java 怎么给 Jlabel 添加边框

public class LabelUI extends BasicLabelUI{

@Override

public void paint(Graphics g, JComponent c) {

// TODO Auto-generated method stub

g.setColor(Color.BLACK)

int y = (int) c.getSize().getHeight()

int x = (int) c.getSize().getWidth()

System.out.println(x+" "+y)

g.drawLine(0, y-1, x-1, y-1)

g.drawLine(x-1, 0, x-1, y-1)

super.paint(g, c)

}

}

JLabel是默认透明的

JLabel jl = new JLabel("This is a JLabel")

jl.setOpaque(false)//是不是前面设true了

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