMENTS);7 }8 if (listener == null) {9 listener =defaultListener;10 }11 if (options == null) {12 options =configuration.defaultDisplayImageOptions;13 }14

15 if(TextUtils.isEmpty(uri)) {16 engine.cancelDisplayTaskFor(imageAware);17 listener.onLoadingStarted(uri, imageAware.getWrappedView());18 if(options.shouldShowImageForEmptyUri()) {19 imageAware.setImageDrawable(options.getImageForEmptyUri(configuration.resources));20 } else{21 imageAware.setImageDrawable(null);22 }23 listener.onLoadingComplete(uri, imageAware.getWrappedView(), null);24 return;25 }26

27 if (targetSize == null) {28 targetSize =ImageSizeUtils.defineTargetSizeForView(imageAware, configuration.getMaxImageSize());29 }30 String memoryCacheKey =MemoryCacheUtils.generateKey(uri, targetSize);31 engine.prepareDisplayTaskFor(imageAware, memoryCacheKey);32

33 listener.onLoadingStarted(uri, imageAware.getWrappedView());34

35 //尝试从内存中获取缓存，使用了MemoryCache组件

36 Bitmap bmp =configuration.memoryCache.get(memoryCacheKey);37 if (bmp != null && !bmp.isRecycled()) {38 //若已在内存缓存

39 L.d(LOG_LOAD_IMAGE_FROM_MEMORY_CACHE, memoryCacheKey);40 //如果需要处理，则调用ProcessAndDisplayImageTask.run()Bitmap进行处理

41 if(options.shouldPostProcess()) {42 ImageLoadingInfo imageLoadingInfo = newImageLoadingInfo(uri, imageAware, targetSize, memoryCacheKey,43 options, listener, progressListener, engine.getLockForUri(uri));44 ProcessAndDisplayImageTask displayTask = newProcessAndDisplayImageTask(engine, bmp, imageLoadingInfo,45 defineHandler(options));46 if(options.isSyncLoading()) {47 //处理Bitmap

48 displayTask.run();49 } else{50 engine.submit(displayTask);51 }52 } else{53 //无需处理Bitmap，则调用BitmapDisplayer组件将bitmap显示在imageAware上

54 options.getDisplayer().display(bmp, imageAware, LoadedFrom.MEMORY_CACHE);55 //回调加载完成

56 listener.onLoadingComplete(uri, imageAware.getWrappedView(), bmp);57 }58 } else{59 //若内存中无该缓存

60 if(options.shouldShowImageOnLoading()) {61 imageAware.setImageDrawable(options.getImageOnLoading(configuration.resources));62 } else if(options.isResetViewBeforeLoading()) {63 imageAware.setImageDrawable(null);64 }65 //封装加载信息

66 ImageLoadingInfo imageLoadingInfo = newImageLoadingInfo(uri, imageAware, targetSize, memoryCacheKey,67 options, listener, progressListener, engine.getLockForUri(uri));68 //创建LoadAndDisplayImageTask组件

69 LoadAndDisplayImageTask displayTask = newLoadAndDisplayImageTask(engine, imageLoadingInfo,70 defineHandler(options));71 if(options.isSyncLoading()) {72 //从磁盘或网络加载，下面会分析

73 displayTask.run();74 } else{75 engine.submit(displayTask);76 }77 }78 }79

80

81

82 @Override83 public voidrun() {84 if (waitIfPaused()) return;85 if (delayIfNeed()) return;86

87 ReentrantLock loadFromUriLock =imageLoadingInfo.loadFromUriLock;88 L.d(LOG_START_DISPLAY_IMAGE_TASK, memoryCacheKey);89 if(loadFromUriLock.isLocked()) {90 L.d(LOG_WAITING_FOR_IMAGE_LOADED, memoryCacheKey);91 }92

93 loadFromUriLock.lock();94 Bitmap bmp;95 try{96 checkTaskNotActual();97 //尝试从内存获取

98 bmp =configuration.memoryCache.get(memoryCacheKey);99 if (bmp == null ||bmp.isRecycled()) {100 //未在内存缓存，下面将分析tryLoadBitmap

101 bmp =tryLoadBitmap();102 if (bmp == null) return; //listener callback already was fired

103

104 checkTaskNotActual();105 checkTaskInterrupted();106

107 if(options.shouldPreProcess()) {108 L.d(LOG_PREPROCESS_IMAGE, memoryCacheKey);109 bmp =options.getPreProcessor().process(bmp);110 if (bmp == null) {111 L.e(ERROR_PRE_PROCESSOR_NULL, memoryCacheKey);112 }113 }114

