資訊專欄INFORMATION COLUMN
摘要：版本問題如何實現與生命周期的綁定如何實現緩存如何實現圖片壓縮如何實現與生命周期的綁定創建將其與傳入的生命周期綁定這樣做的好處是當時，也會做相應操作，如停掉圖片加載綁定首先無論傳入的是什么，只要是在子線程中調用創建的與綁定，這樣創建的的生命周
版本4.9.0
問題Glide如何實現與生命周期的綁定？
Glide如何實現緩存？
Glide如何實現圖片壓縮?
Glide如何實現與生命周期的綁定?創建RequestManger,將其與with()傳入 Activity, Fragment的生命周期綁定,
這樣做的好處是當Activity/Fragment stop/destroy時，RequestManager也會做相應操作，如停掉圖片加載
綁定Application Context
首先無論with()傳入的是什么，只要是在子線程中調用,創建的RequestManger與 Application Context綁定，這樣創建的RequestMangager的生命周期與
if (Util.isOnBackgroundThread()) {
return get(fragment.getActivity().getApplicationContext());
} else {
... ...
}
這樣做的目的是防止Activity,Fragment內存泄漏
Activity與FramgentActivity
class RequestManagerFragment {
... ...
private final ActivityFragmentLifecycle lifecycle;
@Override
public void onStart() {
super.onStart();
lifecycle.onStart();
}
@Override
public void onStop() {
super.onStop();
lifecycle.onStop();
}
@Override
public void onDestroy() {
super.onDestroy();
lifecycle.onDestroy();
unregisterFragmentWithRoot();
}
... ...
}
class ActivityFragmentLifecycle implements Lifecycle {
@Override
public void addListener(@NonNull LifecycleListener listener) {
lifecycleListeners.add(listener);
if (isDestroyed) {
listener.onDestroy();
} else if (isStarted) {
listener.onStart();
} else {
listener.onStop();
}
}
void onStart() {
isStarted = true;
for (LifecycleListener lifecycleListener : Util.getSnapshot(lifecycleListeners)) {
lifecycleListener.onStart();
}
}
void onStop() {
isStarted = false;
for (LifecycleListener lifecycleListener : Util.getSnapshot(lifecycleListeners)) {
lifecycleListener.onStop();
}
}
void onDestroy() {
isDestroyed = true;
for (LifecycleListener lifecycleListener : Util.getSnapshot(lifecycleListeners)) {
lifecycleListener.onDestroy();
}
}
}
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);
}
RequestManagerFragment中創建了并對外提供ActivityFragmentLifecycle對象,
創建RequestManager時，傳入ActivityFragmentLifecycle對象
RequestManager(
Glide glide,
Lifecycle lifecycle,
RequestManagerTreeNode treeNode,
RequestTracker requestTracker,
ConnectivityMonitorFactory factory,
Context context) {
... ...
lifecycle.addListener(this);
... ...
}
@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);
}
這樣RequestManger.onStart(),onStop(),onDestroy()與Activity的生命周期通過Activity綁定的空Fragment實現了綁定
Fragment
與Activity的綁定方式類似，
FragmentManager fm = fragment.getChildFragmentManager();
將RequestManger.onStart(),onStop(),onDestroy()與Fragment的生命周期通過Fragment綁定的空Fragment實現的綁定
View
通過View可以獲取它所在的Activity 或 Fragment
Activity activity = findActivity(view.getContext());
@Nullable
private Activity findActivity(@NonNull Context context) {
if (context instanceof Activity) {
return (Activity) context;
} else if (context instanceof ContextWrapper) {
return findActivity(((ContextWrapper) context).getBaseContext());
} else {
return null;
}
}
@Nullable
private Fragment findSupportFragment(@NonNull View target, @NonNull
FragmentActivity activity) {
tempViewToSupportFragment.clear();
findAllSupportFragmentsWithViews(
activity.getSupportFragmentManager().getFragments(), tempViewToSupportFragment);
Fragment result = null;
View activityRoot = activity.findViewById(android.R.id.content);
View current = target;
while (!current.equals(activityRoot)) {
result = tempViewToSupportFragment.get(current);
if (result != null) {
break;
}
if (current.getParent() instanceof View) {
current = (View) current.getParent();
} else {
break;
}
}
tempViewToSupportFragment.clear();
return result;
}
Context
通過Context獲取Activity or FragmentActivity or Application Context
if (context == null) {
throw new IllegalArgumentException("You cannot start a load on a nullContext");
} else if (Util.isOnMainThread() && !(context instanceof Application)){
if (context instanceof FragmentActivity) {
return get((FragmentActivity) context);
} else if (context instanceof Activity) {
return get((Activity) context);
} else if (context instanceof ContextWrapper) {
return get(((ContextWrapper) context).getBaseContext());
}
}
return getApplicationManager(context);
Glide如何實現緩存？
提供了兩個內存緩存,分別存儲強弱引用
弱引用的緩存: 存放正在使用的
強引用的緩存: 存放沒有使用的
