一、Glide基本用法
Glide
.with(this)
.load(path)
.into(ivBg);
二、Glide 源码讲解
Glide源码分为三部分，with() , load(), into(),本文现讲述with部分。
public static RequestManager with(@NonNull Activity activity) {
return getRetriever(activity).get(activity);
}
@NonNull
private static RequestManagerRetriever getRetriever(@Nullable Context context) {
return Glide.get(context).getRequestManagerRetriever();
}
@NonNull
public static Glide get(@NonNull Context context) {
if (glide == null) {
synchronized (Glide.class) {
if (glide == null) {
checkAndInitializeGlide(context);
}
}
}
return glide;
}
看下GlideBuilder中初始化的一些类
Glide build(@NonNull Context context) {
//创建执行器，用于从数据源获取数据，例如网络请求
if (sourceExecutor == null) {
sourceExecutor = GlideExecutor.newSourceExecutor();
}
//创建执行器，用于从本地缓存获取数据
if (diskCacheExecutor == null) {
diskCacheExecutor = GlideExecutor.newDiskCacheExecutor();
}
if (animationExecutor == null) {
animationExecutor = GlideExecutor.newAnimationExecutor();
}
//根据当前机器参数计算需要的缓存大小
if (memorySizeCalculator == null) {
memorySizeCalculator = new MemorySizeCalculator.Builder(context).build();
}
if (connectivityMonitorFactory == null) {
connectivityMonitorFactory = new DefaultConnectivityMonitorFactory();
}
//创建bitmap池，用于回收LruCache缓存的图片，把图片会受到BitmapPool中，这样下次再创建图片的时候，可以复用，避免连续创建回收内存，造成内存抖动
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());
}
//创建内存缓存
if (memoryCache == null) {
memoryCache = new LruResourceCache(memorySizeCalculator.getMemoryCacheSize());
}
//创建磁盘缓存
if (diskCacheFactory == null) {
diskCacheFactory = new InternalCacheDiskCacheFactory(context);
}
//创建engin用于真正的处理request请求，如发起网络图片，从磁盘读取图片等
if (engine == null) {
engine =
new Engine(
memoryCache,
diskCacheFactory,
diskCacheExecutor,
sourceExecutor,
GlideExecutor.newUnlimitedSourceExecutor(),
GlideExecutor.newAnimationExecutor(),
isActiveResourceRetentionAllowed);
}
if (defaultRequestListeners == null) {
defaultRequestListeners = Collections.emptyList();
} else {
defaultRequestListeners = Collections.unmodifiableList(defaultRequestListeners);
}
//创建RequestManagerRetriever
RequestManagerRetriever requestManagerRetriever =
new RequestManagerRetriever(requestManagerFactory);
return new Glide(
context,
engine,
memoryCache,
bitmapPool,
arrayPool,
requestManagerRetriever,
connectivityMonitorFactory,
logLevel,
defaultRequestOptions.lock(),
defaultTransitionOptions,
defaultRequestListeners,
isLoggingRequestOriginsEnabled);
}
Glide创建
Glide() {
this.engine = engine;
this.bitmapPool = bitmapPool;
this.arrayPool = arrayPool;
this.memoryCache = memoryCache;
this.requestManagerRetriever = requestManagerRetriever;
this.connectivityMonitorFactory = connectivityMonitorFactory;
DecodeFormat decodeFormat = defaultRequestOptions.getOptions().get(Downsampler.DECODE_FORMAT);
bitmapPreFiller = new BitmapPreFiller(memoryCache, bitmapPool, decodeFormat);
final Resources resources = context.getResources();
registry = new Registry();
registry.register(new DefaultImageHeaderParser());
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O_MR1) {
registry.register(new ExifInterfaceImageHeaderParser());
}
List imageHeaderParsers = registry.getImageHeaderParsers();
Downsampler downsampler =
new Downsampler(
imageHeaderParsers,
resources.getDisplayMetrics(),
bitmapPool,
arrayPool);
ByteBufferGifDecoder byteBufferGifDecoder =
new ByteBufferGifDecoder(context, imageHeaderParsers, bitmapPool, arrayPool);
ResourceDecoder parcelFileDescriptorVideoDecoder =
VideoDecoder.parcel(bitmapPool);
ByteBufferBitmapDecoder byteBufferBitmapDecoder = new ByteBufferBitmapDecoder(downsampler);
StreamBitmapDecoder streamBitmapDecoder = new StreamBitmapDecoder(downsampler, arrayPool);
ResourceDrawableDecoder resourceDrawableDecoder =
new ResourceDrawableDecoder(context);
ResourceLoader.StreamFactory resourceLoaderStreamFactory =
new ResourceLoader.StreamFactory(resources);
ResourceLoader.UriFactory resourceLoaderUriFactory =
new ResourceLoader.UriFactory(resources);
ResourceLoader.FileDescriptorFactory resourceLoaderFileDescriptorFactory =
new ResourceLoader.FileDescriptorFactory(resources);
ResourceLoader.AssetFileDescriptorFactory resourceLoaderAssetFileDescriptorFactory =
new ResourceLoader.AssetFileDescriptorFactory(resources);
BitmapEncoder bitmapEncoder = new BitmapEncoder(arrayPool);
BitmapBytesTranscoder bitmapBytesTranscoder = new BitmapBytesTranscoder();
GifDrawableBytesTranscoder gifDrawableBytesTranscoder = new GifDrawableBytesTranscoder();
ContentResolver contentResolver = context.getContentResolver();
registry
.append(ByteBuffer.class, new ByteBufferEncoder())
.append(InputStream.class, new StreamEncoder(arrayPool))
...
