无法添加窗口android.view.ViewRootImpl$W@53e1e83-窗口类型2038的权限被拒绝

Question

添加TYPE_APPLICATION_OVERLAY并在OREO中运行时出现错误，如何解决我的错误，请帮助

这是我的代码

        WindowManager.LayoutParams params = getWindow().getAttributes();
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
          params.type = WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY;
        }
        else
        {
          params.type = WindowManager.LayoutParams.TYPE_SYSTEM_ERROR;
        }
        params.dimAmount = 0.0F; // transparent
        params.width = 0;
        params.height = 0;
        params.gravity = Gravity.BOTTOM;
        getWindow().setAttributes(params);
        getWindow().setFlags(FLAG_SHOW_WHEN_LOCKED | FLAG_NOT_TOUCH_MODAL, 0xffffff);
        setOwnerActivity(activity);
        setCancelable(false);

这个错误

    android.view.WindowManager$BadTokenException: Unable to add window 
    android.view.ViewRootImpl$W@53e1e83 -- permission denied for window type 2038
    at android.view.ViewRootImpl.setView(ViewRootImpl.java:1093)
    at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:381)
    at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:93)

请帮忙...