編輯:關於Android編程
Android 7.1.1 鎖屏界面啟動流程。前幾天遇到一個低概率復現鎖屏界面不顯示,只顯示狀態欄的問題,跟了下鎖屏界面啟動顯示的流程,在這分享下,也方便以後自己查看。前面簡單介紹了下Zygote啟動流程,Zygote進程啟動後會首先創建一個SystemServer進程,SystemServer進程在調用startOtherServices同時也會調用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中直接調用了PhoneWindowManager裡的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()會根據一個Boolean值bindKeyguardNow來決定是否綁定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(); }
看到這裡,可能會想到如果bindKeyguardNow為false就會不綁定,後面通過繼續跟蹤發現在PhoneWindowManager的systemBooted()裡也會去綁定keyguard service,如果在systemBooted裡綁定了就不在systemReady裡再去綁定,自己測試的時候是在systemBooted綁定的
//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(); }
下面就通過如下的時序圖看看是如何調用到systemBooted的,就不在一步步跟了
通過上面的分析知道,無論是在systemReady或systemBooted,都調用了KeyguardServiceDelegate對象的bindService方法,下面就以這個方法開始,看看鎖屏界面是怎麼顯示出來的,先看看下面的時序圖,再來分步講解
1、先來看看在KeyguardServiceDelegate如何綁定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中調用了bindServiceAsUser綁定指定intent的service,config_keyguardComponent的定義如下
//frameworks/base/core/res/res/values/config.xml當綁定成功後會調用mKeyguardConnection裡的onServiceConnected方法com.android.systemui/com.android.systemui.keyguard.KeyguardService
//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; } }; ... }
今天給大家介紹下Android中滑屏功能的一個基本實現過程以及原理初探,最後給大家重點講解View視圖中scrollTo 與scrollBy這兩個函數的區別 。 
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