Swing中Laber添加下划线

下划线的颜色可以单独定义

import java.awt.*;
import javax.swing.*;
import javax.swing.border.LineBorder;

public class JLabelUnderLinePerfect extends JLabel {

	private Color underLineColor;

	public JLabelUnderLinePerfect() {
		this("");
	}

	public JLabelUnderLinePerfect(String text) {
		super(text);
	}

	public Color getUnderLineColor() {
		return underLineColor;
	}

	public void setUnderLineColor(Color pUnderLineColor) {
		underLineColor = pUnderLineColor;
	}

	public void paint(Graphics g) {
		super.paint(g);

		Rectangle r = g.getClipBounds();
		int xoffset = 0, yoffset = 0, pointX = 0, pointY = 0, point2X = 0, point2Y = 0;

		// 根据border的设置 计算出下划线的起止Point
		if (null != this.getBorder()
				&& null != this.getBorder().getBorderInsets(this)) {
			Insets inserts = this.getBorder().getBorderInsets(this);
			xoffset = inserts.left;
			yoffset = inserts.bottom;
		}
		pointX = xoffset;
		pointY = point2Y = r.height - yoffset
				- getFontMetrics(getFont()).getDescent();
		point2X = pointX + getFontMetrics(getFont()).stringWidth(getText());
		if (null != underLineColor) {
			g.setColor(underLineColor);
		}

		g.drawLine(pointX, pointY, point2X, point2Y);
	}

	public static void main(String[] args) {
		JFrame f = new JFrame("JLabe with Under Line");
		f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		f.setSize(new Dimension(300, 200));
		f.setLayout(new FlowLayout());

		JLabelUnderLinePerfect label1 = new JLabelUnderLinePerfect("Label下划线");
		f.add(label1);

		JLabelUnderLinePerfect label2 = new JLabelUnderLinePerfect("Label下划线");
		label2.setUnderLineColor(Color.BLUE);
		f.add(label2);

		JLabelUnderLinePerfect label3 = new JLabelUnderLinePerfect(
				"Label(Border)下划线");
		label3.setBorder(BorderFactory.createCompoundBorder(new LineBorder(
				Color.RED), BorderFactory.createEmptyBorder(8, 18, 28, 38)));
		label3.setUnderLineColor(Color.BLUE);
		f.add(label3);

		// f.pack();
		f.setVisible(true);

	}
}