KeyguardServiceWrapper

KeyguardService作为锁屏的服务供系统进程调用。KeyguardService在systemui进程，在system进程KeyguardServiceWrapper是其代理类。系统有相关Keyguard相关的事情要做，都是让KeyguardServiceWrapper去通知KeygaurdService做的。

那么KeyguardServiceWrapper是做到代理KeyguardService呢？
通过追踪代码发现在，当系统SystemServer 的 startOtherServices() 方法中完成各种Service的初始化后，会调用AMS的SystemReady()方法：

    private void startOtherServices(@NonNull TimingsTraceAndSlog t) {
    ....
        mActivityManagerService.systemReady(() -> {
        ....
            mSystemServiceManager.startBootPhase(t, SystemService.PHASE_ACTIVITY_MANAGER_READY);
            ....
            try {
                startSystemUi(context, windowManagerF);  //启动SystemUI进程
            } catch (Throwable e) {
                reportWtf("starting System UI", e);
            }
            ....
        }, t);
    ....
    }

AMS的SystemReady()方法如下。SystemServer 的startSystemUi()方法启动 com.android.internal.R.string.config_systemUIServiceComponent定义的组件，启动SystemUI进程。

public void systemReady(final Runnable goingCallback, @NonNull TimingsTraceAndSlog t) {
        ....
        synchronized(this) {
            if (mSystemReady) {
                if (goingCallback != null) {
                    goingCallback.run();  //执行SystemServer的startOtherServices() 方法传入的线程，见前面的代码
                }
                return;
            }
    ....
        }
    }

SystemServer 的 startSystemUi() 方法：  

private static void startSystemUi(Context context, WindowManagerService windowManager) {
        PackageManagerInternal pm = LocalServices.getService(PackageManagerInternal.class);
        Intent intent = new Intent();
        intent.setComponent(pm.getSystemUiServiceComponent());//指向com.android.systemui/com.android.systemui.SystemUIService服务
        intent.addFlags(Intent.FLAG_DEBUG_TRIAGED_MISSING);
        context.startServiceAsUser(intent, UserHandle.SYSTEM);
        windowManager.onSystemUiStarted();
    }

启动SystemUIService会启动systemui进程，然后执行 WindowManagerService的onSystemUiStarted()方法。方法中mPolicy实际上指向的是PhoneWindowManager

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

再来看WindowManagerService的mPolicy是怎么与PhoneWindowManager关联上的?

原来在SystemServer 的 startOtherServices() 方法中，调用WindowManagerService的main()方法创建WindowManagerService的时候，new 了一个PhoneWindowManager

     private void startOtherServices(@NonNull TimingsTraceAndSlog t) {
     ....
     wm = WindowManagerService.main(context, inputManager, !mFirstBoot, mOnlyCore,
             new PhoneWindowManager()/*WindowManagerService中的mPolicy*/, mActivityManagerService.mActivityTaskManager);
     ....
    }

WindowManagerService的公有方法main()如下，第二个main()方方法构造了WindowManagerService

public static WindowManagerService main(final Context context, final InputManagerService im,
            final boolean showBootMsgs, final boolean onlyCore, WindowManagerPolicy policy,
            ActivityTaskManagerService atm) {
        return main(context, im, showBootMsgs, onlyCore, policy/*指向PhoneWindowManager*/, atm,
                SurfaceControl.Transaction::new, Surface::new, SurfaceControl.Builder::new);
    }
    
 public static WindowManagerService main(final Context context, final InputManagerService im,
            final boolean showBootMsgs, final boolean onlyCore, WindowManagerPolicy policy,
            ActivityTaskManagerService atm, Supplier<SurfaceControl.Transaction> transactionFactory,
            Supplier<Surface> surfaceFactory,
            Function<SurfaceSession, SurfaceControl.Builder> surfaceControlFactory) {
        DisplayThread.getHandler().runWithScissors(() ->
                sInstance = new WindowManagerService(context, im, showBootMsgs, onlyCore, policy/*指向PhoneWindowManager*/,
                        atm, transactionFactory, surfaceFactory, surfaceControlFactory), 0);
        return sInstance;
    }

