framework——IMS啟動流程

（1）EventHub

public static void main(String[] args) {
    new SystemServer().run();
}

private void run() {
	try {
		...
		// 創建Looper
		Looper.prepareMainLooper();
		// 加載libandroid_servers.so
		System.loadLibrary("android_servers");
		// 創建系統的 Context：ContextImpl.createSystemContext(new ActivityThread())
		createSystemContext();
		// 創建 SystemServiceManager
		mSystemServiceManager = new SystemServiceManager(mSystemContext);
		LocalServices.addService(SystemServiceManager.class, mSystemServiceManager);
		...
	}
	...
	try {
		//啟動引導服務，ActivityManagerService、ActivityTaskManagerService、PackageManagerService、PowerManagerService、DisplayManagerService 等
		startBootstrapServices(); 
		//啟動核心服務，BatteryService、UsageStatusService 等
		startCoreServices(); 
		//啟動其他服務，InputManagerService、WindowManagerService、CameraService、AlarmManagerService 等
		startOtherServices(); 
		...
	}
	...
	// 開啟訊息回圈
	Looper.loop();
}

private void startOtherServices() {
	...
	WindowManagerService wm = null;
	...
	InputManagerService inputManager = null;
	...
	try {
        ...
        inputManager = new InputManagerService(context);
		...
        //PhoneWindowManager 是 WMP 的實作類
		wm = WindowManagerService.main(context, inputManager, !mFirstBoot, mOnlyCore, new PhoneWindowManager(), mActivityManagerService.mActivityTaskManager);
		ServiceManager.addService(Context.WINDOW_SERVICE, wm, false, DUMP_FLAG_PRIORITY_CRITICAL | DUMP_FLAG_PROTO);
		ServiceManager.addService(Context.INPUT_SERVICE, inputManager, false, DUMP_FLAG_PRIORITY_CRITICAL);
		...
		mActivityManagerService.setWindowManager(wm);
		...
		wm.onInitReady(); //initPolicy
		...
        //wm 的 mInputManagerCallback 屬性在定義時就被初始化
		inputManager.setWindowManagerCallbacks(wm.getInputManagerCallback());
		inputManager.start();
		...
	}
}

IBinder b = ServiceManager.getService(Context.INPUT_SERVICE); 
IInputManager im = IInputManager.Stub.asInterface(b);

public InputManagerService(Context context) {
	this.mContext = context;
	//在 android.display 執行緒中處理訊息
	this.mHandler = new InputManagerHandler(DisplayThread.get().getLooper());
	...
	//mPtr 為 JNI 層 NativeInputManager 物件的地址
	mPtr = nativeInit(this, mContext, mHandler.getLooper().getQueue());
	String doubleTouchGestureEnablePath = context.getResources().getString(R.string.config_doubleTouchGestureEnableFile);
	mDoubleTouchGestureEnableFile = TextUtils.isEmpty(doubleTouchGestureEnablePath) ? null : new File(doubleTouchGestureEnablePath);
	//添加本地服務
	LocalServices.addService(InputManagerInternal.class, new LocalService());
}

public void setWindowManagerCallbacks(WindowManagerCallbacks callbacks) {
	mWindowManagerCallbacks = callbacks;
}

public void start() {
	//啟動 Native 層的 InputReaderThread 和 InputDispatcherThread 執行緒
	nativeStart(mPtr);
	//注冊監聽器
	registerPointerSpeedSettingObserver();
	registerShowTouchesSettingObserver();
	registerAccessibilityLargePointerSettingObserver();

	mContext.registerReceiver(new BroadcastReceiver() {
		@Override
		public void onReceive(Context context, Intent intent) {
			updatePointerSpeedFromSettings();
			updateShowTouchesFromSettings();
			updateAccessibilityLargePointerFromSettings();
		}
	}, new IntentFilter(Intent.ACTION_USER_SWITCHED), null, mHandler);

	updatePointerSpeedFromSettings();
	updateShowTouchesFromSettings();
	updateAccessibilityLargePointerFromSettings();
}

static const JNINativeMethod gInputManagerMethods[] = {
	//Java 層呼叫的 nativeInit 方法對應 JNI 層的 nativeInit 方法
    { "nativeInit",
            "(Lcom/android/server/input/InputManagerService;Landroid/content/Context;Landroid/os/MessageQueue;)J",
            (void*) nativeInit },
	//Java 層呼叫的 nativeStart 方法對應 JNI 層的 nativeStart 方法
    { "nativeStart", "(J)V",
            (void*) nativeStart },
	...
}

