首先，简要的介绍一下按键的处理流程。先简单的分为两大类：一类是虚拟按键。另一类是物理按键。

普通按键盘流程

HAL层

./hardware/libhardware_legacy/power/power.c

set_screen_state(int on)

hal层按键休眠和唤醒

JNI层

frameworks/base/core/jni/android_os_Power.cpp

static int
setScreenState(JNIEnv *env, jobject clazz, jboolean on)
{
return set_screen_state(on);
}

JAVA层

frameworks/base/core/java/android/os/Power.java

public static native int setScreenState(boolean on);

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

为APP层提供以下接口

public void goToSleep(long time)==》public void goToSleepWithReason(long time, int reason)==》private void goToSleepLocked(long time, int reason)==》private void setPowerState(int state)==》