在WindowManagerService的构造方法中，成员mPolicy最终指向PhoneWindowManager

    private WindowManagerService(Context context, InputManagerService inputManager,
            boolean showBootMsgs, boolean onlyCore, WindowManagerPolicy policy,
            ActivityTaskManagerService atm, Supplier<SurfaceControl.Transaction> transactionFactory,
            Supplier<Surface> surfaceFactory,
            Function<SurfaceSession, SurfaceControl.Builder> surfaceControlFactory) {
                       ....
               mPolicy = policy;/*指向PhoneWindowManager*/
                       ....
    }

接着看PhoneWindowManager的onSystemUiStarted方法，最后会调用KeyguardServiceDelegate的bindService()方法

    public void onSystemUiStarted() {
        bindKeyguard();
    }
    
    private void bindKeyguard() {
        synchronized (mLock) {
            if (mKeyguardBound) {
                return;
            }
            mKeyguardBound = true;
        }
        mKeyguardDelegate.bindService(mContext);
    }

KeyguardServiceDelegate的bindService()方法会真正去bind SystemUI的KeyguardService

    public void bindService(Context context) {
        ....
        //指向com.android.systemui/com.android.systemui.keyguard.KeyguardService
        final ComponentName keyguardComponent = ComponentName.unflattenFromString(
                resources.getString(com.android.internal.R.string.config_keyguardComponent));
        intent.addFlags(Intent.FLAG_DEBUG_TRIAGED_MISSING);
        intent.setComponent(keyguardComponent);

        //bind KeyguardService
        if (!context.bindServiceAsUser(intent, mKeyguardConnection,
                Context.BIND_AUTO_CREATE, mHandler, UserHandle.SYSTEM)) {    
        ....
        }
        ....
    }

服务绑定建立之后， new KeyguardServiceWrapper(),让KeyguardServiceWrapper最为KeygaurdService在System进程的代理。以后系统有相关Keyguard相关的事情要做，那就让KeyguardServiceWrapper去通知KeygaurdService做就OK了。从后面的代码调用全部是mKeyguardService相关的调用就可以看出来。   

private final ServiceConnection mKeyguardConnection = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName name, IBinder service) {
        //KeyguardServiceWrapper最为KeygaurdService在System进程的代理。
        mKeyguardService = new KeyguardServiceWrapper(mContext,
                    IKeyguardService.Stub.asInterface(service), mCallback);
            if (mKeyguardState.systemIsReady) {
                mKeyguardService.onSystemReady();
                if (mKeyguardState.currentUser != UserHandle.USER_NULL) {
                    mKeyguardService.setCurrentUser(mKeyguardState.currentUser);
                }
                if (mKeyguardState.interactiveState == INTERACTIVE_STATE_AWAKE
                        || mKeyguardState.interactiveState == INTERACTIVE_STATE_WAKING) {
                    mKeyguardService.onStartedWakingUp();
                }
                if (mKeyguardState.interactiveState == INTERACTIVE_STATE_AWAKE) {
                    mKeyguardService.onFinishedWakingUp();
                }
                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, false /* animate */);
            }
            if (!mKeyguardState.enabled) {
                mKeyguardService.setKeyguardEnabled(mKeyguardState.enabled);
            }
        }
        ....
    };

从前面的分析可知：
1.KeyguardServiceWrapper是 KeyguardService 在system进程的代理, KeyguardServiceWrapper 其实只是一个空壳子，什么事情都是KeyguardService 去做。
2.在system进程在绑定 KeyguardService之前，会在SystemServer 的 startOtherServices() 方法中先拉起SystemUIService服务，然后再绑定KeyguardService.