[置顶] Android 7.1.1 锁屏界面启动流程

      前几天遇到一个低概率复现锁屏界面不显示，只显示状态栏的问题，跟了下锁屏界面启动显示的流程，在这分享下，也方便以后自己查看。前面简单介绍了下Zygote启动流程， Zygote进程启动后会首先创建一个SystemServer进程，SystemServer进程在调用startOtherServices同时也会调用WindowManagerService的systemReady()方法

//frameworks/base/services/java/com/android/server/SystemServer.java
private void startOtherServices() {
...
wm = WindowManagerService.main(context, inputManager,
mFactoryTestMode != FactoryTest.FACTORY_TEST_LOW_LEVEL,
!mFirstBoot, mOnlyCore);
...
try {
wm.systemReady();
Slog.i("jason11", "SystemServer wm.systemReady");
} catch (Throwable e) {
reportWtf("making Window Manager Service ready", e);
}
...
}
 在WindowManagerService中直接调用了PhoneWindowManager里的systemReady()

//frameworks/base/services/core/java/com/android/server/wm/WindowManagerService.java
//final WindowManagerPolicy mPolicy = new PhoneWindowManager();
public void systemReady() {
mPolicy.systemReady();
}在PhoneWindowManager的systemReady()会根据一个Boolean值bindKeyguardNow来决定是否绑定keyguard
service
//frameworks/base/services/core/java/com/android/server/policy/PhoneWindowManager.java
/** {@inheritDoc} */
@Override
public void systemReady() {
mKeyguardDelegate = new KeyguardServiceDelegate(mContext);
mKeyguardDelegate.onSystemReady();

readCameraLensCoverState();
updateUiMode();
boolean bindKeyguardNow;
synchronized (mLock) {
updateOrientationListenerLp();
mSystemReady = true;
mHandler.post(new Runnable() {
@Override
public void run() {
updateSettings();
}
});

bindKeyguardNow = mDeferBindKeyguard;
if (bindKeyguardNow) {
// systemBooted ran but wasn't able to bind to the Keyguard, we'll do it now.
mDeferBindKeyguard = false;
}
}
if (bindKeyguardNow) {
mKeyguardDelegate.bindService(mContext);
mKeyguardDelegate.onBootCompleted();
}
mSystemGestures.systemReady();
}
看到这里，可能会想到如果bindKeyguardNow为false就会不绑定，后面通过继续跟踪发现在PhoneWindowManager的systemBooted()里也会去绑定keyguard service，如果在systemBooted里绑定了就不在systemReady里再去绑定，自己测试的时候是在systemBooted绑定的

//frameworks/base/services/core/java/com/android/server/policy/PhoneWindowManager.java
/** {@inheritDoc} */
@Override
public void systemBooted() {
boolean bindKeyguardNow = false;
synchronized (mLock) {
// Time to bind Keyguard; take care to only bind it once, either here if ready or
// in systemReady if not.
if (mKeyguardDelegate != null) {
bindKeyguardNow = true;
} else {
// Because mKeyguardDelegate is null, we know that the synchronized block in
// systemReady didn't run yet and setting this will actually have an effect.
mDeferBindKeyguard = true;
}
}
if (bindKeyguardNow) {
mKeyguardDelegate.bindService(mContext);
mKeyguardDelegate.onBootCompleted();
}
synchronized (mLock) {
mSystemBooted = true;
}
startedWakingUp();
screenTurningOn(null);
screenTurnedOn();
}
下面就通过如下的时序图看看是如何调用到systemBooted的，就不在一步步跟了



通过上面的分析知道，无论是在systemReady或systemBooted，都调用了KeyguardServiceDelegate对象的bindService方法，下面就以这个方法开始，看看锁屏界面是怎么显示出来的，先看看下面的时序图，再来分步讲解