115 if (bmp != null &&options.isCacheInMemory()) {116 L.d(LOG_CACHE_IMAGE_IN_MEMORY, memoryCacheKey);117 configuration.memoryCache.put(memoryCacheKey, bmp);118 }119 } else{120 loadedFrom =LoadedFrom.MEMORY_CACHE;121 L.d(LOG_GET_IMAGE_FROM_MEMORY_CACHE_AFTER_WAITING, memoryCacheKey);122 }123

124 if (bmp != null &&options.shouldPostProcess()) {125 L.d(LOG_POSTPROCESS_IMAGE, memoryCacheKey);126 bmp =options.getPostProcessor().process(bmp);127 if (bmp == null) {128 L.e(ERROR_POST_PROCESSOR_NULL, memoryCacheKey);129 }130 }131 checkTaskNotActual();132 checkTaskInterrupted();133 } catch(TaskCancelledException e) {134 fireCancelEvent();135 return;136 } finally{137 loadFromUriLock.unlock();138 }139

140 DisplayBitmapTask displayBitmapTask = newDisplayBitmapTask(bmp, imageLoadingInfo, engine, loadedFrom);141 runTask(displayBitmapTask, syncLoading, handler, engine);142 }143

144

145 private Bitmap tryLoadBitmap() throwsTaskCancelledException {146 Bitmap bitmap = null;147 try{148 //调用DiskCache组件尝试从磁盘获取缓存

149 File imageFile =configuration.diskCache.get(uri);150 if (imageFile != null && imageFile.exists() && imageFile.length() > 0) {151 //若已在磁盘缓存

152 L.d(LOG_LOAD_IMAGE_FROM_DISK_CACHE, memoryCacheKey);153 loadedFrom =LoadedFrom.DISC_CACHE;154

155 checkTaskNotActual();156 //将磁盘文件转换为bitmap对象

157 bitmap =decodeImage(Scheme.FILE.wrap(imageFile.getAbsolutePath()));158 }159 if (bitmap == null || bitmap.getWidth() <= 0 || bitmap.getHeight() <= 0) {160 //若不在磁盘缓存

161 L.d(LOG_LOAD_IMAGE_FROM_NETWORK, memoryCacheKey);162 loadedFrom =LoadedFrom.NETWORK;163

164 String imageUriForDecoding =uri;165 //从网络加载，并放入磁盘缓存，下面分析

166 if (options.isCacheOnDisk() &&tryCacheImageOnDisk()) {167 imageFile =configuration.diskCache.get(uri);168 if (imageFile != null) {169 imageUriForDecoding =Scheme.FILE.wrap(imageFile.getAbsolutePath());170 }171 }172

173 checkTaskNotActual();174 bitmap =decodeImage(imageUriForDecoding);175

176 if (bitmap == null || bitmap.getWidth() <= 0 || bitmap.getHeight() <= 0) {177 fireFailEvent(FailType.DECODING_ERROR, null);178 }179 }180 } catch(IllegalStateException e) {181 fireFailEvent(FailType.NETWORK_DENIED, null);182 } catch(TaskCancelledException e) {183 throwe;184 } catch(IOException e) {185 L.e(e);186 fireFailEvent(FailType.IO_ERROR, e);187 } catch(OutOfMemoryError e) {188 L.e(e);189 fireFailEvent(FailType.OUT_OF_MEMORY, e);190 } catch(Throwable e) {191 L.e(e);192 fireFailEvent(FailType.UNKNOWN, e);193 }194 returnbitmap;195 }196

197

198 private boolean tryCacheImageOnDisk() throwsTaskCancelledException {199 L.d(LOG_CACHE_IMAGE_ON_DISK, memoryCacheKey);200

201 booleanloaded;202 try{203 //下载图片，下面分析

204 loaded =downloadImage();205 if(loaded) {206 int width =configuration.maxImageWidthForDiskCache;207 int height =configuration.maxImageHeightForDiskCache;208 if (width > 0 || height > 0) {209 L.d(LOG_RESIZE_CACHED_IMAGE_FILE, memoryCacheKey);210 resizeAndSaveImage(width, height); //TODO : process boolean result

211 }212 }213 } catch(IOException e) {214 L.e(e);215 loaded = false;216 }217 returnloaded;218 }219

220 private boolean downloadImage() throwsIOException {221 //获取输入流

222 InputStream is =getDownloader().getStream(uri, options.getExtraForDownloader());223 if (is == null) {224 L.e(ERROR_NO_IMAGE_STREAM, memoryCacheKey);225 return false;226 } else{227 try{228 //保存到磁盘缓存

229 return configuration.diskCache.save(uri, is, this);230 } finally{231 IoUtils.closeSilently(is);232 }233 }234 }