資訊專欄INFORMATION COLUMN
摘要：版本問題如何實(shí)現(xiàn)與生命周期的綁定如何實(shí)現(xiàn)緩存如何實(shí)現(xiàn)圖片壓縮如何實(shí)現(xiàn)與生命周期的綁定創(chuàng)建將其與傳入的生命周期綁定這樣做的好處是當(dāng)時(shí)，也會(huì)做相應(yīng)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(diào)用創(chuàng)建的與綁定，這樣創(chuàng)建的的生命周
版本4.9.0
問題Glide如何實(shí)現(xiàn)與生命周期的綁定？
Glide如何實(shí)現(xiàn)緩存？
Glide如何實(shí)現(xiàn)圖片壓縮?
Glide如何實(shí)現(xiàn)與生命周期的綁定?創(chuàng)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(dāng)Activity/Fragment stop/destroy時(shí)，RequestManager也會(huì)做相應(yīng)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(diào)用,創(chuàng)建的RequestManger與 Application Context綁定，這樣創(chuàng)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(nèi)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(chuàng)建了并對(duì)外提供ActivityFragmentLifecycle對(duì)象,
創(chuàng)建RequestManager時(shí)，傳入ActivityFragmentLifecycle對(duì)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(shí)現(xiàn)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(shí)現(xiàn)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(shí)現(xiàn)緩存？
提供了兩個(gè)內(nèi)存緩存,分別存儲(chǔ)強(qiáng)弱引用
弱引用的緩存: 存放正在使用的
強(qiáng)引用的緩存: 存放沒有使用的
