问题
I googled it and couldn't find a definition. As usual the Android documentation was very "illuminating".
回答1:
In a nutshell, it is your lockscreen.
PIN, pattern, face, password locks or the default lock (slide to unlock), but it is your lock screen.
回答2:
Keyguard basically refers to the code that handles the unlocking of the phone. it's like the keypad lock on your nokia phone a few years back just with the utility on a touchscreen.
you can find more info it you look in android/app or com\android\internal\policy\impl
Good Luck !
回答3:
The lock screen works without keyguard i have tested it. The home button stops working and you can't get to task manager by holding the home key. I wish they didn't develop a new process when it used to be built into system ui or whatever. I don't see the need for the change and extra process
回答4:
Yes, I also found it here: http://developer.android.com/tools/testing/activity_testing.html It's seems a key-input protection mechanism which includes the screen-lock, but not only includes it. According to this webpage, it also defines some key-input restriction for auto-test framework in Android.
来源：https://stackoverflow.com/questions/17689842/what-is-the-keyguard-in-android