Glide的简单梳理
Posted 清浅岁月
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#Glide
Glide的使用
implementation 'com.github.bumptech.glide:glide:4.8.0'
annotationProcessor 'com.github.bumptech.glide:compiler:4.8.0'
简单的使用
RequestOptions options =new RequestOptions().centerCrop();
Glide.with(this).load("").apply(options).into(imageview)
Glide 图片加载流程
Glide的intoc传的参数有Target和ImagView，其实图片ImagView最后也会变成一个Target,通过glideContext.buildImageViewTarget
public ViewTarget<ImageView, TranscodeType> into(@NonNull ImageView view)
Util.assertMainThread();
Preconditions.checkNotNull(view);
RequestOptions requestOptions = this.requestOptions;
if (!requestOptions.isTransformationSet()
&& requestOptions.isTransformationAllowed()
&& view.getScaleType() != null)
// Clone in this method so that if we use this RequestBuilder to load into a View and then
// into a different target, we don't retain the transformation applied based on the previous
// View's scale type.
switch (view.getScaleType())
case CENTER_CROP:
requestOptions = requestOptions.clone().optionalCenterCrop();
break;
case CENTER_INSIDE:
requestOptions = requestOptions.clone().optionalCenterInside();
break;
case FIT_CENTER:
case FIT_START:
case FIT_END:
requestOptions = requestOptions.clone().optionalFitCenter();
break;
case FIT_XY:
requestOptions = requestOptions.clone().optionalCenterInside();
break;
case CENTER:
case MATRIX:
default:
// Do nothing.
return into(
glideContext.buildImageViewTarget(view, transcodeClass),
/*targetListener=*/ null,
requestOptions);
这个是传递CustomViewTarget的参数的方法：
最终都是Target的形式处理的。
private <Y extends Target<TranscodeType>> Y into(
@NonNull Y target,
@Nullable RequestListener<TranscodeType> targetListener,
@NonNull RequestOptions options)
Util.assertMainThread();
Preconditions.checkNotNull(target);
if (!isModelSet)
throw new IllegalArgumentException("You must call #load() before calling #into()");
options = options.autoClone();
Request request = buildRequest(target, targetListener, options);
Request previous = target.getRequest();
if (request.isEquivalentTo(previous)
&& !isSkipMemoryCacheWithCompletePreviousRequest(options, previous))
request.recycle();
// If the request is completed, beginning again will ensure the result is re-delivered,
// triggering RequestListeners and Targets. If the request is failed, beginning again will
// restart the request, giving it another chance to complete. If the request is already
// running, we can let it continue running without interruption.
if (!Preconditions.checkNotNull(previous).isRunning())
// Use the previous request rather than the new one to allow for optimizations like skipping
// setting placeholders, tracking and un-tracking Targets, and obtaining View dimensions
// that are done in the individual Request.
previous.begin();
return target;
requestManager.clear(target);
target.setRequest(request);
requestManager.track(target, request);
return target;
之后将Target转换成Request再处理,再Glide的build的时候指定默认的Request为singleRequest，Target转换成一个singleRequest去处理的。最终调用Request的begin开始处理图片。
singleRequest
public void begin()
assertNotCallingCallbacks();
stateVerifier.throwIfRecycled();
startTime = LogTime.getLogTime();
if (model == null)
if (Util.isValidDimensions(overrideWidth, overrideHeight))
width = overrideWidth;
height = overrideHeight;
// Only log at more verbose log levels if the user has set a fallback drawable, because
// fallback Drawables indicate the user expects null models occasionally.
int logLevel = getFallbackDrawable() == null ? Log.WARN : Log.DEBUG;
onLoadFailed(new GlideException("Received null model"), logLevel);
return;
if (status == Status.RUNNING)
throw new IllegalArgumentException("Cannot restart a running request");
// If we're restarted after we're complete (usually via something like a notifyDataSetChanged
// that starts an identical request into the same Target or View), we can simply use the
// resource and size we retrieved the last time around and skip obtaining a new size, starting a
// new load etc. This does mean that users who want to restart a load because they expect that
// the view size has changed will need to explicitly clear the View or Target before starting
// the new load.
