android 创建系统dialog

AlertDialog.Builder dialogBuilder = new AlertDialog.Builder(context);
            LayoutInflater inflater = ((Activity)context).getLayoutInflater();
            dialogBuilder.setView(inflater.inflate(R.layout.dialog_signin, null));
            dialogBuilder.setCancelable(false);
            AlertDialog alertDialog = dialogBuilder.create();

            if (Build.VERSION.SDK_INT > Build.VERSION_CODES.O){
                WindowManager.LayoutParams params = new WindowManager.LayoutParams();
                params.type = WindowManager.LayoutParams.TYPE_PHONE;
                alertDialog.onWindowAttributesChanged(params);
            }else {
                WindowManager.LayoutParams params = new WindowManager.LayoutParams();
                params.type = WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY;
                alertDialog.onWindowAttributesChanged(params);
            }
            alertDialog.show();