public @StartResult int onStartCommand(Intent intent, @StartArgFlags int flags, int startId) {
onStart(intent, startId);
有四種傳回值:
1.START_STICKY
service會重新開機,調用oncreate onStartCommand(),但是startId會改變
2.START_NO_STICKY
service不會重新開機。
3.START_STICKY_COMPATIBILITY
service會重新開機,但是隻調用onCreate()
4.START_REDELIVER_INTENT
service會重新開機,調用onCreate(),onStartCommand(),startId不變,intent也不為空