if (status == Status.COMPLETE)
onResourceReady(resource, DataSource.MEMORY_CACHE);
return;
// Restarts for requests that are neither complete nor running can be treated as new requests
// and can run again from the beginning.
status = Status.WAITING_FOR_SIZE;
if (Util.isValidDimensions(overrideWidth, overrideHeight))
onSizeReady(overrideWidth, overrideHeight);
else
target.getSize(this);
if ((status == Status.RUNNING || status == Status.WAITING_FOR_SIZE)
&& canNotifyStatusChanged())
target.onLoadStarted(getPlaceholderDrawable());
if (IS_VERBOSE_LOGGABLE)
logV("finished run method in " + LogTime.getElapsedMillis(startTime));
onSizeReady(overrideWidth, overrideHeight);
看一下这个方法：
/**
* A callback method that should never be invoked directly.
*/
@Override
public void onSizeReady(int width, int height)
stateVerifier.throwIfRecycled();
if (IS_VERBOSE_LOGGABLE)
logV("Got onSizeReady in " + LogTime.getElapsedMillis(startTime));
if (status != Status.WAITING_FOR_SIZE)
return;
status = Status.RUNNING;
float sizeMultiplier = requestOptions.getSizeMultiplier();
this.width = maybeApplySizeMultiplier(width, sizeMultiplier);
this.height = maybeApplySizeMultiplier(height, sizeMultiplier);
if (IS_VERBOSE_LOGGABLE)
logV("finished setup for calling load in " + LogTime.getElapsedMillis(startTime));
loadStatus = engine.load(
glideContext,
model,
requestOptions.getSignature(),
this.width,
this.height,
requestOptions.getResourceClass(),
transcodeClass,
priority,
requestOptions.getDiskCacheStrategy(),
requestOptions.getTransformations(),
requestOptions.isTransformationRequired(),
requestOptions.isScaleOnlyOrNoTransform(),
requestOptions.getOptions(),
requestOptions.isMemoryCacheable(),
requestOptions.getUseUnlimitedSourceGeneratorsPool(),
requestOptions.getUseAnimationPool(),
requestOptions.getOnlyRetrieveFromCache(),
this);
// This is a hack that's only useful for testing right now where loads complete synchronously
// even though under any executor running on any thread but the main thread, the load would
// have completed asynchronously.
if (status != Status.RUNNING)
loadStatus = null;
if (IS_VERBOSE_LOGGABLE)
logV("finished onSizeReady in " + LogTime.getElapsedMillis(startTime));
真正开始的地方是这里：
engine.load里真正的开始加载的，调用的是Engine的load方法区获取的，Engine对象时在SingleRequest的obtain的时候 从glideContent中获取的，glideContent是从Glide初始化的时候new出来的，Engine也是。
看一下这里
*/
public <R> LoadStatus load(
GlideContext glideContext,
Object model,
Key signature,
int width,
int height,
Class<?> resourceClass,
Class<R> transcodeClass,
Priority priority,
DiskCacheStrategy diskCacheStrategy,
Map<Class<?>, Transformation<?>> transformations,
boolean isTransformationRequired,
boolean isScaleOnlyOrNoTransform,
Options options,
boolean isMemoryCacheable,
boolean useUnlimitedSourceExecutorPool,
boolean useAnimationPool,
boolean onlyRetrieveFromCache,
ResourceCallback cb)
Util.assertMainThread();
long startTime = VERBOSE_IS_LOGGABLE ? LogTime.getLogTime() : 0;
// 生成key
EngineKey key = keyFactory.buildKey(model, signature, width, height, transformations,
resourceClass, transcodeClass, options);
// 从获取资源中获取，就是正在展示中的图片中加载
EngineResource<?> active = loadFromActiveResources(key, isMemoryCacheable);
if (active != null)
cb.onResourceReady(active, DataSource.MEMORY_CACHE);
