何时Android触发Intent.ACTION_USER_PRESENT广播？
如题。
[解决办法]
public static final String ACTION_USER_PRESENT
Since: API Level 3
Broadcast Action: Sent when the user is present after device wakes up (e.g when the keyguard is gone).
This is a protected intent that can only be sent by the system.
Constant Value: "android.intent.action.USER_PRESENT"
