问题
Android Oreo introduces notification channels, but the documentation for how to specify a default notification channel in the application manifest seems to be patchy to nonexistent.
How do you specify a default notification channel ID in the application manifest?
回答1:
Defining a default channel ID from the manifest cannot be done with standard notification channels, it only applies to Firebase notifications: Firebase: How to set default notification channel in Android app?
来源：https://stackoverflow.com/questions/46591282/how-do-you-specify-a-default-notification-channel-id-in-the-application-manifest