struct RawEvent {

    nsecs_t when;        //事件发生的时间

    int32_t deviceId;    //产生此事件的设备,比如发送FINISHED_DEVICE_SCAN,不需要填此项

    int32_t type;        //事件类型(如:DEVICE_ADDED,DEVICE_REMOVED,FINISHED_DEVICE_SCAN)

    int32_t scanCode;

    int32_t keyCode;

    int32_t value;

    uint32_t flags;

};  

        // Grab the next input event.

        bool deviceChanged = false;

        while (mPendingEventIndex < mPendingEventCount) {

            const struct epoll_event& eventItem = mPendingEventItems[mPendingEventIndex++];

            if (eventItem.data.u32 == EPOLL_ID_INOTIFY) {

                if (eventItem.events & EPOLLIN) {

                    mPendingINotify = true;

                } else {

                    LOGW("Received unexpected epoll event 0x%08x for INotify.", eventItem.events);

                }

                continue;

            }

            if (eventItem.data.u32 == EPOLL_ID_WAKE) {

                if (eventItem.events & EPOLLIN) {

                    LOGV("awoken after wake()");

                    awoken = true;

                    char buffer[16];

                    ssize_t nRead;

                    do {

                        nRead = read(mWakeReadPipeFd, buffer, sizeof(buffer));

                    } while ((nRead == -1 && errno == EINTR) || nRead == sizeof(buffer));

                } else {

                    LOGW("Received unexpected epoll event 0x%08x for wake read pipe.",

                            eventItem.events);

                }

                continue;

            }

            ssize_t deviceIndex = mDevices.indexOfKey(eventItem.data.u32);

            if (deviceIndex < 0) {

                LOGW("Received unexpected epoll event 0x%08x for unknown device id %d.",

                        eventItem.events, eventItem.data.u32);

                continue;

            }

            Device* device = mDevices.valueAt(deviceIndex);

            if (eventItem.events & EPOLLIN) {

                int32_t readSize = read(device->fd, readBuffer,

                        sizeof(struct input_event) * capacity);

                if (readSize == 0 || (readSize < 0 && errno == ENODEV)) {

                    // Device was removed before INotify noticed.

                    LOGW("could not get event, removed? (fd: %d size: %d bufferSize: %d capacity: %d errno: %d)\n",

                         device->fd, readSize, bufferSize, capacity, errno);

                    deviceChanged = true;

                    closeDeviceLocked(device);

                } else if (readSize < 0) {

                    if (errno != EAGAIN && errno != EINTR) {

                        LOGW("could not get event (errno=%d)", errno);

                    }

                } else if ((readSize % sizeof(struct input_event)) != 0) {

                    LOGE("could not get event (wrong size: %d)", readSize);

                } else {

                    int32_t deviceId = device->id == mBuiltInKeyboardId ? 0 : device->id;

                    size_t count = size_t(readSize) / sizeof(struct input_event);

                    for (size_t i = 0; i < count; i++) {

                        const struct input_event& iev = readBuffer[i];

                        LOGV("%s got: t0=%d, t1=%d, type=%d, code=%d, value=%d",

                                device->path.string(),

                                (int) iev.time.tv_sec, (int) iev.time.tv_usec,

                                iev.type, iev.code, iev.value);

#ifdef HAVE_POSIX_CLOCKS

                        // Use the time specified in the event instead of the current time

                        // so that downstream code can get more accurate estimates of

                        // event dispatch latency from the time the event is enqueued onto

                        // the evdev client buffer.

                        //

                        // The event's timestamp fortuitously uses the same monotonic clock

                        // time base as the rest of Android.  The kernel event device driver

                        // (drivers/input/evdev.c) obtains timestamps using ktime_get_ts().

                        // The systemTime(SYSTEM_TIME_MONOTONIC) function we use everywhere

                        // calls clock_gettime(CLOCK_MONOTONIC) which is implemented as a

                        // system call that also queries ktime_get_ts().

