Frameworks 中显示对话框

一般的对话框在activity中都能显示，那么在frameworks中去显示就会提示这样的错误

08-13 04:49:06.544  9066  9066 E AndroidRuntime: Caused by: android.view.WindowManager$BadTokenException: Unable to add window -- token null is not valid; is your activity running?

只有一行代码就能解决

            if (!(mContext instanceof Activity)) {mDialog.getWindow().setType(WindowManager.LayoutParams.TYPE_SYSTEM_ALERT);}

type是你对话框显示的层级。