1、先来看看在KeyguardServiceDelegate如何绑定KeyguardService的

//frameworks/base/services/core/java/com/android/server/policy/keyguard/KeyguardServiceDelegate.java
public class KeyguardServiceDelegate {
...
public void bindService(Context context) {
Intent intent = new Intent();
final Resources resources = context.getApplicationContext().getResources();

final ComponentName keyguardComponent = ComponentName.unflattenFromString(
resources.getString(com.android.internal.R.string.config_keyguardComponent));
intent.setComponent(keyguardComponent);

if (!context.bindServiceAsUser(intent, mKeyguardConnection,
Context.BIND_AUTO_CREATE, UserHandle.OWNER)) {
Log.v(TAG, "*** Keyguard: can't bind to " + keyguardComponent);
mKeyguardState.showing = false;
mKeyguardState.showingAndNotOccluded = false;
mKeyguardState.secure = false;
synchronized (mKeyguardState) {
// TODO: Fix synchronisation model in this class. The other state in this class
// is at least self-healing but a race condition here can lead to the scrim being
// stuck on keyguard-less devices.
mKeyguardState.deviceHasKeyguard = false;
hideScrim();
}
} else {
if (DEBUG) Log.v(TAG, "*** Keyguard started");
}
}
...
}在bindService中调用了bindServiceAsUser绑定指定intent的service，config_keyguardComponent的定义如下
//frameworks/base/core/res/res/values/config.xml
<!-- Keyguard component -->
<string name="config_keyguardComponent" translatable="false">com.android.systemui/com.android.systemui.keyguard.KeyguardService</string>当绑定成功后会调用mKeyguardConnection里的onServiceConnected方法
//frameworks/base/services/core/java/com/android/server/policy/keyguard/KeyguardServiceDelegate.java
public class KeyguardServiceDelegate {
...
private final ServiceConnection mKeyguardConnection = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
if (DEBUG) Log.v(TAG, "*** Keyguard connected (yay!)");
mKeyguardService = new KeyguardServiceWrapper(mContext,
IKeyguardService.Stub.asInterface(service));
if (mKeyguardState.systemIsReady) {
// If the system is ready, it means keyguard crashed and restarted.
mKeyguardService.onSystemReady();
// This is used to hide the scrim once keyguard displays.
if (mKeyguardState.interactiveState == INTERACTIVE_STATE_AWAKE) {
mKeyguardService.onStartedWakingUp();
}
if (mKeyguardState.screenState == SCREEN_STATE_ON
|| mKeyguardState.screenState == SCREEN_STATE_TURNING_ON) {
mKeyguardService.onScreenTurningOn(
new KeyguardShowDelegate(mDrawnListenerWhenConnect));
}
if (mKeyguardState.screenState == SCREEN_STATE_ON) {
mKeyguardService.onScreenTurnedOn();
}
mDrawnListenerWhenConnect = null;
}
if (mKeyguardState.bootCompleted) {
mKeyguardService.onBootCompleted();
}
if (mKeyguardState.occluded) {
mKeyguardService.setOccluded(mKeyguardState.occluded);
}
}

@Override
public void onServiceDisconnected(ComponentName name) {
if (DEBUG) Log.v(TAG, "*** Keyguard disconnected (boo!)");
mKeyguardService = null;
}

};
...
}当mKeyguardState.systemIsReady为true是，就会通过KeyguardServiceWrapper的实例mKeyguardService调用onSystemReady方法，在KeyguardServiceWrapper的onSystemReady里调用了上面刚刚绑定成功的KeyguardService的onSystemReady方法
//frameworks/base/services/core/java/com/android/server/policy/keyguard/KeyguardServiceWrapper.java
public class KeyguardServiceWrapper implements IKeyguardService {
...
@Override // Binder interface
public void onSystemReady() {
try {
mService.onSystemReady();
} catch (RemoteException e) {
Slog.w(TAG , "Remote Exception", e);
}
}
...
}

在KeyguardService的onSystemReady里调用了KeyguardViewMediator里的onSystemReady，在这里就不贴这个代码了，直接看看KeyguardViewMediator.onSystemReady这个里面干啥了

2、KeyguardViewMediator.onSystemReady

//frameworks/base/packages/SystemUI/src/com/android/systemui/keyguard/KeyguardViewMediator.java
public class KeyguardViewMediator extends SystemUI {
...
public void onSystemReady() {
mSearchManager = (SearchManager) mContext.getSystemService(Context.SEARCH_SERVICE);
synchronized (this) {
if (DEBUG) Log.d(TAG, "onSystemReady");
mSystemReady = true;
doKeyguardLocked(null);
mUpdateMonitor.registerCallback(mUpdateCallback);
}
// Most services aren't available until the system reaches the ready state, so we
// send it here when the device first boots.
maybeSendUserPresentBroadcast();
}
...
}
在这个方法里主要调用了doKeyguardLocked和注册了KeyguardUpdateMonitorCallback
3、通过调用doKeyguardLocked显示锁屏界面

