Android 事件处理流程

核心提示：一个线程 InputDeviceReader 专门用来冲设备读取按键事件，代码：Thread mThread = new Thread("InputDeviceReader") {public void run(){在循环中调用：readEvent(ev);...send = preprocessE

一个线程 InputDeviceReader 专门用来冲设备读取按键事件，代码：

Thread mThread = new Thread("InputDeviceReader") {

public void run()

{

在循环中调用：readEvent(ev);

...

send = preprocessEvent(di, ev);

实际调用的是 KeyQ 类的 preprocessEvent 函数

...

int keycode = rotateKeyCodeLocked(ev.keycode);

int[] map = mKeyRotationMap;

for (int i=0; i

{

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() 实际上调用的是 com_android_server_KeyInputQueue.cpp (frameworksaseservicesjni)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);

调用的是 EventHub.cpp (frameworksaselibsui)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)

在函数中调用了读设备操作：res = read(mFDs[i].fd, &iev, sizeof(iev));

在构造函数 WindowManagerService()调用 new KeyQ() 以后接着调用了：

mInputThread = new InputDispatcherThread();

...

mInputThread.start();

来启动一个线程 InputDispatcherThread

run()

process();

QueuedEvent ev = mQueue.getEvent(...)

因为WindowManagerService类中： final KeyQ mQueue;

所以实际上 InputDispatcherThread 线程实际上从 KeyQ 的事件队列中读取按键事件。