                        event->when = nsecs_t(iev.time.tv_sec) * 1000000000LL

                                + nsecs_t(iev.time.tv_usec) * 1000LL;

                        LOGV("event time %lld, now %lld", event->when, now);

#else

                        event->when = now;

#endif

                        event->deviceId = deviceId;

                        event->type = iev.type;

                        event->scanCode = iev.code;

                        event->value = iev.value;

                        event->keyCode = AKEYCODE_UNKNOWN;

                        event->flags = 0;

                        if (iev.type == EV_KEY && device->keyMap.haveKeyLayout()) {

                            status_t err = device->keyMap.keyLayoutMap->mapKey(iev.code,

                                        &event->keyCode, &event->flags);

                            LOGV("iev.code=%d keyCode=%d flags=0x%08x err=%d\n",

                                    iev.code, event->keyCode, event->flags, err);

                        }

                        event += 1;

                    }

                    capacity -= count;

                    if (capacity == 0) {

                        // The result buffer is full.  Reset the pending event index

                        // so we will try to read the device again on the next iteration.

                        mPendingEventIndex -= 1;

                        break;

                    }

                }

            } else {

                LOGW("Received unexpected epoll event 0x%08x for device %s.",

                        eventItem.events, device->identifier.name.string());

            }

        }

#ifdef HAVE_POSIX_CLOCKS

                        // Use the time specified in the event instead of the current time

                        // so that downstream code can get more accurate estimates of

                        // event dispatch latency from the time the event is enqueued onto

                        // the evdev client buffer.

                        //

                        // The event's timestamp fortuitously uses the same monotonic clock

                        // time base as the rest of Android.  The kernel event device driver

                        // (drivers/input/evdev.c) obtains timestamps using ktime_get_ts().

                        // The systemTime(SYSTEM_TIME_MONOTONIC) function we use everywhere

                        // calls clock_gettime(CLOCK_MONOTONIC) which is implemented as a

                        // system call that also queries ktime_get_ts().

                        event->when = nsecs_t(iev.time.tv_sec) * 1000000000LL

                                + nsecs_t(iev.time.tv_usec) * 1000LL;

                        LOGV("event time %lld, now %lld", event->when, now);

#else

                        event->when = now;

#endif

                        event->deviceId = deviceId;

                        event->type = iev.type;

                        event->scanCode = iev.code;

                        event->value = iev.value;

                        event->keyCode = AKEYCODE_UNKNOWN;

                        event->flags = 0;

                        if (iev.type == EV_KEY && device->keyMap.haveKeyLayout()) {

                            status_t err = device->keyMap.keyLayoutMap->mapKey(iev.code,

                                        &event->keyCode, &event->flags);

                            LOGV("iev.code=%d keyCode=%d flags=0x%08x err=%d\n",

                                    iev.code, event->keyCode, event->flags, err);

                        }

void QueuedInputListener::flush() {

    size_t count = mArgsQueue.size();

    for (size_t i = 0; i < count; i++) {

        NotifyArgs* args = mArgsQueue[i];

        args->notify(mInnerListener);

        delete args;

    }

    mArgsQueue.clear();

}  

for (size_t i = 0; i < mCurrentInputTargets.size(); i++) {

        const InputTarget& inputTarget = mCurrentInputTargets.itemAt(i);  

        ssize_t connectionIndex = getConnectionIndexLocked(inputTarget.inputChannel);

        if (connectionIndex >= 0) {

            sp<Connection> connection = mConnectionsByReceiveFd.valueAt(connectionIndex);

            prepareDispatchCycleLocked(currentTime, connection, eventEntry, & inputTarget,

                    resumeWithAppendedMotionSample);

        } else {

#if DEBUG_FOCUS

            LOGD("Dropping event delivery to target with channel '%s' because it "

                    "is no longer registered with the input dispatcher.",

                    inputTarget.inputChannel->getName().string());

#endif

        }

    }

public class VirtualService

{

    private final static String logString ="VirtualServices";

    /*1.最先执行静态模块方法*/

    static

    {

        /*加载虚拟键盘设备JNI库文件*/

        /*Android.mk：LOCAL_MODULE:= libvirtual_key_jni*/

        Log.i(logString, "load virtual_key_jni.so");

        System.loadLibrary("virtual_key_jni");

        /*加载虚拟鼠标设备JNI库文件*/

        /*Android.mk：LOCAL_MODULE:= libvirtual_mouse_jni*/

        Log.i(logString, "load virtual_mouse_jni.so");

        System.loadLibrary("virtual_mouse_jni");

    }

    /*2.然后执行构造函数方法*/

    public VirtualService()

    {

        /*初始化虚拟键盘设备*/

        Log.i(logString, "init virtual_key Device");

        virtual_key_init();

        /*打开虚拟鼠标设备*/

        /*open('/dev/virtual_dev', O_RDWR)*/

        Log.i(logString, "open virtual_mouse Device");

        virtual_mouse_open();

