Android input 事件分发 -- InputManagerService 初始化

	InputManagerService 作为Android 系统级服务也是在systemServer里面进行初始化的，话不多说先上一张图时序图

frameworks/base/services/java/com/android/server/SystemServer.java

private void startOtherServices() {
	traceBeginAndSlog("StartInputManagerService");
            inputManager = new InputManagerService(context);
            traceEnd();
}

frameworks/base/services/core/java/com/android/server/input/InputManagerService.java

    public InputManagerService(Context context) {
        this.mContext = context;
        this.mHandler = new InputManagerHandler(DisplayThread.get().getLooper());

        mUseDevInputEventForAudioJack =
                context.getResources().getBoolean(R.bool.config_useDevInputEventForAudioJack);
        Slog.i(TAG, "Initializing input manager, mUseDevInputEventForAudioJack="
                + mUseDevInputEventForAudioJack);
          // 这里
        mPtr = nativeInit(this, mContext, mHandler.getLooper().getQueue());

        String doubleTouchGestureEnablePath = context.getResources().getString(
                R.string.config_doubleTouchGestureEnableFile);
        mDoubleTouchGestureEnableFile = TextUtils.isEmpty(doubleTouchGestureEnablePath) ? null :
            new File(doubleTouchGestureEnablePath);

        LocalServices.addService(InputManagerInternal.class, new LocalService());
    }

frameworks/base/services/core/jni/com_android_server_input_InputManagerService.cpp

static jlong nativeInit(JNIEnv* env, jclass /* clazz */,
        jobject serviceObj, jobject contextObj, jobject messageQueueObj) {
    sp<MessageQueue> messageQueue = android_os_MessageQueue_getMessageQueue(env, messageQueueObj);
    if (messageQueue == NULL) {
        jniThrowRuntimeException(env, "MessageQueue is not initialized.");
        return 0;
    }

    // 在NativeInputManager的构造函数里面会new出来InputManager
    NativeInputManager* im = new NativeInputManager(contextObj, serviceObj,
            messageQueue->getLooper());
    im->incStrong(0);
    return reinterpret_cast<jlong>(im);
}

frameworks/base/services/core/jni/com_android_server_input_InputManagerService.cpp

NativeInputManager::NativeInputManager(jobject contextObj,
        jobject serviceObj, const sp<Looper>& looper) :
        mLooper(looper), mInteractive(true) {
    JNIEnv* env = jniEnv();

    mContextObj = env->NewGlobalRef(contextObj);
    mServiceObj = env->NewGlobalRef(serviceObj);

    {
        AutoMutex _l(mLock);
        mLocked.systemUiVisibility = ASYSTEM_UI_VISIBILITY_STATUS_BAR_VISIBLE;
        mLocked.pointerSpeed = 0;
        mLocked.pointerGesturesEnabled = true;
        mLocked.showTouches = false;
        mLocked.pointerCapture = false;
    }
    mInteractive = true;

    // 这里会new出两个比较重要的类，EventHub后面就要用于去访问/dev/input/event*的设备节点
    sp<EventHub> eventHub = new EventHub();
    // InputManager 主要会new出InputDispatcher、InputReader
    mInputManager = new InputManager(eventHub, this, this);
}

frameworks/native/services/inputflinger/InputManager.cpp

InputManager::InputManager(
        const sp<EventHubInterface>& eventHub,
        const sp<InputReaderPolicyInterface>& readerPolicy,
        const sp<InputDispatcherPolicyInterface>& dispatcherPolicy) {
        // 这里分别new出来了InputDispatcher、InputReader，然后将mDispatcher 作为对象传递给了
        // InputReader，InputDispatcher又是间接继承自InputListenerInterface，后面inputReader获取
        // 到input事件就会通知给InputDispatcher进行处理
    mDispatcher = new InputDispatcher(dispatcherPolicy);
    mReader = new InputReader(eventHub, readerPolicy, mDispatcher);
    initialize();
}

InputManager::InputManager(
        const sp<InputReaderInterface>& reader,
        const sp<InputDispatcherInterface>& dispatcher) :
        mReader(reader),
        mDispatcher(dispatcher) {
    initialize();
}

InputManager::~InputManager() {
    stop();
}

// 然后在初始化里面分别new出来InputReadYhread、InputDispatcherThread然后再将InputReader
void InputManager::initialize() {
    mReaderThread = new InputReaderThread(mReader);
    mDispatcherThread = new InputDispatcherThread(mDispatcher);
}

// 在SystemServer里面new 出InputManagerService之后，会间接调用到这个start
status_t InputManager::start() {
    status_t result = mDispatcherThread->run("InputDispatcher", PRIORITY_URGENT_DISPLAY);
    if (result) {
        ALOGE("Could not start InputDispatcher thread due to error %d.", result);
        return result;
    }

    result = mReaderThread->run("InputReader", PRIORITY_URGENT_DISPLAY);
    if (result) {
        ALOGE("Could not start InputReader thread due to error %d.", result);

        mDispatcherThread->requestExit();
        return result;
    }

    return OK;
}

后面的分析的主角就是InputReader、InputReaderThread、InputDispatcher、InputDispatcherThread