TextView------文字底部或者中间加横线

promotionLinkText = (TextView) this .findViewById(R.id. text_promotion_link );

中间加横线
promotionLinkText .getPaint().setFlags(Paint. STRIKE_THRU_TEXT_FLAG );

底部加横线：
promotionLinkText .getPaint().setFlags(Paint. UNDERLINE_TEXT_FLAG );