直接设置pupupwindow 所引用的view的透明度即可
如
LayoutInflater layoutInflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
popupMoreMenuView = layoutInflater.inflate(R.layout.test);
popupMoreMenuWindow = new PopupWindow(popupMoreMenuView,
LinearLayout.LayoutParams.WRAP_CONTENT,
LinearLayout.LayoutParams.WRAP_CONTENT);
popupMoreMenuView.setAlpha(0.9f);//90%透明度
