1. protected-broadcast applications using the system components specification custom broadcast
Reference: https: //blog.csdn.net/TaylorPotter/article/details/70194248
2.Android of BroadcastReceiver (IV): using local broadcast
Reference: https: //blog.csdn.net/lj2012sy/article/details/51688985
3.Android Broadcast rights and restrictions BroadcastReceiver
Reference: https: //blog.csdn.net/javensun/article/details/7334230
Detailed property 4.android:exported
Reference: https: //blog.csdn.net/watermusicyes/article/details/46460347