关于params

RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(
                new LayoutParams(100,LayoutParams.FILL_PARENT));
        ivTabNow.setBackgroundColor(getResources().getColor(R.color.bg));
        params.addRule(RelativeLayout.CENTER_IN_PARENT,
                RelativeLayout.TRUE);// 居于屏幕中间 
        
        ly.addView(ivTabNow, params);