//frameworks/base/packages/SystemUI/src/com/android/systemui/keyguard/KeyguardViewMediator.java
public class KeyguardViewMediator extends SystemUI {
...
private void doKeyguardLocked(Bundle options) {
// if another app is disabling us, don't show
if (!mExternallyEnabled) {
if (DEBUG) Log.d(TAG, "doKeyguard: not showing because externally disabled");

// note: we *should* set mNeedToReshowWhenReenabled=true here, but that makes
// for an occasional ugly flicker in this situation:
// 1) receive a call with the screen on (no keyguard) or make a call
// 2) screen times out
// 3) user hits key to turn screen back on
// instead, we reenable the keyguard when we know the screen is off and the call
// ends (see the broadcast receiver below)
// TODO: clean this up when we have better support at the window manager level
// for apps that wish to be on top of the keyguard
return;
}

// if the keyguard is already showing, don't bother
if (mStatusBarKeyguardViewManager.isShowing()) {
if (DEBUG) Log.d(TAG, "doKeyguard: not showing because it is already showing");
resetStateLocked();
return;
}

// if the setup wizard hasn't run yet, don't show
final boolean requireSim = !SystemProperties.getBoolean("keyguard.no_require_sim", false);
final boolean absent = SubscriptionManager.isValidSubscriptionId(
mUpdateMonitor.getNextSubIdForState(IccCardConstants.State.ABSENT));
final boolean disabled = SubscriptionManager.isValidSubscriptionId(
mUpdateMonitor.getNextSubIdForState(IccCardConstants.State.PERM_DISABLED));
final boolean lockedOrMissing = mUpdateMonitor.isSimPinSecure()
|| ((absent || disabled) && requireSim);

if (!lockedOrMissing && shouldWaitForProvisioning()) {
if (DEBUG) Log.d(TAG, "doKeyguard: not showing because device isn't provisioned"
+ " and the sim is not locked or missing");
return;
}

if (mLockPatternUtils.isLockScreenDisabled(KeyguardUpdateMonitor.getCurrentUser())
&& !lockedOrMissing) {
if (DEBUG) Log.d(TAG, "doKeyguard: not showing because lockscreen is off");
return;
}

if (mLockPatternUtils.checkVoldPassword(KeyguardUpdateMonitor.getCurrentUser())) {
if (DEBUG) Log.d(TAG, "Not showing lock screen since just decrypted");
// Without this, settings is not enabled until the lock screen first appears
setShowingLocked(false);
hideLocked();
mUpdateMonitor.reportSuccessfulStrongAuthUnlockAttempt();
return;
}

if (DEBUG) Log.d(TAG, "doKeyguard: showing the lock screen");
showLocked(options);
}
...
}
这段代码主要是在是否要显示锁屏之前做了5个判断：1.如果启用第三方锁屏界面，不显示原生界面；2.锁屏界面已经显示了话，重新更新下状态；3.如果第一次开机引导界面setup wizard 还没有运行，也先不显示；4.屏幕没有亮不显示；5.当前正在解密界面不显示。如果这几个条件都不满足，则调用showLocked显示锁屏界面。在showLocked通过mHandler发送Message，在handleMessage里“case
SHOW:”时调用handleShow
4、在handleShow里设置一些锁屏状态和显示锁屏界面

//frameworks/base/packages/SystemUI/src/com/android/systemui/keyguard/KeyguardViewMediator.java
public class KeyguardViewMediator extends SystemUI {
...
private void handleShow(Bundle options) {
synchronized (KeyguardViewMediator.this) {
if (!mSystemReady) {
if (DEBUG) Log.d(TAG, "ignoring handleShow because system is not ready.");
return;
} else {
if (DEBUG) Log.d(TAG, "handleShow");
}

setShowingLocked(true);
mStatusBarKeyguardViewManager.show(options);
mHiding = false;
mWakeAndUnlocking = false;
resetKeyguardDonePendingLocked();
mHideAnimationRun = false;
updateActivityLockScreenState();
adjustStatusBarLocked();
userActivity();