#include <inputflinger/InputManager.h>

NativeInputManager::NativeInputManager(jobject contextObj, jobject serviceObj, const sp<Looper>& looper) : 
		mLooper(looper), mInteractive(true) {
    JNIEnv* env = jniEnv();
    mServiceObj = env->NewGlobalRef(serviceObj);
    ...
    mInteractive = true;
	//創建 Native 層 InputManager，2 個 this 分別為：InputReaderPolicyInterface、InputDispatcherPolicyInterface
    mInputManager = new InputManager(this, this);
    defaultServiceManager()->addService(String16("inputflinger"), mInputManager, false);
}

NativeInputManager 實作了 RefBase、InputReaderPolicyInterface、InputDispatcherPolicyInterface、PointerControllerPolicyInterface 4個介面，

InputManager.h 中定義了抽象的 InputManager 類，InputManager.cpp 實作了 InputManager.h 中的抽象方法，

（4）InputManager

/frameworks/native/services/inputflinger/InputManager.h

class InputManager : public InputManagerInterface, public BnInputFlinger {
	...
public:
    InputManager(const sp<InputReaderPolicyInterface>& readerPolicy, const sp<InputDispatcherPolicyInterface>& dispatcherPolicy);
    virtual status_t start();
    ...
    virtual void setInputWindows(const std::vector<InputWindowInfo>& handles, const sp<ISetInputWindowsListener>& setInputWindowsListener);
	virtual void transferTouchFocus(const sp<IBinder>& fromToken, const sp<IBinder>& toToken);
    ...
    virtual void registerInputChannel(const sp<InputChannel>& channel);
private:
    sp<InputReaderInterface> mReader;
    sp<InputReaderThread> mReaderThread;
	sp<InputClassifierInterface> mClassifier;
    sp<InputDispatcherInterface> mDispatcher;
    sp<InputDispatcherThread> mDispatcherThread;
	void initialize();
};

注意：InputManager 繼承了 BnInputFlinger 介面（Binder 跨行程通訊的服務端），

（5）InputManager

/frameworks/native/services/inputflinger/InputManager.cpp

#include "InputManager.h"
#include "InputReaderFactory.h"

InputManager::InputManager(const sp<InputReaderPolicyInterface>& readerPolicy, const sp<InputDispatcherPolicyInterface>& dispatcherPolicy) {
	//創建 InputDispatcher
    mDispatcher = new InputDispatcher(dispatcherPolicy);
    mClassifier = new InputClassifier(mDispatcher);
	//創建 InputReader，createInputReader() 是 InputReaderFactory 類的方法
    mReader = createInputReader(readerPolicy, mClassifier);
    initialize();
}

（6）InputDispatcher

/frameworks/native/services/inputflinger/InputDispatcher.cpp

InputDispatcher::InputDispatcher(const sp<InputDispatcherPolicyInterface>& policy) :
    mPolicy(policy), ... {
	//創建訊息回圈
    mLooper = new Looper(false);
    mReporter = createInputReporter();
    ...
    policy->getDispatcherConfiguration(&mConfig);
}

sp<InputReaderInterface> createInputReader(const sp<InputReaderPolicyInterface>& policy, const sp<InputListenerInterface>& listener) {
    return new InputReader(new EventHub(), policy, listener);
}

注意：此處創建了 EventHub，并注入到 InputReader 中，

void InputManager::initialize() {
    mReaderThread = new InputReaderThread(mReader);
    mDispatcherThread = new InputDispatcherThread(mDispatcher);
}

InputReaderThread 和 InputDispatcherThread 都繼承了 Thread 類，

在 InputManager.h 檔案中，已申明 InputReaderThread 和 InputDispatcherThread 的原始碼不再開源，如下，

/*
 * By design, the InputReaderThread class and InputDispatcherThread class do not share any
 */

（2）start

/frameworks/native/services/inputflinger/InputManager.cpp