??????ó???????????ó????????permissions???package installer??????????package installer?????????ó??????????????????ó???????????????????ù????в???????????????????????????????????????????????;????????????????????????????feature??????????κ?????????????????????????????????????????????????????y??????????????

???????磬?????system????????趨??api??????apk???system?????????? android ??API????SystemClock.setCurrentTimeMillis()??????????????????????????

???? ??????????????????????Android?????????????make??????

????1. ????ó????AndroidManifest.xml?е?manifest??????android:sharedUserId="android.uid.system"????????

????2. ???Android.mk?????????LOCAL_CERTIFICATE := platform

????3. ???mm???????????????apk???????????????Χ???

???? ??2????????

????1. ????????android:sharedUserId="android.uid.system"????????

????2. ???eclipse?????apk????????????apk????????????

????3. ???????platform???????????apk????????????signapk platform.x509.pem platform.pk8 input.apk output.apk