    }

    /*

     * 提供JNI本地方法的向上接口

     * @arg :按键码，code

     * */

    public String key_write(int arg)

    {

        virtual_key_write(arg);

        Log.i(logString, "KEY" +String.valueOf(arg) +" writed");

        return "KEY " + String.valueOf(arg) + "writed";

    }

    /*初始化虚拟键盘设备*/

    private static native boolean virtual_key_init();

    /* @author:成鹏致远

     * Android层调用virtual_key_write方法，此方法为JNI向上提供的接口

     * virtual_key_write方法被映射到JNI层的virtualkey_write方法

     * JNI层的virtualkey_write方法调用HAL层的write_key

     * HAL层的write_key是一个函数指针，指向HAL层的virtualkey_write方法

     * 在HAL层的virtualkey_write方法中，通过系统调用write进入内核，通知虚拟设备驱动

     * 然后进入到驱动的virtual_dev_write方法，通过input_report_key上报事件，到达linux输入子系统事件处理层，唤醒read

     * 同时Android事件系统的WMS::InputManager->InputReaderThread->loopOnce->getEvent->epoll_wait通过轮询监测到事件发生

     * 然后通过系统调用read从device->fd中读取input_event，即刚才发生的事件

     * 至此就完成了Linux输入子系统与Android输入子系统的完整对接，事件已经传递到Android输入子系统中

     * 将事件保存到getEvent的readBuffer结构中，事件本身为input_event结构体

     * 将input_event填充到RawEvent中

     * 获取到RawEvent之后，调用InputReader->processEventsLocked来处理事件

     * 根据事件设备的class类别，调用对应的消息转换器（InputDevice->InputMapper）如evice->keyMap.keyLayoutMap->mapKey

     * InputMapper把读取的RawEvent转换成特定的事件

     * 将特定的事件放入到各种NotifyArgs（如NotifyMotionArgs）之中，然后加入InputReader::mQueuedListener::mArgsQueue链表中

     * 调用mQueuedListener->flush()把这些队列中的事件发送到Listener

     * 然后调用链表中每个NotifyArgs的notify函数，然后经过一些预处理(比如是否丢弃)

     * 再调用InputDispatcher::enqueueInboundEventLocked把新构造的事件添加到InputDispatcher::mInboundQueue队列中

     * 然后通知此事件到InputManager中的mDispatcher

     * 至此就顺利的从InputReader线程跳转到InputDispatcher线程

     * 然后WMS::InputManager->InputDispatcherThread->dispatchOnce->dispatchOnceInnerLocked->pollOnce被唤醒

     * dispatchOnceInnerLocked从mInboundQueue从中依次取出EventEntry，即刚才添加进来的事件

     * InputDispatcher调用不同的dispatch处理函数来处理此事件

     * 然后就要准备DispatchEntry对象了，即通知Android的UI的原始事件结构

     * 首先调用enqueueDispatchEntryLocked创建DispatchEntry对象，并把它增加到Connection::outboundQueue队列中

     * 接着调用activateConnectionLocked把当前Connection增加到InputDispatcher::mActiveConnections链表中

     * 然后调用InputDispatcher::startDispatchCycleLocked->Connection::inputPublisher.publishMotionEvent,发布事件到ashmem buffer中

     * 至此事件已经放在Android的共享内存了，接着就需要通知DecroWindows(Android第四层Activity)的viewRoot(一个Hander)有新事件产生

     * 调用Connection::inputPublisher.sendDispatchSignal发送一个dispatch信号到InputConsumer通知它有一个新的事件消息到了(通过管道通信)

     * 然后viewRoot的inputChannel接收管道便收到这个事件消息

     * 调用Connection::inputCustomer去共享内存中取得这个事件消息

     * inputCustomer取得这个事件，将这个事件发送到具有当前焦点窗口的viewRoot中

     * viewRoot更新DecroWindows，然后就是我们看到的窗口界面事件响应了

     * */

    /*虚拟键盘写操作方法*/

    /*{ "virtual_key_write", "(I)I",(void*)virtualkey_write }*/

    private static native int virtual_key_write(int arg);

    /*声明虚拟鼠标设备向上提供的JNI本地方法*/

    /*{"virtual_mouse_open", "()I" , (void*)virtual_mouse_open}*/

    private static native int virtual_mouse_open();

    /*{"virtual_mouse_write", "(IIII)I" , (void *)virtual_mouse_write}*/

    public native int virtual_mouse_write(int type, int x, int y, int size);

}