if (VERBOSE_IS_LOGGABLE)
logWithTimeAndKey("Loaded resource from active resources", startTime, key);
return null;
// 从缓存资源中获取
EngineResource<?> cached = loadFromCache(key, isMemoryCacheable);
if (cached != null)
cb.onResourceReady(cached, DataSource.MEMORY_CACHE);
if (VERBOSE_IS_LOGGABLE)
logWithTimeAndKey("Loaded resource from cache", startTime, key);
return null;
// 走到这里如果还没有获取到资源就需要网络加载获取
EngineJob<?> current = jobs.get(key, onlyRetrieveFromCache);
if (current != null)
current.addCallback(cb);
if (VERBOSE_IS_LOGGABLE)
logWithTimeAndKey("Added to existing load", startTime, key);
return new LoadStatus(cb, current);
EngineJob<R> engineJob =
engineJobFactory.build(
key,
isMemoryCacheable,
useUnlimitedSourceExecutorPool,
useAnimationPool,
onlyRetrieveFromCache);
DecodeJob<R> decodeJob =
decodeJobFactory.build(
glideContext,
model,
key,
signature,
width,
height,
resourceClass,
transcodeClass,
priority,
diskCacheStrategy,
transformations,
isTransformationRequired,
isScaleOnlyOrNoTransform,
onlyRetrieveFromCache,
options,
engineJob);
jobs.put(key, engineJob);
engineJob.addCallback(cb);
engineJob.start(decodeJob);
if (VERBOSE_IS_LOGGABLE)
logWithTimeAndKey("Started new load", startTime, key);
return new LoadStatus(cb, engineJob);
稍微总结一下：
- loadFromActiveResources
- loadFromCache
- 从硬盘获取
- 从网络获取
1. loadFromActiveResources
下面看下一loadFromActiveResources是从ActiveResources中获取的：
@Nullable
EngineResource<?> get(Key key)
ResourceWeakReference activeRef = activeEngineResources.get(key);
if (activeRef == null)
return null;
EngineResource<?> active = activeRef.get();
if (active == null)
cleanupActiveReference(activeRef);
return active;
@VisibleForTesting
final Map<Key, ResourceWeakReference> activeEngineResources = new HashMap<>();
activeEngineResources是一个hashmap，ResourceWeakReference弱引用处理的。
@VisibleForTesting
static final class ResourceWeakReference extends WeakReference<EngineResource<?>>
@SuppressWarnings("WeakerAccess") @Synthetic final Key key;
@SuppressWarnings("WeakerAccess") @Synthetic final boolean isCacheable;
@Nullable @SuppressWarnings("WeakerAccess") @Synthetic Resource<?> resource;
@Synthetic
@SuppressWarnings("WeakerAccess")
ResourceWeakReference(
@NonNull Key key,
@NonNull EngineResource<?> referent,
@NonNull ReferenceQueue<? super EngineResource<?>> queue,
boolean isActiveResourceRetentionAllowed)
super(referent, queue);
this.key = Preconditions.checkNotNull(key);
this.resource =
referent.isCacheable() && isActiveResourceRetentionAllowed
? Preconditions.checkNotNull(referent.getResource()) : null;
isCacheable = referent.isCacheable();
void reset()
resource = null;
clear();
2. loadFromCache
private EngineResource<?> loadFromCache(Key key, boolean isMemoryCacheable)
if (!isMemoryCacheable)
return null;
EngineResource<?> cached = getEngineResourceFromCache(key);
if (cached != null)
cached.acquire();
activeResources.activate(key, cached);
return cached;
看一下：
getEngineResourceFromCache
private EngineResource<?> getEngineResourceFromCache(Key key)
Resource<?> cached = cache.remove(key);
final EngineResource<?> result;
if (cached == null)
result = null;
else if (cached instanceof EngineResource)
// Save an object allocation if we've cached an EngineResource (the typical case).
