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Init------------zygote---------system-server-------------------windosmanager ------------------------------------------------------------ UEventObserver
------------------------------------------------------------ InputDeviceRead
-------------------------------------------------------------InputDispatcher
-------------------------------------------------------------DisplayEventThr
-------------------------------------------------------------ActivityManager

EventHub ：
而事件的傳入是從EventHub開始的，EventHub是事件的抽象結(jié)構(gòu)，維護著系統(tǒng)設(shè)備的運行情況，設(shè)備類型包括Keyboard、 TouchScreen、TraceBall。它在系統(tǒng)啟動的時候會通過open_device方法將系統(tǒng)提供的輸入設(shè)備都增加到這個抽象結(jié)構(gòu)中，并維護一個所有輸入設(shè)備的文件描述符，如果輸入設(shè)備是鍵盤的話還會讀取/system/usr/keylayout/目錄下對應(yīng)鍵盤設(shè)備的映射文件，另外 getEvent方法是對EventHub中的設(shè)備文件描述符使用poll操作等侍驅(qū)動層事件的發(fā)生，如果發(fā)生的事件是鍵盤事件，則調(diào)用Map函數(shù)按照映射文件轉(zhuǎn)換成相應(yīng)的鍵值并將掃描碼和鍵碼返回給KeyInputQueue。
KeyLayoutMap主要是讀取鍵盤映射文件并將鍵盤掃描碼和鍵碼進行轉(zhuǎn)換

frameworks/base/core/jni/server/ com_android_server_KeyInputQueue.cpp
EventHub和KeyinputQueue的JNI接口層

KeyinputQueue：
在線程InputDeviceReader中會根據(jù)事件的類型以及事件值進行判斷處理，從而確定這個事件對應(yīng)的設(shè)備狀態(tài)是否發(fā)生了改變并相應(yīng)的改變對這個設(shè)備的描述結(jié)構(gòu)InputDevice。
getEvent：在給定時間段時看是否有事件發(fā)生，如果有的話返回true否則false。

Windowmanager：
(frameworks/base/services/java/com/android/server/windowmanagerservice.java)
進程Windowmanager會創(chuàng)建一個線程（InputDispatcherThread），在這個線程里從事件隊列中讀取發(fā)生的事件（QueuedEvent ev = mQueue.getEvent（）），并根據(jù)讀取到事件類型的不同分成三類（KEYBOARD、TOUCHSCREEN、TRACKBALL），分別進行處理，例如鍵盤事件會調(diào)用dispatchKey((KeyEvent)ev.event, 0, 0)以將事件通過Binder發(fā)送給具有焦點的窗口應(yīng)用程序，然后調(diào)用 mQueue.recycleEvent(ev)繼續(xù)等侍鍵盤事件的發(fā)生;如果是觸摸屏事件則調(diào)用dispatchPointer(ev, (MotionEvent)ev.event, 0, 0)，這里會根據(jù)事件的種類（UP、DOWN、MOVE、OUT_SIDE等）進行判斷并處理，比如Cancel或?qū)⑹录l(fā)送到具有權(quán)限的指定的窗口中去;

Android 輸入事件流程

EventHub

EventHub對輸入設(shè)備進行了封裝。輸入設(shè)備驅(qū)動程序?qū)τ脩艨臻g應(yīng)用程序提供一些設(shè)備文件，這些設(shè)備文件放在/dev/input里面。