.register(
Drawable.class,
byte[].class,
new DrawableBytesTranscoder(
bitmapPool, bitmapBytesTranscoder, gifDrawableBytesTranscoder))
.register(GifDrawable.class, byte[].class, gifDrawableBytesTranscoder);
ImageViewTargetFactory imageViewTargetFactory = new ImageViewTargetFactory();
glideContext =
new GlideContext(
context,
arrayPool,
registry,
imageViewTargetFactory,
defaultRequestOptions,
defaultTransitionOptions,
defaultRequestListeners,
engine,
isLoggingRequestOriginsEnabled,
logLevel);
}
Glide创建代码，主要是对register对象调用append,register函数，设置一些参数，这些参数主要是对后边图片解析，加载
在Glide创建过程中，可以了解到在GlideBuilder中创建了RequestManagerRetriever，获取RequestManger对象需要调用RequestMangerRetriever.get方法
@NonNull
public RequestManager get(@NonNull Activity activity) {
if (Util.isOnBackgroundThread()) {
return get(activity.getApplicationContext());
} else {
assertNotDestroyed(activity);
android.app.FragmentManager fm = activity.getFragmentManager();
return fragmentGet(
activity, fm, /*parentHint=*/ null, isActivityVisible(activity));
}
}
@Deprecated
@NonNull
private RequestManager fragmentGet(@NonNull Context context,
@NonNull android.app.FragmentManager fm,
@Nullable android.app.Fragment parentHint,
boolean isParentVisible) {
RequestManagerFragment current = getRequestManagerFragment(fm, parentHint, isParentVisible);
RequestManager requestManager = current.getRequestManager();
if (requestManager == null) {
// TODO(b/27524013): Factor out this Glide.get() call.
Glide glide = Glide.get(context);
requestManager =
factory.build(
glide, current.getGlideLifecycle(), current.getRequestManagerTreeNode(), context);
current.setRequestManager(requestManager);
}
return requestManager;
}
@NonNull
private RequestManagerFragment getRequestManagerFragment(
@NonNull final android.app.FragmentManager fm,
@Nullable android.app.Fragment parentHint,
boolean isParentVisible) {
RequestManagerFragment current = (RequestManagerFragment) fm.findFragmentByTag(FRAGMENT_TAG);
if (current == null) {
current = pendingRequestManagerFragments.get(fm);
if (current == null) {
current = new RequestManagerFragment();
current.setParentFragmentHint(parentHint);
if (isParentVisible) {
current.getGlideLifecycle().onStart();
}
pendingRequestManagerFragments.put(fm, current);
fm.beginTransaction().add(current, FRAGMENT_TAG).commitAllowingStateLoss();
handler.obtainMessage(ID_REMOVE_FRAGMENT_MANAGER, fm).sendToTarget();
}
}
return current;
}
这几个方法主要是获取到RequestManagerFragment，再获取RequestManager. getRequestManagerFragment()方法中，获取或者创建RequestManagerFragment，也就是在 Activity中添加无视图的Fragment。获取到Fragment后，会获取Fragment中的RequestManager，如果RequestManager为NULL，就会通过factory进行创建。
创建方法中会将fragment中lifecycle传入到RequestManager中， 这里涉及到一个观察者模式。Fragment中有ActivityFragmentLifecycle对象，RequestManger实现LifecycleListener,在RequestManger中将自己添加到lifecycle的lifecycleListeners集合中，从而完成了图片加载框架与Activity 生命周期的绑定。，当lifecycle生命周期方法被执行人，他的所有listener也会执行对应的方法，也就是RequestManager对应的方法就会被执行
@Override
public synchronized void onStart() {
resumeRequests();
targetTracker.onStart();
}
@Override
public synchronized void onStop() {
pauseRequests();
targetTracker.onStop();
}
@Override
public synchronized void onDestroy() {
targetTracker.onDestroy();
for (Target target : targetTracker.getAll()) {
clear(target);
}
targetTracker.clear();
requestTracker.clearRequests();
lifecycle.removeListener(this);
lifecycle.removeListener(connectivityMonitor);
mainHandler.removeCallbacks(addSelfToLifecycle);
glide.unregisterRequestManager(this);
}
/**
* Attempts to always load the resource as a {@link android.graphics.Bitmap}, even if it could
* actually be animated.