result = (EngineResource<?>) cached;
else
result = new EngineResource<>(cached, true /*isMemoryCacheable*/, true /*isRecyclable*/);
return result;
将资源添加到ActiveResources中方便下次再次获取。getEngineResourceFromCache是从这里MemoryCache中获取的，MemoryCache是接口，坑定是从初始化设置的子类获取的。看一下Glide的初始化
@NonNull
Glide build(@NonNull Context context)
if (sourceExecutor == null)
sourceExecutor = GlideExecutor.newSourceExecutor();
if (diskCacheExecutor == null)
diskCacheExecutor = GlideExecutor.newDiskCacheExecutor();
if (animationExecutor == null)
animationExecutor = GlideExecutor.newAnimationExecutor();
if (memorySizeCalculator == null)
memorySizeCalculator = new MemorySizeCalculator.Builder(context).build();
if (connectivityMonitorFactory == null)
connectivityMonitorFactory = new DefaultConnectivityMonitorFactory();
if (bitmapPool == null)
int size = memorySizeCalculator.getBitmapPoolSize();
if (size > 0)
bitmapPool = new LruBitmapPool(size);
else
bitmapPool = new BitmapPoolAdapter();
if (arrayPool == null)
arrayPool = new LruArrayPool(memorySizeCalculator.getArrayPoolSizeInBytes());
// 这个就是
if (memoryCache == null)
memoryCache = new LruResourceCache(memorySizeCalculator.getMemoryCacheSize());
if (diskCacheFactory == null)
diskCacheFactory = new InternalCacheDiskCacheFactory(context);
if (engine == null)
engine =
new Engine(
memoryCache,
diskCacheFactory,
diskCacheExecutor,
sourceExecutor,
GlideExecutor.newUnlimitedSourceExecutor(),
GlideExecutor.newAnimationExecutor(),
isActiveResourceRetentionAllowed);
RequestManagerRetriever requestManagerRetriever =
new RequestManagerRetriever(requestManagerFactory);
return new Glide(
context,
engine,
memoryCache,
bitmapPool,
arrayPool,
requestManagerRetriever,
connectivityMonitorFactory,
logLevel,
defaultRequestOptions.lock(),
defaultTransitionOptions);
在这里配置的内存缓存对象
if (memoryCache == null)
memoryCache = new LruResourceCache(memorySizeCalculator.getMemoryCacheSize());
LruResourceCache是继承LruCache，实现MemoryCache接口的。
看一下LruResourceCache 的remove方法，LruResourceCache中没有重写MemoryCache的remove的方法，直接是LruCache的remove方法，疑惑，为啥不直接用get要用remove的方法？
3. 从硬盘获取
在Engine的load中后面创建了，EngineJob，和decodeJob，EngineJob辅助Engine处理任务，
DecodeJob是一个实现了Runnable，最后调用的是EngineJob的start，嗲用线程池进行任务处理。
public void start(DecodeJob<R> decodeJob)
this.decodeJob = decodeJob;
GlideExecutor executor = decodeJob.willDecodeFromCache()
? diskCacheExecutor
: getActiveSourceExecutor();
executor.execute(decodeJob);
再看一下DecodeJob的的Run方法怎么处理的，
@Override
public void run()
// This should be much more fine grained, but since Java's thread pool implementation silently
// swallows all otherwise fatal exceptions, this will at least make it obvious to developers
// that something is failing.
GlideTrace.beginSectionFormat("DecodeJob#run(model=%s)", model);
// Methods in the try statement can invalidate currentFetcher, so set a local variable here to
// ensure that the fetcher is cleaned up either way.
DataFetcher<?> localFetcher = currentFetcher;
try
if (isCancelled)
notifyFailed();
return;
// 这里开始执行
runWrapped();
catch (Throwable t)
// Catch Throwable and not Exception to handle OOMs. Throwables are swallowed by our
// usage of .submit() in GlideExecutor so we're not silently hiding crashes by doing this. We
// are however ensuring that our callbacks are always notified when a load fails. Without this
// notification, uncaught throwables never notify the corresponding callbacks, which can cause
// loads to silently hang forever, a case that's especially bad for users using Futures on
// background threads.
if (Log.isLoggable(TAG, Log.DEBUG))
Log.d(TAG, "DecodeJob threw unexpectedly"
+ ", isCancelled: " + isCancelled
+ ", stage: " + stage, t);
// When we're encoding we've already notified our callback and it isn't safe to do so again.