EventHub掃描/dev/input下所有設(shè)備文件，并打開它們。

C代碼

bool EventHub::openPlatformInput( void )
{
...
mFDCount=1;
mFDs=(pollfd*)calloc(1, sizeof (mFDs[0]));
mDevices=(device_t**)calloc(1, sizeof (mDevices[0]));
mFDs[0].events=POLLIN;
mDevices[0]=NULL;
res=scan_dir(device_path);
...
return true ;
}

    bool EventHub::openPlatformInput(void)
{
...
    mFDCount = 1;
    mFDs = (pollfd *)calloc(1, sizeof(mFDs[0]));
    mDevices = (device_t **)calloc(1, sizeof(mDevices[0]));
    mFDs[0].events = POLLIN;
    mDevices[0] = NULL;

    res = scan_dir(device_path);
...
    return true;
}

EventHub對外提供了一個函數(shù)用于從輸入設(shè)備文件中讀取數(shù)據(jù)。

C代碼

bool EventHub::getEvent(int32_t*outDeviceId,int32_t*outType,
int32_t*outScancode,int32_t*outKeycode,uint32_t*outFlags,
int32_t*outValue,nsecs_t*outWhen)
{
...
while (1){
//First,reportanydevicesthathadlastbeenadded/removed.
if (mClosingDevices!=NULL){
device_t*device=mClosingDevices;
LOGV( "Reportingdeviceclosed:id=0x%x,name=%s/n" ,
device->id,device->path.string());
mClosingDevices=device->next;
*outDeviceId=device->id;
if (*outDeviceId==mFirstKeyboardId)*outDeviceId=0;
*outType=DEVICE_REMOVED;
delete device;
return true ;
}
if (mOpeningDevices!=NULL){
device_t*device=mOpeningDevices;
LOGV( "Reportingdeviceopened:id=0x%x,name=%s/n" ,
device->id,device->path.string());
mOpeningDevices=device->next;
*outDeviceId=device->id;
if (*outDeviceId==mFirstKeyboardId)*outDeviceId=0;
*outType=DEVICE_ADDED;
return true ;
}
release_wake_lock(WAKE_LOCK_ID);
pollres=poll(mFDs,mFDCount,-1);
acquire_wake_lock(PARTIAL_WAKE_LOCK,WAKE_LOCK_ID);
if (pollres<=0){
if (errno!=EINTR){
LOGW( "selectfailed(errno=%d)/n" ,errno);
usleep(100000);
}
continue ;
}
for (i=1;i<mFDCount;i++){
if (mFDs[i].revents){
LOGV( "reventsfor%d=0x%08x" ,i,mFDs[i].revents);
if (mFDs[i].revents&POLLIN){
res=read(mFDs[i].fd,&iev, sizeof (iev));
if (res== sizeof (iev)){
LOGV( "%sgot:t0=%d,t1=%d,type=%d,code=%d,v=%d" ,
mDevices[i]->path.string(),
( int )iev.time.tv_sec,( int )iev.time.tv_usec,
iev.type,iev.code,iev.value);
*outDeviceId=mDevices[i]->id;
if (*outDeviceId==mFirstKeyboardId)*outDeviceId=0;
*outType=iev.type;
*outScancode=iev.code;
if (iev.type==EV_KEY){
err=mDevices[i]->layoutMap->map(iev.code,outKeycode,outFlags);
LOGV( "iev.code=%doutKeycode=%doutFlags=0x%08xerr=%d/n" ,
iev.code,*outKeycode,*outFlags,err);
if (err!=0){
*outKeycode=0;
*outFlags=0;
}
} else {
*outKeycode=iev.code;
}
*outValue=iev.value;
*outWhen=s2ns(iev.time.tv_sec)+us2ns(iev.time.tv_usec);
return true ;
} else {
if (res<0){
LOGW( "couldnotgetevent(errno=%d)" ,errno);
} else {
LOGE( "couldnotgetevent(wrongsize:%d)" ,res);
}
continue ;
}
}
}
}
...
}

    bool EventHub::getEvent(int32_t* outDeviceId, int32_t* outType,
        int32_t* outScancode, int32_t* outKeycode, uint32_t *outFlags,
        int32_t* outValue, nsecs_t* outWhen)
{
	...
    while(1) {

