在http://blog.csdn.net/kc58236582/article/details/52794846博客中我们已经讲了开机动画的大致流程，这里我们就Launcher启动后，Launcher的线程闲的时候在ActivityThread调用AMS的activityIdle方法。
在分析消息机制 空闲消息处理器中http://blog.csdn.net/kc58236582/article/details/52919904，我们知道在消息线程空闲时会调用IdleHandler的queueIdle方法，这里我们来看ActivityThread中的IdleHandler，是在ActivityThread的handleResumeActivity函数中有下面一段代码，调用了MessageQueue的addIdleHandler函数。
......
if (!r.onlyLocalRequest) {
r.nextIdle = mNewActivities;
mNewActivities = r;
if (localLOGV) Slog.v(
TAG, "Scheduling idle handler for " + r);
Looper.myQueue().addIdleHandler(new Idler());
}
......在Idler的queueIdle函数中调用了AMS的activityIdle函数，我们来看下，获取ActivityStack后调用了activityIdleInternalLocked函数。
@Override
public final void activityIdle(IBinder token, Configuration config, boolean stopProfiling) {
final long origId = Binder.clearCallingIdentity();
synchronized (this) {
ActivityStack stack = ActivityRecord.getStackLocked(token);//得到ActivityStack
if (stack != null) {
ActivityRecord r =
mStackSupervisor.activityIdleInternalLocked(token, false, config);
if (stopProfiling) {
if ((mProfileProc == r.app) && (mProfileFd != null)) {
try {
mProfileFd.close();
} catch (IOException e) {
}
clearProfilerLocked();
}
}
}
}
Binder.restoreCallingIdentity(origId);
}看如下函数，我们先根据token来得到其ActivityRecord，然后将ActivityRecord的idle置为true。如果是isFrontStack调用checkFinishBootingLocked函数。
final ActivityRecord activityIdleInternalLocked(final IBinder token, boolean fromTimeout,
Configuration config) {
if (DEBUG_ALL) Slog.v(TAG, "Activity idle: " + token);
ArrayList<ActivityRecord> stops = null;
ArrayList<ActivityRecord> finishes = null;
ArrayList<UserState> startingUsers = null;
int NS = 0;
int NF = 0;
boolean booting = false;
boolean activityRemoved = false;
ActivityRecord r = ActivityRecord.forTokenLocked(token);
if (r != null) {
if (DEBUG_IDLE) Slog.d(TAG_IDLE, "activityIdleInternalLocked: Callers="
+ Debug.getCallers(4));
mHandler.removeMessages(IDLE_TIMEOUT_MSG, r);
r.finishLaunchTickingLocked();
if (fromTimeout) {
reportActivityLaunchedLocked(fromTimeout, r, -1, -1);
}
// This is a hack to semi-deal with a race condition
// in the client where it can be constructed with a
// newer configuration from when we asked it to launch.
// We'll update with whatever configuration it now says
// it used to launch.
if (config != null) {
r.configuration = config;
}
// We are now idle. If someone is waiting for a thumbnail from
// us, we can now deliver.
r.idle = true;//idle置为true
//Slog.i(TAG, "IDLE: mBooted=" + mBooted + ", fromTimeout=" + fromTimeout);
if (isFrontStack(r.task.stack) || fromTimeout) {
booting = checkFinishBootingLocked();
}
}
......checkFinishBootingLocked函数，如果AMS正在启动会调用其postFinishBooting函数
private boolean checkFinishBootingLocked() {
final boolean booting = mService.mBooting;
boolean enableScreen = false;
mService.mBooting = false;
if (!mService.mBooted) {
mService.mBooted = true;
enableScreen = true;
}
if (booting || enableScreen) {
mService.postFinishBooting(booting, enableScreen);
}
return booting;
}AMS的postFinishBooting函数发送FINISH_BOOTING_MSG消息
void postFinishBooting(boolean finishBooting, boolean enableScreen) {
mHandler.sendMessage(mHandler.obtainMessage(FINISH_BOOTING_MSG,
finishBooting ? 1 : 0, enableScreen ? 1 : 0));
}我们再来看消息处理，当finishBooting为true，就调用finishBooting函数，这个函数中会发送一些广播，以及将SystemService启动到PHASE_BOOT_COMPLETED阶段。
case FINISH_BOOTING_MSG: {
if (msg.arg1 != 0) {
finishBooting();
}
if (msg.arg2 != 0) {
enableScreenAfterBoot();
}
break;
}当enableScreen为true会调用enableScreenAfterBoot函数，会在这个函数中调用WMS的enableScreenAfterBoot函数
void enableScreenAfterBoot() {
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_ENABLE_SCREEN,
SystemClock.uptimeMillis());
mWindowManager.enableScreenAfterBoot();
synchronized (this) {
updateEventDispatchingLocked();
}
}在WMS的enableScreenAfterBoot方法又会调用performEnableScreen方法，这个方法会调用SurfaceFlinger的Binder
public void performEnableScreen() {
synchronized(mWindowMap) {
if (mDisplayEnabled) {
return;
}
if (!mSystemBooted && !mShowingBootMessages) {
return;
}
// Don't enable the screen until all existing windows have been drawn.
if (!mForceDisplayEnabled && checkWaitingForWindowsLocked()) {
return;
}
if (!mBootAnimationStopped) {
// Do this one time.
try {
IBinder surfaceFlinger = ServiceManager.getService("SurfaceFlinger");
if (surfaceFlinger != null) {
//Slog.i(TAG, "******* TELLING SURFACE FLINGER WE ARE BOOTED!");
Parcel data = Parcel.obtain();
data.writeInterfaceToken("android.ui.ISurfaceComposer");
surfaceFlinger.transact(IBinder.FIRST_CALL_TRANSACTION, // BOOT_FINISHED
data, null, 0);
data.recycle();
}
} catch (RemoteException ex) {
Slog.e(TAG, "Boot completed: SurfaceFlinger is dead!");
}
mBootAnimationStopped = true;
}
......FIRST_CALL_TRANSACTION就是BOOT_FINISHED
class BnSurfaceComposer: public BnInterface<ISurfaceComposer> {
public:
enum {
// Note: BOOT_FINISHED must remain this value, it is called from
// Java by ActivityManagerService.
BOOT_FINISHED = IBinder::FIRST_CALL_TRANSACTION,我们再来看ISurfaceComposer.cpp对BOOT_FINISHED的处理，会调用bootFinished函数。
case BOOT_FINISHED: {
CHECK_INTERFACE(ISurfaceComposer, data, reply);
bootFinished();
return NO_ERROR;
}bootFinished会计算开机的时间，然后将service.bootanim.exit属性设为1，这样bootanim会结束，这样开机动画结束。
void SurfaceFlinger::bootFinished()
{
const nsecs_t now = systemTime();
const nsecs_t duration = now - mBootTime;
ALOGI("Boot is finished (%ld ms)", long(ns2ms(duration)) );
mBootFinished = true;
// wait patiently for the window manager death
const String16 name("window");
sp<IBinder> window(defaultServiceManager()->getService(name));
if (window != 0) {
window->linkToDeath(static_cast<IBinder::DeathRecipient*>(this));
}
// stop boot animation
// formerly we would just kill the process, but we now ask it to exit so it
// can choose where to stop the animation.
property_set("service.bootanim.exit", "1");
char boot_exit_value[32];
property_get("service.bootanim.exit", boot_exit_value, "0");
ALOGD("The service.bootanim.exit property value is %d", atoi(boot_exit_value));
}