第七篇 窗口系统机制之KEYGUARD机制
ANDROID的KEYGUARD相关类提供了屏幕锁屏等相关功能，虽然功能简单，但是相关的逻辑还是挺复杂的，要处理屏幕处于不同状态的情况，要监控各种事件（时间，电池，Sim状态，电话状态），因此GOOGLE还是对屏幕功能进行了细致的设计，架构上采用了中介模式、MVC模式等设计模式。系统类图如下：
PhoneWindowManager、PowerManager、KeyguardViewMediator、KeyguardUpdateMonitor、KeyguardViewManager、KeyguardViewHost、LockPatternKeyguardView、KeyguardScreen相关类之间构成中介模式，KeyguardViewMediator对象处于模式的核心，起到中介者的角色，其它对象都通过KeyguardViewMediator对象相互交互。
KeyguardViewMediator对象是PhoneWindowManager成员，因此PhoneWindowManage可以直接访问KeyguardViewMediator对象。KeyguardViewMediator也通过PowerManager服务创建了三个不计数WakeLock锁实现与PowerManager服务的通讯，达到锁屏操作时电源状态管理的目的（mWakeLock锁用于保证在 keyguard显示时能够显示一段时间后屏幕才能睡眠；mShowKeyguardWakeLock用于在 keyguard显示要打开时能够保持设备唤醒；mWakeAndHandOff由PhoneWindowManager截获事件进行触发，用于在用户按键或鼠标移动时唤醒设备便于对keyguard进行操作）。KeyguardUpdateMonitor、KeyguardViewManager对象作为KeyguardViewMediator对象的成员又都是由KeyguardViewMediator实例化的，KeyguardViewMediator可以直接操作KeyguardUpdateMonitor、KeyguardViewManager对象。
而KeyguardViewHost、LockPatternKeyguardView作为视图对象通过调用KeyguardViewManager对象的show函数创建并作为视图添加到窗口上, KeyguardViewHost作为窗口得主视图, LockPatternKeyguardView是KeyguardViewHost的子视图。KeyguardScreen类是各类锁屏、解锁屏幕的接口，各类锁屏、解锁屏幕都是KeyguardScreen类的视图实现类，在调用LockPatternKeyguardView的updateScreen函数时根据不同的模式作为LockPatternKeyguardView的子视图添加到LockPatternKeyguardView视图上显示。
KeyguardUpdateMonitor、KeyguardViewHost、LockPatternKeyguardView、KeyguardScreen接口的对象都通过回调与KeyguardViewMediator反向调用。
KeyguardUpdateMonitor 类实现时间，电池，Sim状态，电话状态的监视，KeyguardViewMediator类是KeyguardUpdateMonitor类内部回调接口InfoCallback、SimStateCallbac的实现类，因此KeyguardViewMediator对象可以作为KeyguardUpdateMonitor对象的回调对象，通过KeyguardUpdateMonitor的registerInfoCallback和registerSimStateCallback函数把KeyguardViewMediator对象添加到KeyguardUpdateMonitor对象的回调对象列表中，当KeyguardViewMediator对象检测到时间，电池，Sim状态，电话状态变化时通过回调调用KeyguardViewMediator对象的相关接口。
KeyguardViewMediator类也是KeyguardViewCallback接口的实现，因此在KeyguardViewManager实例化时KeyguardViewMediator对象也作为KeyguardViewCallback类型的参数传进KeyguardViewManager作为KeyguardViewManager的内部成员mCallback。然后mCallback又作为参数在KeyguardViewHost对象实例化时传进去作为KeyguardViewHost对象的成员，并通过LockPatternKeyguardView的函数setCallback设置LockPatternKeyguardView对象的回调对象，因此KeyguardViewHost、LockPatternKeyguardView都可以通过KeyguardViewCallback类型的回调对象与KeyguardViewMediator对象通讯。
LockPatternKeyguardView对象创建了六个实现了KeyguardScreen接口的各个锁屏、解锁屏幕对象，LockScreen用于显示屏幕加锁状态，另外根据不同的unlockMode模式创建了不同的解锁屏幕：PatternUnlockScreen实现图案解锁模式，SimPukUnlockScreen屏幕实现SIM PUK码解锁模式，SimUnlockScreen实现 Sim PIN码解锁模式，AccountUnlockScreen实现 GOOGLE帐户解锁，PasswordUnlockScreen实现口令解锁模式。
每个锁屏、解锁屏幕对象在创建时都传进去一个实现了KeyguardScreenCallback接口的回调对象mKeyguardScreenCallback（LockPatternKeyguardView的一个成员），KeyguardScreenCallback接口派生自KeyguardViewCallback接口。在mKeyguardScreenCallback回调对象中实现了KeyguardViewCallback类型的回调对象mCallback的包装（装饰模式的采用），因此各个锁屏、解锁屏幕对象可以通过KeyguardScreenCallback接口与KeyguardViewMediator对象通讯。
另外KeyguardUpdateMonitor、KeyguardViewManager、LockPatternKeyguardView、KeyguardScreen类还构成了MVC模式。KeyguardUpdateMonitor实现了MVC模式中的模式角色，用来提供模式状态数据。KeyguardViewManager担当MVC模式中的控制器角色，通过KeyguardViewManager生成视图，生成和控制视图的表现。LockPatternKeyguardView、KeyguardScreen接口类对象担当视图角色，模式可以直接向视图传送状态（通过把LockPatternKeyguardView和锁屏、解锁屏幕的内部对象作为回调对象登记到KeyguardUpdateMonitor对象的回调对象列表中），视图也可以直接读取KeyguardUpdateMonitor模式的状态数据，因此LockPatternKeyguardView、KeyguardScree类对象视图中都有一个KeyguardUpdateMonitor对象的引用。
LockPatternKeyguardView对象由LockPatternKeyguardViewProperties对象采用了工厂方法进行实例化。
各个对象的实例化代码片断：
PhoneWindowManager对象WindowManagerService.java中实例化，并在WindowManagerService的PolicyThread线程运行时初始化。
final WindowManagerPolicy mPolicy = PolicyManager.makeNewWindowManager();
public PolicyThread(WindowManagerPolicy policy,
WindowManagerService service, Context context,
PowerManagerService pm) {
super("WindowManagerPolicy");
mPolicy = policy;
mService = service;
mContext = context;
mPM = pm;
}
public void run() {
Looper.prepare();
mPolicy.init(mContext, mService, mService, mPM);
synchronized (this) {
