java的Graphics2D的drawString()方法写不出下滑线

Graphics2D graphics = image.createGraphics();
			// 设置笔刷白色
			graphics.setColor(Color.white);
			// 填充整个屏幕
			graphics.fillRect(0, 0, greWidth, greHeight);
			graphics.drawLine(0, 0, greWidth, greHeight);

			int preY = 0;
			for (QrcodeFont text : texts) {
				graphics.setColor(text.getColor());
				graphics.setFont(getFont(text.getFontSize()));
				text.setStartY(text.getStartY() == 0 ? preY + DEFAULT_FONT_SIZE + 1 : text.getStartY());
				graphics.drawString(new String(text.getText().getBytes(),"utf-8"), text.getStartX(), text.getStartY());
				preY = text.getStartY();
			}

这个方法文字能正常显示，但是_这种下滑线画不出来，怎么才能让下滑线显示出来