Glide會根據(jù)頁面（Activity钩蚊、Fragment）的生命周期锻霎，適時的開始、取消圖片加載事富。那么問題來了剑勾，頁面的生命周期事件是如何從頁面?zhèn)鬟f到Glide中的呢？
Glide.with(Activity)會調(diào)用 RequestManagerRetriver.get(Activity) 返回RequestManager赵颅。在 RequestManagerRetriver.get(Activity) 中虽另， 會 new 出來一個 RequestManagerFragment，并將其add到該Activity對應(yīng)的FragmentManager中饺谬，通過觀察 RequestManagerFragment 的Lifecycle捂刺，進(jìn)而觀察 對應(yīng)Activity的 Lifecycle谣拣。
RequestManagerFragment 持有 ActivityFragmentLifecycle，生命周期事件會下發(fā)到ActivityFragmentLifecycle中族展，進(jìn)而被傳遞到實現(xiàn)了LifecycleListener 接口的 RequestManager 中
Lifecycle event spread logic
@startuml
class RequestManager {
TargetTracker targetTracker
}
class RequestManagerFragment {
ActivityFragmentLifecycle lifecycle
}
class ActivityFragmentLifecycle {
Set<LifecycleListener> lifecycleListeners
}
interface LifecycleListener {
void onStart()
void onStop()
void onDestroy()
}
class TargetTracker {
Set<Target<?>> targets
}
interface Target {
}
LifecycleListener <-- RequestManager: implement
LifecycleListener <-- TargetTracker: implement
LifecycleListener <-- Target: implement
'ActivityFragmentLifecycle --> LifecycleListener: lifecycle event
RequestManagerFragment --> ActivityFragmentLifecycle: lifecycle event
ActivityFragmentLifecycle --> RequestManager: lifecycle event
RequestManager --> TargetTracker: lifecycle event
TargetTracker --> Target: lifecycle event
@enduml
RequestManagerFragment 被新建出來并被添加到 Activity 對應(yīng)的 Activity 中
@NonNull
private RequestManagerFragment getRequestManagerFragment(
@NonNull final android.app.FragmentManager fm,
@Nullable android.app.Fragment parentHint,
boolean isParentVisible) {
//..
current = new RequestManagerFragment();
//..
fm.beginTransaction().add(current, FRAGMENT_TAG).commitAllowingStateLoss();
}
}
return current;
}
RequestManager structure
RequestManager structure
RequestManagerFragment
ActivityFragmentLifecycle
ActivityFragmentLifecycle
LifecycleListener
LifecycleListener
