原文地址：https://www.jianshu.com/p/4c5fafe08fa7
android.view.WindowManager$BadTokenException的4种情形：
1.Unable to add window --token null is not valid; is your activity running
**2.Unable to add window --token null is not for an application **
3.Unable to add window -- token android.os.BinderProxy@XXX is not valid;
is your activity running
**4.Unable to add window -- token android.app.LocalActivityManager
$LocalActivityRecord @xxx is not valid; is your activity running
