Glide.with(this).load("").into();
with()方法：包含Glide的初始化， 以及RequestManager的初始化
Glide内：RequestManager的初始化
@NonNull
public static RequestManager with(@NonNull FragmentActivity activity) {
return getRetriever(activity).get(activity);
}
@NonNull
public RequestManager get(@NonNull FragmentActivity activity) {
if (Util.isOnBackgroundThread()) {
return this.get(activity.getApplicationContext());
} else {
assertNotDestroyed(activity);
androidx.fragment.app.FragmentManager fm = activity.getSupportFragmentManager();
return this.supportFragmentGet(activity, fm, (Fragment)null, isActivityVisible(activity));
}
}
@NonNull
private RequestManager supportFragmentGet(@NonNull Context context, @NonNull androidx.fragment.app.FragmentManager fm, @Nullable Fragment parentHint, boolean isParentVisible) {
SupportRequestManagerFragment current = this.getSupportRequestManagerFragment(fm, parentHint, isParentVisible);//1.生成一个fragment
RequestManager requestManager = current.getRequestManager();
if (requestManager == null) {
Glide glide = Glide.get(context);
requestManager = this.factory.build(glide, current.getGlideLifecycle(), current.getRequestManagerTreeNode(), context);//2.使用工厂RequestManagerFactory生成一个RequestManager
current.setRequestManager(requestManager);//3.将requestManager与生成的SupportRequestManagerFragment进行绑定
}
return requestManager;
}
以Activity为例子：
1.首先会为当前activity生成绑定一个SupportRequestManagerFragment
2.使用工厂RequestManagerFactory生成一个RequestManager，参数分别是Gilde，LifeCycle, SupportFragmentRequestManagerTreeNode()，上下文本身（这里指的activity）
3.将requestManager与生成的SupportRequestManagerFragment进行绑定
laod()方法：-> 返回一个RequestBuilder<Drawable>
RequestManager内：
public RequestBuilder<Drawable> load(@Nullable String string) {
return asDrawable().load(string);
}
public RequestBuilder<Drawable> asDrawable() {
return as(Drawable.class);
}
public <ResourceType> RequestBuilder<ResourceType> as(
@NonNull Class<ResourceType> resourceClass) { //
return new RequestBuilder<>(glide, this, resourceClass, context);//1.生成一个RequestBilder 参数分别是gilde ResuestManager,Drawable.class，context上下文（activity）
}
RequestBuilder内:
@Override
public RequestBuilder<TranscodeType> load(@Nullable Object model) {
return loadGeneric(model);
}
@NonNull
private RequestBuilder<TranscodeType> loadGeneric(@Nullable Object model) {
this.model = model;
isModelSet = true;
return this;
}
这里以load(参数为string资源连接)为例：
1.生成一个RequestBilder 参数分别是gilde ResuestManager,Drawable.class，context上下文（activity）
2.将传入的资源链接（图片链接"xxx"）赋值给内部私有变量private Object model 并返回RequestBilder
into()方法：
RequestBilder内：into参数以ImageView为例
public ViewTarget<ImageView, TranscodeType> into(@NonNull ImageView view) {
Util.assertMainThread();//UI操作必须是在UI线程进行
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()) { //根据设置的scaleType初始化不同的Options
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), //返回一个DrawableImageViewTarget
/*targetListener=*/ null,
requestOptions);
}
private <Y extends Target<TranscodeType>> Y into(
@NonNull Y target, // 类型为DrawableImageViewTarget
@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();
//参数 target==DrawableImageViewTarget， targetListener == null
Request request = buildRequest(target, targetListener, options); //1.构建并返回一个SingleRequest
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);//2.给目标imageView设置tag标记
requestManager.track(target, request); //3.运行Request 开始从三级缓存以及网络中请求数据
return target;
}
into方法内部三步：
1.构建并返回一个SingleRequest
2.给目标imageView设置tag标记
3.运行Request 开始从三级缓存以及网络中请求数据
真正开始请求数据的地方：3. requestManager.track(target, request) 参数为返回一个DrawableImageViewTarget以及SingleRequest
RequestManager内部：
void track(@NonNull Target<?> target, @NonNull Request request) {
targetTracker.track(target);
requestTracker.runRequest(request); //执行request
}
RequestTracker内：
public void runRequest(@NonNull Request request) {
requests.add(request);
if (!isPaused) {
request.begin(); //SingleRequest begin()
} else {
if (Log.isLoggable(TAG, Log.VERBOSE)) {
Log.v(TAG, "Paused, delaying request");
}
pendingRequests.add(request);
}
}
SingleRequest内：
@Override
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)) { //判断ImageView宽高是否正确
onSizeReady(overrideWidth, overrideHeight); //开始加载
} 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));
}
}
@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; //修改加载的状态为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));
}
//真正开始加载数据到来
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));
}
}
最后执行的方法来到Engine.load();
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;
EngineKey key = keyFactory.buildKey(model, signature, width, height, transformations,
resourceClass, transcodeClass, options);
//1.首先从正在活动的视图资源ActiveResources中开始取
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;
}
//2.从LruCache内存缓存中取
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;
}
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); //3.从硬盘缓存中取
if (VERBOSE_IS_LOGGABLE) {
logWithTimeAndKey("Started new load", startTime, key);
}
return new LoadStatus(cb, engineJob);
}
1.首先从正在活动的视图资源ActiveResources中开始取
2.从LruCache内存缓存中取
3.从硬盘缓存中取
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