mShowKeyguardWakeLock.release();
}
mKeyguardDisplayManager.show();
}
...
}

5、通过调用StatusBarKeyguardViewManager的show重置当前状态显示keyguard

//frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/StatusBarKeyguardViewManager.java
public class StatusBarKeyguardViewManager {
...
public void show(Bundle options) {
mShowing = true;
mStatusBarWindowManager.setKeyguardShowing(true);
mScrimController.abortKeyguardFadingOut();
reset();
}
...
}
在reset里调用本类的showBouncerOrKeyguard，在这个方法里通过KeyguardBouncer的实例mBouncer调用prepare()，在prepare里调用了KeyguardHostView的showPrimarySecurityScreen
6、KeyguardSecurityContainer.showPrimarySecurityScreen

在KeyguardHostView的showPrimarySecurityScreen里调用KeyguardSecurityContainer的showPrimarySecurityScreen方法，如下

//frameworks/base/packages/Keyguard/src/com/android/keyguard/KeyguardSecurityContainer.java
public class KeyguardSecurityContainer extends FrameLayout implements KeyguardSecurityView {
...
void showPrimarySecurityScreen(boolean turningOff) {
SecurityMode securityMode = mSecurityModel.getSecurityMode();
if (DEBUG) Log.v(TAG, "showPrimarySecurityScreen(turningOff=" + turningOff + ")");
showSecurityScreen(securityMode);
}
...
}
在这个方法里调用了showSecurityScreen，根据mSecurityModel.getSecurityMode()获取的SecurityMode来显示不同界面，SecurityMode定义如下
//frameworks/base/packages/Keyguard/src/com/android/keyguard/KeyguardSecurityModel.java
public class KeyguardSecurityModel {
public enum SecurityMode {
Invalid, // NULL state
None, // No security enabled
Pattern, // Unlock by drawing a pattern.
Password, // Unlock by entering an alphanumeric password
PIN, // Strictly numeric password
SimPin, // Unlock by entering a sim pin.
SimPuk // Unlock by entering a sim puk
}
...
}

showSecurityScreen方法如下：

//frameworks/base/packages/Keyguard/src/com/android/keyguard/KeyguardSecurityContainer.java
public class KeyguardSecurityContainer extends FrameLayout implements KeyguardSecurityView {
...
private void showSecurityScreen(SecurityMode securityMode) {
if (DEBUG) Log.d(TAG, "showSecurityScreen(" + securityMode + ")");

if (securityMode == mCurrentSecuritySelection) return;

KeyguardSecurityView oldView = getSecurityView(mCurrentSecuritySelection);
KeyguardSecurityView newView = getSecurityView(securityMode);//根据securityMode获取对应的view

// Emulate Activity life cycle
if (oldView != null) {
oldView.onPause();
oldView.setKeyguardCallback(mNullCallback); // ignore requests from old view
}
if (securityMode != SecurityMode.None) {
newView.onResume(KeyguardSecurityView.VIEW_REVEALED);
newView.setKeyguardCallback(mCallback);
}

// Find and show this child.
final int childCount = mSecurityViewFlipper.getChildCount();

final int securityViewIdForMode = getSecurityViewIdForMode(securityMode);
for (int i = 0; i < childCount; i++) {
if (mSecurityViewFlipper.getChildAt(i).getId() == securityViewIdForMode) {
mSecurityViewFlipper.setDisplayedChild(i);
break;
}
}

mCurrentSecuritySelection = securityMode;
mSecurityCallback.onSecurityModeChanged(securityMode,
securityMode != SecurityMode.None && newView.needsInput());
}
...
}
到这里锁屏就启动完成了，这里简单总结一下：
   1. 在KeyguardServiceDelegate里绑定KeyguardService，并调用onSystemReady方法。
   2. KeyguardViewMediator里调用doKeyguardLocked来决定是否需要显示锁屏界面；如果显示则调用StatusBarKeyguardViewManager的show，最后调用到KeyguardHostView的showPrimarySecurityScreen()。
   3. 在KeyguardSecurityContainer的showPrimarySecurityScreen利用mSecurityModel.getSecurityMode()获取当前的securityMode，传入showSecurityScreen来显示不同锁屏界面。