        // First, report any devices that had last been added/removed.
        if (mClosingDevices != NULL) {
            device_t* device = mClosingDevices;
            LOGV("Reporting device closed: id=0x%x, name=%s/n",
                 device->id, device->path.string());
            mClosingDevices = device->next;
            *outDeviceId = device->id;
            if (*outDeviceId == mFirstKeyboardId) *outDeviceId = 0;
            *outType = DEVICE_REMOVED;
            delete device;
            return true;
        }
        if (mOpeningDevices != NULL) {
            device_t* device = mOpeningDevices;
            LOGV("Reporting device opened: id=0x%x, name=%s/n",
                 device->id, device->path.string());
            mOpeningDevices = device->next;
            *outDeviceId = device->id;
            if (*outDeviceId == mFirstKeyboardId) *outDeviceId = 0;
            *outType = DEVICE_ADDED;
            return true;
        }

        release_wake_lock(WAKE_LOCK_ID);

        pollres = poll(mFDs, mFDCount, -1);

        acquire_wake_lock(PARTIAL_WAKE_LOCK, WAKE_LOCK_ID);

        if (pollres <= 0) {
            if (errno != EINTR) {
                LOGW("select failed (errno=%d)/n", errno);
                usleep(100000);
            }
            continue;
        }

        for(i = 1; i < mFDCount; i++) {
            if(mFDs[i].revents) {
                LOGV("revents for %d = 0x%08x", i, mFDs[i].revents);
                if(mFDs[i].revents & POLLIN) {
                    res = read(mFDs[i].fd, &iev, sizeof(iev));
                    if (res == sizeof(iev)) {
                        LOGV("%s got: t0=%d, t1=%d, type=%d, code=%d, v=%d",
                             mDevices[i]->path.string(),
                             (int) iev.time.tv_sec, (int) iev.time.tv_usec,
                             iev.type, iev.code, iev.value);
                        *outDeviceId = mDevices[i]->id;
                        if (*outDeviceId == mFirstKeyboardId) *outDeviceId = 0;
                        *outType = iev.type;
                        *outScancode = iev.code;
                        if (iev.type == EV_KEY) {
                            err = mDevices[i]->layoutMap->map(iev.code, outKeycode, outFlags);
                            LOGV("iev.code=%d outKeycode=%d outFlags=0x%08x err=%d/n",
                                iev.code, *outKeycode, *outFlags, err);
                            if (err != 0) {
                                *outKeycode = 0;
                                *outFlags = 0;
                            }
                        } else {
                            *outKeycode = iev.code;
                        }
                        *outValue = iev.value;
                        *outWhen = s2ns(iev.time.tv_sec) + us2ns(iev.time.tv_usec);
                        return true;
                    } else {
                        if (res<0) {
                            LOGW("could not get event (errno=%d)", errno);
                        } else {
                            LOGE("could not get event (wrong size: %d)", res);
                        }
                        continue;
                    }
                }
            }
        }
	...
}

對于按鍵事件，調(diào)用mDevices[i]->layoutMap->map進行映射。映射實際是由 KeyLayoutMap::map完成的，KeyLayoutMap類里讀取配置文件qwerty.kl，由配置文件 qwerty.kl 決定鍵值的映射關(guān)系。你可以通過修改./development/emulator/keymaps/qwerty.kl來改變鍵值的映射關(guān)系。
JNI 函數(shù)

在 frameworks/base/services/jni/com_android_server_KeyInputQueue.cpp文件中，向 JAVA提供了函數(shù)android_server_KeyInputQueue_readEvent，用于讀取輸入設(shè)備事件。

