Override JButton paintComponent() doesn't work

问题:

I wanted to paint my own version of JButton, so I have overridden the paintComponent() method, and drew a gradient roundRect. This works, but after that, I want to draw the String of the Button over it, and at compile-time, I got no error messages. But at runtime, I only see the roundRect, gradient, just as I intended it to be (I can click on it too), but the String is invisible...

Here's my code:

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

public class JIconButton extends JButton implements MouseListener
{
    private boolean mouseInside;
    public JIconButton(String file, String text)
    {
        super(text, new ImageIcon(file));
        setBorder(new LineBorder(Color.LIGHT_GRAY, 0, true));
        setContentAreaFilled(false);
        setFocusPainted(false);
        addMouseListener(this);
        setVisible(true);
    }

    public void mouseClicked(MouseEvent e)
    {

    }

    public void mouseEntered(MouseEvent e)
    {

    }

    public void mouseExited(MouseEvent e)
    {

    }

    public void mousePressed(MouseEvent e)
    {

    }

    public void mouseReleased(MouseEvent e) 
    {

    }

    @Override
    protected void paintComponent(Graphics g)
    {
        Graphics2D g2 = (Graphics2D)g.create();
        g2.setPaint(Color.BLACK);
        g2.drawString(getText(), 0, 0);
        g2.setPaint(new GradientPaint(
                new Point(0, 0), 
                Color.WHITE, 
                new Point(0, getHeight()), 
                Color.PINK.darker()));
        g2.fillRoundRect(0, 0, getWidth(), getHeight(), 30, 30);
        g2.dispose();

        //super.paintComponent(g);
    }
}

回答1:

As per my comment, "it worked for me...."
For example:

   @Override
   protected void paintComponent(Graphics g) {
      Graphics2D g2 = (Graphics2D) g.create();
      g2.setPaint(new GradientPaint(new Point(0, 0), Color.WHITE, new Point(0,
            getHeight()), Color.PINK.darker()));
      g2.fillRoundRect(0, 0, getWidth(), getHeight(), 30, 30);
      g2.setPaint(Color.BLACK);
      g2.drawString(getText(), 30, 12);
      g2.dispose();

      // super.paintComponent(g);
   }

回答2:

You have to do:

g2.drawString(getText(), 0, 10);

the y of the string coordinate must be greater than 0, because is the starting point of the baseline and not the point of the upper left corner of a box. The final code:

@Override
protected void paintComponent(Graphics g) {
  Graphics2D g2 = (Graphics2D) g.create();
  g2.setPaint(new GradientPaint(
  new Point(0, 0),
    Color.WHITE,
    new Point(0, getHeight()),
    color.PINK.darker()));
  g2.fillRoundRect(0, 0, getWidth(), getHeight(), 30, 30);
  // The drawString(string) must be put after the setPaint(gradient)
  g2.setPaint(Color.BLACK);
  g2.drawString(getText(), 0, 10);
  g2.dispose();
}

回答3:

1) easiest way would be JButton's methods JButton(String text, Icon icon) example here

2) you can override XxxButtonUI, or change GradientButton