按键事件

对于按键事件，调用mDevices->layoutMap->map进行映射。映射实际是由 KeyLayoutMap::map完成的，KeyLayoutMap类里读取配置文件qwerty.kl，由配置 文件 qwerty.kl 决定键值的映射关系。你可以通过修 改./development/emulator/keymaps/qwerty.kl来改变键值的映射关系。

JNI 函数

C代码：

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调用hub->getEvent读了取事件，然后转换成JAVA的结构。

事件中转线程

在frameworks/base/services/java/com/android/server/KeyInputQueue.java 里创建了一个线程，它循环的读取事件，然后把事件放入事件队列里。

Java代码:

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;

// block, doesn't release the monitor
readEvent(ev);

boolean send = false;
boolean configChanged = false;

if (false) {
Log.i(TAG, "Input event: dev=0x"
+ Integer.toHexString(ev.deviceId)
+ " type=0x" + Integer.toHexString(ev.type)
+ " scancode=" + ev.scancode
+ " keycode=" + ev.keycode
+ " value=" + ev.value);
}

if (ev.type == RawInputEvent.EV_DEVICE_ADDED) {
synchronized (mFirst) {
di = newInputDevice(ev.deviceId);
mDevices.put(ev.deviceId, di);
configChanged = true;
}
}

　　　　　　　　　　　　......
　　　　　　　　　　}
　　　　　　　　}
　　　　　　}
};