if (stage != Stage.ENCODE)
throwables.add(t);
notifyFailed();
if (!isCancelled)
throw t;
finally
// Keeping track of the fetcher here and calling cleanup is excessively paranoid, we call
// close in all cases anyway.
if (localFetcher != null)
localFetcher.cleanup();
GlideTrace.endSection();
private void runWrapped()
switch (runReason)
case INITIALIZE:
stage = getNextStage(Stage.INITIALIZE);
currentGenerator = getNextGenerator();
runGenerators();
break;
case SWITCH_TO_SOURCE_SERVICE:
runGenerators();
break;
case DECODE_DATA:
decodeFromRetrievedData();
break;
default:
throw new IllegalStateException("Unrecognized run reason: " + runReason);
看一下：
getNextGenerator();
runGenerators();
private DataFetcherGenerator getNextGenerator()
switch (stage)
case RESOURCE_CACHE:
// 从磁盘缓存中获取包含被转换过的资源
return new ResourceCacheGenerator(decodeHelper, this);
case DATA_CACHE:
// 从磁盘缓存中获取原始图片，未作任何转换的图
return new DataCacheGenerator(decodeHelper, this);
case SOURCE:
// 从网络加载图片
return new SourceGenerator(decodeHelper, this);
case FINISHED:
return null;
default:
throw new IllegalStateException("Unrecognized stage: " + stage);
private void runGenerators()
currentThread = Thread.currentThread();
startFetchTime = LogTime.getLogTime();
boolean isStarted = false;
while (!isCancelled && currentGenerator != null
&& !(isStarted = currentGenerator.startNext()))
stage = getNextStage(stage);
currentGenerator = getNextGenerator();
if (stage == Stage.SOURCE)
reschedule();
return;
// We've run out of stages and generators, give up.
if ((stage == Stage.FINISHED || isCancelled) && !isStarted)
notifyFailed();
// Otherwise a generator started a new load and we expect to be called back in
// onDataFetcherReady.
网络请求在HttpGlideUrlLoader类中才开始，
@Override
public LoadData<InputStream> buildLoadData(@NonNull GlideUrl model, int width, int height,
@NonNull Options options)
// GlideUrls memoize parsed URLs so caching them saves a few object instantiations and time
// spent parsing urls.
GlideUrl url = model;
if (modelCache != null)
url = modelCache.get(model, 0, 0);
if (url == null)
modelCache.put(model, 0, 0, model);
url = model;
int timeout = options.get(TIMEOUT);
return new LoadData<>(url, new HttpUrlFetcher(url, timeout));
HttpUrlFetcher中通过HttpURLConnection进行网络处理的。
BitMapPool的使用
在into的流程中是没有会用到BitMapPool的，BitMapPool的使用主要是在transform中，图像的变化中，先从BitMapPool获取，没有在拿原始图片变换，变化完成之后再放到BitMapPool池中进行缓存。
public abstract class BitmapTransformation implements Transformation<Bitmap>
@NonNull
@Override
public final Resource<Bitmap> transform(
@NonNull Context context, @NonNull Resource<Bitmap> resource, int outWidth, int outHeight)
if (!Util.isValidDimensions(outWidth, outHeight))
throw new IllegalArgumentException(
"Cannot apply transformation on width: " + outWidth + " or height: " + outHeight
+ " less than or equal to zero and not Target.SIZE_ORIGINAL");
BitmapPool bitmapPool = Glide.get(context).getBitmapPool();
Bitmap toTransform = resource.get();
int targetWidth = outWidth == Target.SIZE_ORIGINAL ? toTransform.getWidth() : outWidth;
int targetHeight = outHeight == Target.SIZE_ORIGINAL ? toTransform.getHeight() : outHeight;
Bitmap transformed = transform(bitmapPool, toTransform, targetWidth, targetHeight);
final Resource<Bitmap> result;
