private static native void nativeShutdown(); private static native void nativeReboot(String reason) throws IOException;
5.frameworks/base/services/jni/com_android_server_PowerManagerService.cpp
static JNINativeMethod gPowerManagerServiceMethods[] = {
/* name, signature, funcPtr */
...
{ "nativeShutdown", "()V",
(void*) nativeShutdown },
{ "nativeReboot", "(Ljava/lang/String;)V",
(void*) nativeReboot },
...
};
这两个好哥俩的实现也是在一起的：
static void nativeShutdown(JNIEnv *env, jobject clazz) {
android_reboot(ANDROID_RB_POWEROFF, 0, 0);
}
static void nativeReboot(JNIEnv *env, jobject clazz, jstring reason) {
if (reason == NULL) {
android_reboot(ANDROID_RB_RESTART, 0, 0);
} else {
const char *chars = env->GetStringUTFChars(reason, NULL);
android_reboot(ANDROID_RB_RESTART2, 0, (char *) chars);
env->ReleaseStringUTFChars(reason, chars); // In case it fails.
}
jniThrowIOException(env, errno);
}
可以看到无论是关机还是重启，都是调用android_reboot来实现的，只是参数不一样而已。
6.system/core/libcutils/android_reboot.c
int android_reboot(int cmd, int flags, char *arg)
{
int ret = 0;
int reason = -1;
#ifdef RECOVERY_PRE_COMMAND
if (cmd == (int) ANDROID_RB_RESTART2) {
if (arg && strlen(arg) > 0) {
char cmd[PATH_MAX];
sprintf(cmd, RECOVERY_PRE_COMMAND " %s", arg);
system(cmd);
}
}
#endif
if (!(flags & ANDROID_RB_FLAG_NO_SYNC))
sync();
if (!(flags & ANDROID_RB_FLAG_NO_REMOUNT_RO))
remount_ro();
switch (cmd) {
case ANDROID_RB_RESTART:
reason = RB_AUTOBOOT;
break;
case ANDROID_RB_POWEROFF:
ret = reboot(RB_POWER_OFF);
return ret;
case ANDROID_RB_RESTART2:
// REBOOT_MAGIC
break;
default:
return -1;
}
#ifdef RECOVERY_PRE_COMMAND_CLEAR_REASON
reason = RB_AUTOBOOT;
#endif
if (reason != -1)
ret = reboot(reason);
else
ret = __reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2,
LINUX_REBOOT_CMD_RESTART2, arg);
return ret;
}