C代碼

static jboolean
android_server_KeyInputQueue_readEvent(JNIEnv*env,jobjectclazz,
jobjectevent)
{
gLock.lock();
sphub=gHub;
if (hub==NULL){
hub= new EventHub;
gHub=hub;
}
gLock.unlock();
int32_tdeviceId;
int32_ttype;
int32_tscancode,keycode;
uint32_tflags;
int32_tvalue;
nsecs_twhen;
bool res=hub->getEvent(&deviceId,&type,&scancode,&keycode,
&flags,&value,&when);
env->SetIntField(event,gInputOffsets.mDeviceId,(jint)deviceId);
env->SetIntField(event,gInputOffsets.mType,(jint)type);
env->SetIntField(event,gInputOffsets.mScancode,(jint)scancode);
env->SetIntField(event,gInputOffsets.mKeycode,(jint)keycode);
env->SetIntField(event,gInputOffsets.mFlags,(jint)flags);
env->SetIntField(event,gInputOffsets.mValue,value);
env->SetLongField(event,gInputOffsets.mWhen,
(jlong)(nanoseconds_to_milliseconds(when)));
return res;
}

    static jboolean
android_server_KeyInputQueue_readEvent(JNIEnv* env, jobject clazz,
                                          jobject event)
{
    gLock.lock();
    sp hub = gHub;
    if (hub == NULL) {
        hub = new EventHub;
        gHub = hub;
    }
    gLock.unlock();

    int32_t deviceId;
    int32_t type;
    int32_t scancode, keycode;
    uint32_t flags;
    int32_t value;
    nsecs_t when;
    bool res = hub->getEvent(&deviceId, &type, &scancode, &keycode,
            &flags, &value, &when);

    env->SetIntField(event, gInputOffsets.mDeviceId, (jint)deviceId);
    env->SetIntField(event, gInputOffsets.mType, (jint)type);
    env->SetIntField(event, gInputOffsets.mScancode, (jint)scancode);
    env->SetIntField(event, gInputOffsets.mKeycode, (jint)keycode);
    env->SetIntField(event, gInputOffsets.mFlags, (jint)flags);
    env->SetIntField(event, gInputOffsets.mValue, value);
    env->SetLongField(event, gInputOffsets.mWhen,
                        (jlong)(nanoseconds_to_milliseconds(when)));

    return res;
}

readEvent調(diào)用hub->getEvent讀了取事件，然后轉(zhuǎn)換成JAVA的結(jié)構(gòu)。
事件中轉(zhuǎn)線程

在frameworks/base/services/java/com/android/server/KeyInputQueue.java 里創(chuàng)建了一個線程，它循環(huán)的讀取事件，然后把事件放入事件隊列里。

Java代碼

ThreadmThread= new Thread( "InputDeviceReader" ){
public void run(){
android.os.Process.setThreadPriority(
android.os.Process.THREAD_PRIORITY_URGENT_DISPLAY);
try {
RawInputEventev= new RawInputEvent();
while ( true ){
InputDevicedi;
readEvent(ev);
send=preprocessEvent(di,ev);
addLocked(di,curTime,ev.flags,...,me);
}
}
};

    Thread mThread = new Thread("InputDeviceReader") {
        public void run() {
            android.os.Process.setThreadPriority(
                    android.os.Process.THREAD_PRIORITY_URGENT_DISPLAY);

            try {
                RawInputEvent ev = new RawInputEvent();
                while (true) {
                    InputDevice di;

                    readEvent(ev);

                    send = preprocessEvent(di, ev);
                    addLocked(di, curTime, ev.flags, ..., me);
                }
        }
    };

輸入事件分發(fā)線程

在frameworks/base/services/java/com/android/server/WindowManagerService.java里創(chuàng)建了一個輸入事件分發(fā)線程，它負責把事件分發(fā)到相應(yīng)的窗口上去。

