if (bitmap == null || bitmap.getWidth() <= 0 || bitmap.getHeight() <= 0) {
L.d(LOG_LOAD_IMAGE_FROM_NETWORK, memoryCacheKey);
loadedFrom = LoadedFrom.NETWORK;
String imageUriForDecoding = uri;
if (options.isCacheOnDisk() && tryCacheImageOnDisk()) {
imageFile = configuration.diskCache.get(uri);
if (imageFile != null) {
imageUriForDecoding = Scheme.FILE.wrap(imageFile.getAbsolutePath());
}
}
checkTaskNotActual();
bitmap = decodeImage(imageUriForDecoding);
if (bitmap == null || bitmap.getWidth() <= 0 || bitmap.getHeight() <= 0) {
fireFailEvent(FailType.DECODING_ERROR, null);
}
}
第1行表示从文件缓存中获取的Bitmap为null，或者宽高为0,就去网络上面获取Bitmap，来到第6行代码是否配置了DisplayImageOptions的isCacheOnDisk，表示是否需要将Bitmap对象保存在文件系统中，一般我们需要配置为true, 默认是false这个要注意下，然后就是执行tryCacheImageOnDisk()方法，去服务器上面拉取图片并保存在本地文件中
private Bitmap decodeImage(String imageUri) throws IOException {
ViewScaleType viewScaleType = imageAware.getScaleType();
ImageDecodingInfo decodingInfo = new ImageDecodingInfo(memoryCacheKey, imageUri, uri, targetSize, viewScaleType,
getDownloader(), options);
return decoder.decode(decodingInfo);
}
/** @return <b>true</b> - if image was downloaded successfully; <b>false</b> - otherwise */
private boolean tryCacheImageOnDisk() throws TaskCancelledException {
L.d(LOG_CACHE_IMAGE_ON_DISK, memoryCacheKey);
boolean loaded;
try {
loaded = downloadImage();
if (loaded) {
int width = configuration.maxImageWidthForDiskCache;
int height = configuration.maxImageHeightForDiskCache;
if (width > 0 || height > 0) {
L.d(LOG_RESIZE_CACHED_IMAGE_FILE, memoryCacheKey);
resizeAndSaveImage(width, height); // TODO : process boolean result
}
}
} catch (IOException e) {
L.e(e);
loaded = false;
}
return loaded;
}
private boolean downloadImage() throws IOException {
InputStream is = getDownloader().getStream(uri, options.getExtraForDownloader());
return configuration.diskCache.save(uri, is, this);
}