if (toTransform.equals(transformed))
result = resource;
else
result = BitmapResource.obtain(transformed, bitmapPool);
return result;
protected abstract Bitmap transform(
@NonNull BitmapPool pool, @NonNull Bitmap toTransform, int outWidth, int outHeight);
BitmapTransformation实现Transformation接口，而且是一个抽象类,其子类有CircleCrop，CenterCrop，FitCenter，RoundedCorners等圆形变化，圆角变化这些都是他的子类，自定义类型可以直接继承BitmapTransformation去处理。
看一下BitmapPool中是如何获取bitmap的，根据控件大缓存图片，BitmapPool是如何存放图片的：
@Override
public synchronized void put(Bitmap bitmap)
if (bitmap == null)
throw new NullPointerException("Bitmap must not be null");
if (bitmap.isRecycled())
throw new IllegalStateException("Cannot pool recycled bitmap");
if (!bitmap.isMutable() || strategy.getSize(bitmap) > maxSize
|| !allowedConfigs.contains(bitmap.getConfig()))
if (Log.isLoggable(TAG, Log.VERBOSE))
Log.v(TAG, "Reject bitmap from pool"
+ ", bitmap: " + strategy.logBitmap(bitmap)
+ ", is mutable: " + bitmap.isMutable()
+ ", is allowed config: " + allowedConfigs.contains(bitmap.getConfig()));
bitmap.recycle();
return;
final int size = strategy.getSize(bitmap);
strategy.put(bitmap);
tracker.add(bitmap);
puts++;
currentSize += size;
if (Log.isLoggable(TAG, Log.VERBOSE))
Log.v(TAG, "Put bitmap in pool=" + strategy.logBitmap(bitmap));
dump();
evict();
是通过LruPoolStrategy缓存池策略决定的，有三种策略：SizeConfigStrategy，AttributeStrategy，SizeStrategy三种策略，根据版本在Glide的build文件中根据版本做了设置，4.0以上使用的是SizeConfigStrategy大小配置策略，看一下大小配置策略中谁如何存取的：
SizeConfigStrategy中put和get方法：
@Override
public void put(Bitmap bitmap)
int size = Util.getBitmapByteSize(bitmap);
Key key = keyPool.get(size, bitmap.getConfig());
groupedMap.put(key, bitmap);
NavigableMap<Integer, Integer> sizes = getSizesForConfig(bitmap.getConfig());
Integer current = sizes.get(key.size);
sizes.put(key.size, current == null ? 1 : current + 1);
@Override
@Nullable
public Bitmap get(int width, int height, Bitmap.Config config)
int size = Util.getBitmapByteSize(width, height, config);
Key bestKey = findBestKey(size, config);
Bitmap result = groupedMap.get(bestKey);
if (result != null)
// Decrement must be called before reconfigure.
decrementBitmapOfSize(bestKey.size, result);
result.reconfigure(width, height,
result.getConfig() != null ? result.getConfig() : Bitmap.Config.ARGB_8888);
return result;
存取数据都是需要Key的，看一下去和获取到key：
private Key findBestKey(int size, Bitmap.Config config)
Key result = keyPool.get(size, config);
for (Bitmap.Config possibleConfig : getInConfigs(config))
NavigableMap<Integer, Integer> sizesForPossibleConfig = getSizesForConfig(possibleConfig);
Integer possibleSize = sizesForPossibleConfig.ceilingKey(size);
if (possibleSize != null && possibleSize <= size * MAX_SIZE_MULTIPLE)
if (possibleSize != size
|| (possibleConfig == null ? config != null : !possibleConfig.equals(config)))
keyPool.offer(result);
result = keyPool.get(possibleSize, possibleConfig);
break;
return result;
根据Bitmap.Config获取到一组数据，再通过
关键在这里：
NavigableMap<Integer, Integer> sizesForPossibleConfig = getSizesForConfig(possibleConfig);
Integer possibleSize = sizesForPossibleConfig.ceilingKey(size);
SortMap的ceilingKey返回大于等于键的最小值，如果当前获取5x5的一张图片，缓存池中有一张6x6,7x7的将优先返回6x6的图片资源，所以通过复用之前的图片资源。
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