Java代碼

mQueue.getEvent
dispatchKey/dispatchPointer/dispatchTrackball

    mQueue.getEvent
dispatchKey/dispatchPointer/dispatchTrackball

按鍵,觸摸屏流程分析

按鍵觸摸屏流程分析:
WindowManagerService類的構(gòu)造函數(shù)
WindowManagerService()
mQueue = new KeyQ();
因為 WindowManagerService.java (frameworks/base/services/java/com/android/server)中有：
private class KeyQ extends KeyInputQueue
KeyQ 是抽象類 KeyInputQueue 的實現(xiàn)，所以 new KeyQ類的時候?qū)嶋H上在 KeyInputQueue 類中創(chuàng)建了
一個線程 InputDeviceReader 專門用來沖設(shè)備讀取按鍵事件，代碼：
Thread mThread = new Thread("InputDeviceReader") {
public void run()
{
在循環(huán)中調(diào)用：readEvent(ev);
...
send = preprocessEvent(di, ev);
實際調(diào)用的是 KeyQ 類的 preprocessEvent 函數(shù)
...
int keycode = rotateKeyCodeLocked(ev.keycode);
int[] map = mKeyRotationMap;
for (int i=0; i<N; i+=2)
{
if (map[i] == keyCode)
return map[i+1];
} //
addLocked(di, curTime, ev.flags,RawInputEvent.CLASS_KEYBOARD,newKeyEvent(di, di.mDownTime, curTime, down,keycode, 0, scancode,...));
QueuedEvent ev = obtainLocked(device, when, flags, classType, event);
}
}

readEvent() 實際上調(diào)用的是 com_android_server_KeyInputQueue.cpp (frameworks/base/services/jni)中的：
static jboolean android_server_KeyInputQueue_readEvent(JNIEnv* env, jobject clazz,jobject event)
bool res = hub->getEvent(&deviceId, &type, &scancode, &keycode,&flags, &value, &when);
調(diào)用的是 EventHub.cpp (frameworks/base/libs/ui)中的：
bool EventHub::getEvent(int32_t* outDeviceId, int32_t* outType,
int32_t* outScancode, int32_t* outKeycode, uint32_t *outFlags,
int32_t* outValue, nsecs_t* outWhen)
在函數(shù)中調(diào)用了讀設(shè)備操作：res = read(mFDs[i].fd, &iev, sizeof(iev));

在構(gòu)造函數(shù) WindowManagerService()調(diào)用 new KeyQ() 以后接著調(diào)用了：
mInputThread = new InputDispatcherThread();
...
mInputThread.start();
來啟動一個線程 InputDispatcherThread
run()
process();
QueuedEvent ev = mQueue.getEvent(...)
因為WindowManagerService類中： final KeyQ mQueue;
所以實際上 InputDispatcherThread 線程實際上從 KeyQ 的事件隊列中讀取按鍵事件。
switch (ev.classType)
case RawInputEvent.CLASS_KEYBOARD:
...
dispatchKey((KeyEvent)ev.event, 0, 0);
mQueue.recycleEvent(ev);
break;
case RawInputEvent.CLASS_TOUCHSCREEN:
//Log.i(TAG, "Read next event " + ev);
dispatchPointer(ev, (MotionEvent)ev.event, 0, 0);
break;

===============================================================

KeyInputQueue.java (frameworks/base/services/java/com/android/server):
的線程 Thread mThread = new Thread("InputDeviceReader") 本地調(diào)用：
readEvent(ev);讀取按鍵。readEvent 調(diào)用的是文件：
com_android_server_KeyInputQueue.cpp (frameworks/base/services/jni)中的函數(shù)：
static jboolean android_server_KeyInputQueue_readEvent(JNIEnv* env, jobject clazz,
jobject event)
android_server_KeyInputQueue_readEvent中有：
hub = new EventHub;
bool res = hub->getEvent(&deviceId, &type, &scancode, &keycode,
&flags, &value, &when);

hub->getEvent 調(diào)用的是
EventHub.cpp (frameworks/base/libs/ui) 文件中的函數(shù)：
bool EventHub::getEvent(int32_t* outDeviceId, int32_t* outType,
int32_t* outScancode, int32_t* outKeycode, uint32_t *outFlags,
int32_t* outValue, nsecs_t* outWhen)
讀取按鍵。

class RefBase::weakref_impl : public RefBase::weakref_type

在系統(tǒng)啟動后，android 會通過
static const char *device_path = "/dev/input";
bool EventHub::openPlatformInput(void)
res = scan_dir(device_path);