}
Looper.loop();
}
}
final WindowManagerPolicy mPolicy = PolicyManager.makeNewWindowManager(); public PolicyThread(WindowManagerPolicy policy, WindowManagerService service, Context context, PowerManagerService pm) { super("WindowManagerPolicy"); mPolicy = policy; mService = service; mContext = context; mPM = pm; } public void run() { Looper.prepare(); mPolicy.init(mContext, mService, mService, mPM); synchronized (this) { } Looper.loop(); } }
在PhoneWindowManager对象init函数调用时实例化KeyguardMediator对象
public void init(Context context, IWindowManager windowManager, WindowManagerFuncs windowManagerFuncs, LocalPowerManager powerManager) { … mKeyguardMediator = new KeyguardViewMediator(context, this, powerManager); }
KeyguardViewMediator构造函数中实例化PowerManager的三个锁及KeyguardUpdateMonitor、LockPatternKeyguardViewProperties、KeyguardViewManager对象。
public KeyguardViewMediator(Context context, PhoneWindowManager callback, LocalPowerManager powerManager) { mPM = (PowerManager) context.getSystemService(Context.POWER_SERVICE); mWakeLock = mPM.newWakeLock(PowerManager.FULL_WAKE_LOCK | PowerManager.ACQUIRE_CAUSES_WAKEUP, "keyguard"); mWakeLock.setReferenceCounted(false); mShowKeyguardWakeLock=mPM.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "show keyguard"); mShowKeyguardWakeLock.setReferenceCounted(false); mWakeAndHandOff = mPM.newWakeLock( PowerManager.PARTIAL_WAKE_LOCK, "keyguardWakeAndHandOff"); mWakeAndHandOff.setReferenceCounted(false); mUpdateMonitor = new KeyguardUpdateMonitor(context); mUpdateMonitor.registerInfoCallback(this); mUpdateMonitor.registerSimStateCallback(this);、 mKeyguardViewProperties=new LockPatternKeyguardViewProperties(mLockPatternUtils, mUpdateMonitor); mKeyguardViewManager = new KeyguardViewManager( context, WindowManagerImpl.getDefault(), this, mKeyguardViewProperties, mUpdateMonitor); }
在KeyguardViewManager的show中实例化KeyguardViewHost、LockPatternKeyguardView对象。
public synchronized void show() { if (mKeyguardHost == null) { mKeyguardHost = new KeyguardViewHost(mContext, mCallback); WindowManager.LayoutParams lp = new WindowManager.LayoutParams( stretch, stretch, WindowManager.LayoutParams.TYPE_KEYGUARD, flags, PixelFormat.TRANSLUCENT); mViewManager.addView(mKeyguardHost, lp); } if (mKeyguardView == null) { mKeyguardView = mKeyguardViewProperties.createKeyguardView(mContext, mUpdateMonitor, this); mKeyguardView.setCallback(mCallback); final ViewGroup.LayoutParams lp = new FrameLayout.LayoutParams( ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT); mKeyguardHost.addView(mKeyguardView, lp); }
在LockPatternKeyguardView的createLockScreen和createUnlockScreenFor函数中创建加锁和解锁屏幕。
View createLockScreen() {
View lockView = new LockScreen(
mContext,
mConfiguration,
mLockPatternUtils,
mUpdateMonitor,
mKeyguardScreenCallback);
return lockView;
}
View createUnlockScreenFor(UnlockMode unlockMode) {
if (unlockMode == UnlockMode.Pattern) {
PatternUnlockScreen view = new PatternUnlockScreen(
mContext,
mConfiguration,
mLockPatternUtils,
mUpdateMonitor,
mKeyguardScreenCallback,
mUpdateMonitor.getFailedAttempts());
} else if (unlockMode == UnlockMode.SimPuk) {
unlockView = new SimPukUnlockScreen(
mContext,
mConfiguration,
mUpdateMonitor,
mKeyguardScreenCallback,
mLockPatternUtils);
} else if (unlockMode == UnlockMode.SimPin) {
unlockView = new SimUnlockScreen(
mContext,
mConfiguration,
mUpdateMonitor,
mKeyguardScreenCallback,
mLockPatternUtils);
} else if (unlockMode == UnlockMode.Account) {
unlockView = new AccountUnlockScreen(
mContext,
mConfiguration,
mUpdateMonitor,
mKeyguardScreenCallback,
mLockPatternUtils);
} else if (unlockMode == UnlockMode.Password) {
unlockView = new PasswordUnlockScreen(
mContext,
mConfiguration,
mLockPatternUtils,
mUpdateMonitor,
mKeyguardScreenCallback);
}
return unlockView;
}
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