public void run() {
 Looper.prepare();
 WindowManagerPolicyThread.set(this, Looper.myLooper());
 ......
 mPolicy.init(mContext, mService, mService, mPM);
 ......
 Looper.loop();
}

public KeyguardViewMediator(Context context, PhoneWindowManager callback,
   LocalPowerManager powerManager) {
  ……
  mUpdateMonitor = new KeyguardUpdateMonitor(context);
  mUpdateMonitor.registerInfoCallback(this);
  mUpdateMonitor.registerSimStateCallback(this);
  mLockPatternUtils = new LockPatternUtils(mContext);
  mKeyguardViewProperties
= new LockPatternKeyguardViewProperties(mLockPatternUtils, mUpdateMonitor);
  mKeyguardViewManager = new KeyguardViewManager(
    context, WindowManagerImpl.getDefault(), this,
    mKeyguardViewProperties, mUpdateMonitor);
  ……
 }

public void systemReady() {
 mPolicy.systemReady();
}

public void onSystemReady() {
 synchronized (this) {
   mSystemReady = true;
   doKeyguardLocked();
 }
}
private void doKeyguardLocked() {
  ......
  // if the keyguard is already showing, don't bother
  if (mKeyguardViewManager.isShowing()) {
   if (DEBUG) Log.d(TAG, "doKeyguard: not showing because it is already showing");
   return;
  }
  .....
  if (DEBUG) Log.d(TAG, "doKeyguard: showing the lock screen");
  showLocked();
}

public synchronized void show() {
  ......
  if (mKeyguardHost == null) {
   if (DEBUG) Log.d(TAG, "keyguard host is null, creating it...");
   mKeyguardHost = new KeyguardViewHost(mContext, mCallback);
   ......
   mViewManager.addView(mKeyguardHost, lp);
  }
  ......
  mViewManager.updateViewLayout(mKeyguardHost, mWindowLayoutParams);
  if (mKeyguardView == null) {
   mKeyguardView = mKeyguardViewProperties.createKeyguardView(mContext, mUpdateMonitor, this);
   ......
   mKeyguardHost.addView(mKeyguardView, lp);
   ......
  }
  ......
}

protected void updateScreen(Mode mode, boolean force) {
   ......
  // Re-create the lock screen if necessary
  if (mode == Mode.LockScreen || mShowLockBeforeUnlock) {
   if (force || mLockScreen == null) {
    recreateLockScreen();
   }
  }
  // Re-create the unlock screen if necessary. This is primarily required to properly handle
  // SIM state changes. This typically happens when this method is called by reset()
  if (mode == Mode.UnlockScreen) {
   final UnlockMode unlockMode = getUnlockMode();
   if (force || mUnlockScreen == null || unlockMode != mUnlockScreenMode) {
    recreateUnlockScreen(unlockMode);
   }
  }
  ......
}

private void setPowerState(int newState, boolean noChangeLights, int reason)
{
  synchronized (mLocks) {
   ……
   if (oldScreenOn != newScreenOn) {
    if (newScreenOn) {
     // When the user presses the power button, we need to always send out the
     // notification that it's going to sleep so the keyguard goes on. But
     // we can't do that until the screen fades out, so we don't show the keyguard
     // too early.
     if (mStillNeedSleepNotification) {
      sendNotificationLocked(false, WindowManagerPolicy.OFF_BECAUSE_OF_USER);
     }
     ……
     if (err == 0) {
      sendNotificationLocked(true, -1);
      // Update the lights *after* taking care of turning the
      // screen on, so we do this after our notifications are
      // enqueued and thus will delay turning on the screen light
      // until the windows are correctly displayed.
      if (stateChanged) {
       updateLightsLocked(newState, 0);
      }
      mPowerState |= SCREEN_ON_BIT;
     }
    } else {
     ……
     if (!mScreenBrightness.animating) {
      err = screenOffFinishedAnimatingLocked(reason);
     }
     ……
    }
   }
   ……
  }
}

private Runnable mNotificationTask = new Runnable()
{
  public void run()
  {
   while (true) {
    ......
    if (value == 1) {
     policy.screenTurningOn(mScreenOnListener);
     ......
    }
    else if (value == 0) {
     policy.screenTurnedOff(why);
     ......
    }
    else {
     // If we're in this case, then this handler is running for a previous
     // paired transaction. mBroadcastWakeLock will already have been released.
     break;
    }
   }
  }
};

/**
* Called to let us know the screen was turned off.
* @param why either {@link WindowManagerPolicy#OFF_BECAUSE_OF_USER},
* {@link WindowManagerPolicy#OFF_BECAUSE_OF_TIMEOUT} or
* {@link WindowManagerPolicy#OFF_BECAUSE_OF_PROX_SENSOR}.
*/
public void onScreenTurnedOff(int why) {
 synchronized (this) {
 ……
 else if (mShowing) { //若是(mShowing)則重置顯示界面，否則重新顯示鎖屏界面
    notifyScreenOffLocked();
    resetStateLocked();
   } else if (why == WindowManagerPolicy.OFF_BECAUSE_OF_TIMEOUT) {
    // if the screen turned off because of timeout, set an alarm
    // to enable it a little bit later (i.e, give the user a chance
    // to turn the screen back on within a certain window without
    // having to unlock the screen)
    ……
    if (timeout <= 0) {
     // Lock now
     mSuppressNextLockSound = true;
     doKeyguardLocked();
    } else {
     // Lock in the future
     long when = SystemClock.elapsedRealtime() + timeout;
     Intent intent = new Intent(DELAYED_KEYGUARD_ACTION);
     intent.putExtra("seq", mDelayedShowingSequence);
     PendingIntent sender = PendingIntent.getBroadcast(mContext,
       0, intent, PendingIntent.FLAG_CANCEL_CURRENT);
     mAlarmManager.set(AlarmManager.ELAPSED_REALTIME_WAKEUP, when,
       sender);
    }
   } else if (why == WindowManagerPolicy.OFF_BECAUSE_OF_PROX_SENSOR) {
    // Do not enable the keyguard if the prox sensor forced the screen off.
   } else { //顯示鎖屏屏幕
    doKeyguardLocked();
   }
  }
}

public void show() {
  if (mMode == Mode.LockScreen) {
   ((KeyguardScreen) mLockScreen).onResume();
  } else {
   ((KeyguardScreen) mUnlockScreen).onResume();
  }
  ......
 }

public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
  // Check if this was the result of hitting the enter key
  if (actionId == EditorInfo.IME_NULL || actionId == EditorInfo.IME_ACTION_DONE
    || actionId == EditorInfo.IME_ACTION_NEXT) {
   verifyPasswordAndUnlock();
   return true;
  }
  return false;
}

public void keyguardDone(boolean authenticated, boolean wakeup) {
 synchronized (this) {
  ……
  Message msg = mHandler.obtainMessage(KEYGUARD_DONE);
  msg.arg1 = wakeup ? 1 : 0;
  mHandler.sendMessage(msg);
  ……
 }
}

public void cleanUp() {
 if (mLockScreen != null) {
  ((KeyguardScreen) mLockScreen).onPause();
  ((KeyguardScreen) mLockScreen).cleanUp();
  this.removeView(mLockScreen);
  mLockScreen = null;
 }
 if (mUnlockScreen != null) {
  ((KeyguardScreen) mUnlockScreen).onPause();
  ((KeyguardScreen) mUnlockScreen).cleanUp();
  this.removeView(mUnlockScreen);
  mUnlockScreen = null;
 }
 ......
}