通過下面的函數(shù)打開設(shè)備。
int EventHub::open_device(const char *deviceName)
{
...
fd = open(deviceName, O_RDWR);
...
mFDs[mFDCount].fd = fd;
mFDs[mFDCount].events = POLLIN;
...
ioctl(mFDs[mFDCount].fd, EVIOCGNAME(sizeof(devname)-1), devname);
...
const char* root = getenv("ANDROID_ROOT");
snprintf(keylayoutFilename, sizeof(keylayoutFilename),
"%s/usr/keylayout/%s.kl", root, tmpfn);
...
device->layoutMap->load(keylayoutFilename);
...
}
打開設(shè)備的時候，如果 device->classes&CLASS_KEYBOARD 不等于 0 表明是鍵盤。
常用輸入設(shè)備的定義有：
enum {
CLASS_KEYBOARD = 0x00000001, //鍵盤
CLASS_ALPHAKEY = 0x00000002, //
CLASS_TOUCHSCREEN = 0x00000004, //觸摸屏
CLASS_TRACKBALL = 0x00000008 //軌跡球
};
打開鍵盤設(shè)備的時候通過上面的 ioctl 獲得設(shè)備名稱，命令字 EVIOCGNAME 的定義在文件：
kernel/include/linux/input.h 中。
#define EVIOCGNAME(len) _IOC(_IOC_READ, 'E', 0x06, len) /* get device name */
在內(nèi)核鍵盤驅(qū)動文件 drivers/input/keyboard/pxa27x_keypad.c 中定義了設(shè)備名稱：pxa27x-keypad
static struct platform_driver pxa27x_keypad_driver = {
.probe = pxa27x_keypad_probe,
.remove = __devexit_p(pxa27x_keypad_remove),
.suspend = pxa27x_keypad_suspend,
.resume = pxa27x_keypad_resume,
.driver = {
.name = "pxa27x-keypad",
.owner = THIS_MODULE,
},
};
ANDROID_ROOT 為環(huán)境變量，在android的命令模式下通過 printenv 可以知道它為： system
所以 keylayoutFilename 為：/system/usr/keylayout/pxa27x-keypad.kl
pxa27x-keypad.kl 定義了按鍵映射，具體內(nèi)容如下：
－－－－－－－－－－－－－－－－－－－－－－
# NUMERIC KEYS 3x4
key 2 1
key 3 2
key 4 3
key 5 4
key 6 5
key 7 6
key 8 7
key 9 8
key 10 9
key 11 0
key 83 POUND
key 55 STAR

# FUNCTIONAL KEYS
key 231 MENU WAKE_DROPPED
key 192 BACK WAKE_DROPPED
key 193 HOME WAKE
key 107 DEL WAKE
key 102 CALL WAKE_DROPPED
key 158 ENDCALL WAKE_DROPPED
key 28 DPAD_CENTER WAKE
key 115 VOLUME_UP
key 114 VOLUME_DOWN
－－－－－－－－－－－－－－－－－－－－－－
如果沒有定義鍵盤映射文件，那么默認使用系統(tǒng)的 /system/usr/keylayout/qwerty.kl
可以修改 /system/usr/keylayout/qwerty.kl 文件改變Android公司的按鍵映射。

device->layoutMap->load(keylayoutFilename) 調(diào)用的是文件：
KeyLayoutMap.cpp (frameworks/base/libs/ui)中的函數(shù)：
status_t KeyLayoutMap::load(const char* filename)通過解析 pxa27x-keypad.kl
把按鍵的映射關(guān)系保存在：KeyedVector<int32_t,Key> m_keys; 中。
當獲得按鍵事件以后調(diào)用：
status_t KeyLayoutMap::map(int32_t scancode, int32_t *keycode, uint32_t *flags)
由映射關(guān)系 KeyedVector<int32_t,Key> m_keys 把掃描碼轉(zhuǎn)換成andorid上層可以識別的按鍵。

Android事件處理流程

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