*
* @return A new request builder
最终会有这样的RequestTracker来对Request请求进行操作，了解一下RequestTracker
public class RequestTracker {
private static final String TAG = "RequestTracker";
//保存当前所有Request请求集合
private final Set requests =
Collections.newSetFromMap(new WeakHashMap());
@SuppressWarnings("MismatchedQueryAndUpdateOfCollection")
private final List pendingRequests = new ArrayList<>();
private boolean isPaused;
/**
* Starts tracking the given request.
*/
public void runRequest(@NonNull Request request) {
//添加到集合并执行请求
requests.add(request);
if (!isPaused) {
request.begin();
} else {
request.clear();
if (Log.isLoggable(TAG, Log.VERBOSE)) {
Log.v(TAG, "Paused, delaying request");
}
pendingRequests.add(request);
}
}
@VisibleForTesting
void addRequest(Request request) {
requests.add(request);
}
public boolean clearRemoveAndRecycle(@Nullable Request request) {
return clearRemoveAndMaybeRecycle(request, /*isSafeToRecycle=*/ true);
}
private boolean clearRemoveAndMaybeRecycle(@Nullable Request request, boolean isSafeToRecycle) {
if (request == null) {
return true;
}
boolean isOwnedByUs = requests.remove(request);
// Avoid short circuiting.
isOwnedByUs = pendingRequests.remove(request) || isOwnedByUs;
if (isOwnedByUs) {
request.clear();
if (isSafeToRecycle) {
request.recycle();
}
}
return isOwnedByUs;
}
/**
* Returns {@code true} if requests are currently paused, and {@code false} otherwise.
*/
public boolean isPaused() {
return isPaused;
}
/**
* Stops any in progress requests.
*/
public void pauseRequests() {
isPaused = true;
for (Request request : Util.getSnapshot(requests)) {
if (request.isRunning()) {
request.clear();
pendingRequests.add(request);
}
}
}
/** Stops any in progress requests and releases bitmaps associated with completed requests. */
public void pauseAllRequests() {
isPaused = true;
for (Request request : Util.getSnapshot(requests)) {
if (request.isRunning() || request.isComplete()) {
request.clear();
pendingRequests.add(request);
}
}
}
/**
* Starts any not yet completed or failed requests.
*/
public void resumeRequests() {
isPaused = false;
for (Request request : Util.getSnapshot(requests)) {
if (!request.isComplete() && !request.isRunning()) {
request.begin();
}
}
pendingRequests.clear();
}
public void clearRequests() {
for (Request request : Util.getSnapshot(requests)) {
clearRemoveAndMaybeRecycle(request, /*isSafeToRecycle=*/ false);
}
pendingRequests.clear();
}
public void restartRequests() {
for (Request request : Util.getSnapshot(requests)) {
if (!request.isComplete() && !request.isCleared()) {
request.clear();
if (!isPaused) {
request.begin();
} else {
// Ensure the request will be restarted in onResume.
pendingRequests.add(request);
}
}
}
}
@Override
public String toString() {
return super.toString() + "{numRequests=" + requests.size() + ", isPaused=" + isPaused + "}";
}
}
以上代码可以了解到，RequestTracker对所有Request请求进行了保存，并且提供相应操作方法，如begin();
以上基本就是获取RequestManager整个流程。用一张图总结一下
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