Glide系列-生命周期的监听

1.Glide.with

public class Glide implements ComponentCallbacks2 {public static RequestManager with(@NonNull FragmentActivity activity) {return getRetriever(activity).get(activity);}}

2.RequestManagerRetriever.get

public class RequestManagerRetriever implements Handler.Callback {public RequestManager get(@NonNull FragmentActivity activity) {if (Util.isOnBackgroundThread()) {//在后台线程return get(activity.getApplicationContext());}assertNotDestroyed(activity);frameWaiter.registerSelf(activity);boolean isActivityVisible = isActivityVisible(activity);Glide glide = Glide.get(activity.getApplicationContext());return lifecycleRequestManagerRetriever.getOrCreate(activity,glide,activity.getLifecycle(),activity.getSupportFragmentManager(),isActivityVisible);}}

3.LifecycleRequestManagerRetriever.getOrCreate

• 在获得RequestManager的时候，调用new LifecycleLifecycle
• RequestManager 与 Activity获得Fragment的Lifecycle对应

final class LifecycleRequestManagerRetriever {RequestManager getOrCreate(Context context,Glide glide,final Lifecycle lifecycle,FragmentManager childFragmentManager,boolean isParentVisible) {//一个Lifecycle对应一个RequestManagerRequestManager result = getOnly(lifecycle);if (result == null) {//result为null，才会去创建LifecycleLifecycleLifecycleLifecycle glideLifecycle = new LifecycleLifecycle(lifecycle);}}}

4.LifecycleLifecycle

• LifecycleLifecycle初始化的时候，给Activity或者Fragment的Lifecycle设置生命周期的监听
• 添加自定义的LifecycleListener
• 在各个生命周期的回调里调用自定义的LifecycleListener的对应的方法

final class LifecycleLifecycle implements Lifecycle, LifecycleObserver {@NonNullprivate final Set lifecycleListeners = newHashSet();@NonNull private final androidx.lifecycle.Lifecycle lifecycle;LifecycleLifecycle(androidx.lifecycle.Lifecycle lifecycle) {//这里是activity.getLifecycle()或者fragment.getLifecycle()，所以//这里相当于设置了Activity或者Fragment的生命周期的监听。this.lifecycle = lifecycle;lifecycle.addObserver(this); //给Lifecycle注册LifecycleObserver }@OnLifecycleEvent(Event.ON_START)public void onStart(@NonNull LifecycleOwner owner) {for (LifecycleListener lifecycleListener : Util.getSnapshot(lifecycleListeners)) {lifecycleListener.onStart(); //Activity或者Fragment的onStart的时候执行}}@OnLifecycleEvent(Event.ON_STOP)public void onStop(@NonNull LifecycleOwner owner) {for (LifecycleListener lifecycleListener : Util.getSnapshot(lifecycleListeners)) {lifecycleListener.onStop(); //Activity或者Fragment的onStop的时候执行}}@OnLifecycleEvent(Event.ON_DESTROY)public void onDestroy(@NonNull LifecycleOwner owner) {for (LifecycleListener lifecycleListener : Util.getSnapshot(lifecycleListeners)){lifecycleListener.onDestroy();}owner.getLifecycle().removeObserver(this); //移除掉生命周期的监听}@Overridepublic void addListener(@NonNull LifecycleListener listener) {lifecycleListeners.add(listener); //添加自定义的LifecycleListener if (lifecycle.getCurrentState() == State.DESTROYED) {listener.onDestroy();} else if (lifecycle.getCurrentState().isAtLeast(State.STARTED)) {listener.onStart();} else {listener.onStop();}}@Overridepublic void removeListener(@NonNull LifecycleListener listener) {lifecycleListeners.remove(listener);//移除自定义的LifecycleListener }}

5.总结

所以在调用Glide.with的时候，就给Activity或者fragment添加了生命周期监听的observer