【方法教程】Swing 自定义 JScrollPane 的滚动条设置, 重写 BasicScrollBarUI 方法

1.自定义 BasicScrollBarUI 类

package com.melec.vo.view;
import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.RenderingHints;


import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JScrollBar;
import javax.swing.plaf.basic.BasicScrollBarUI;



/**

 * 自定义滚动条UI

 *

 * @author zsg

 */

public class DemoScrollBarUI extends BasicScrollBarUI {

    @Override
    protected void configureScrollBarColors() {

        // 把手

        // thumbColor = Color.GRAY;

        // thumbHighlightColor = Color.BLUE;

        // thumbDarkShadowColor = Color.BLACK;

        // thumbLightShadowColor = Color.YELLOW;

        // 滑道

        trackColor = Color.black;

        setThumbBounds(0, 0, 3, 10);

        // trackHighlightColor = Color.GREEN;

    }

    /**

     * 设置滚动条的宽度

     */

    @Override
    public Dimension getPreferredSize(JComponent c) {

        // TODO Auto-generated method stub

        c.setPreferredSize(new Dimension(40, 0));

        return super.getPreferredSize(c);

    }


    // 重绘滑块的滑动区域背景

    public void paintTrack(Graphics g, JComponent c, Rectangle trackBounds) {

        Graphics2D g2 = (Graphics2D) g;

        GradientPaint gp = null;

        //判断滚动条是垂直的 还是水平的

        if (this.scrollbar.getOrientation() == JScrollBar.VERTICAL) {

            //设置画笔

            gp = new GradientPaint(0, 0, new Color(80, 80, 80),

                    trackBounds.width, 0, new Color(80, 80, 80));

        }

        if (this.scrollbar.getOrientation() == JScrollBar.HORIZONTAL) {

            gp = new GradientPaint(0, 0, new Color(80, 80, 80),

                    trackBounds.height, 0, new Color(80, 80, 80));

        }


        g2.setPaint(gp);

        //填充Track

        g2.fillRect(trackBounds.x, trackBounds.y, trackBounds.width,

                trackBounds.height);

        //绘制Track的边框
        /*       g2.setColor(new Color(175, 155, 95));
         g2.drawRect(trackBounds.x, trackBounds.y, trackBounds.width - 1,
                trackBounds.height - 1);
                */

        if (trackHighlight == BasicScrollBarUI.DECREASE_HIGHLIGHT)

            this.paintDecreaseHighlight(g);

        if (trackHighlight == BasicScrollBarUI.INCREASE_HIGHLIGHT)

            this.paintIncreaseHighlight(g);

    }


    @Override
    protected void paintThumb(Graphics g, JComponent c, Rectangle thumbBounds) {

        // 把绘制区的x，y点坐标定义为坐标系的原点

        // 这句一定一定要加上啊，不然拖动就失效了

        g.translate(thumbBounds.x, thumbBounds.y);

        // 设置把手颜色

        g.setColor(new Color(	230,230,250));

        // 画一个圆角矩形

        // 这里面前四个参数就不多讲了，坐标和宽高

        // 后两个参数需要注意一下，是用来控制角落的圆角弧度

        // g.drawRoundRect(0, 0, 5, thumbBounds.height - 1, 5, 5);

        // 消除锯齿

        Graphics2D g2 = (Graphics2D) g;

        RenderingHints rh = new RenderingHints(RenderingHints.KEY_ANTIALIASING,

                RenderingHints.VALUE_ANTIALIAS_ON);

        g2.addRenderingHints(rh);

        // 半透明

        g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER,

                0.5f));

        // 设置填充颜色，这里设置了渐变，由下往上

        // g2.setPaint(new GradientPaint(c.getWidth() / 2, 1, Color.GRAY,

        // c.getWidth() / 2, c.getHeight(), Color.GRAY));

        // 填充圆角矩形

        g2.fillRoundRect(0, 0, 40, thumbBounds.height - 1, 5, 5);

    }


    /**

     * 创建滚动条上方的按钮

     */

    @Override

    protected JButton createIncreaseButton(int orientation) {

        JButton button = new JButton();

        button.setBorderPainted(false);

        button.setContentAreaFilled(false);

        button.setBorder(null);

        return button;

    }

    /**

     * 创建滚动条下方的按钮

     */

    @Override

    protected JButton createDecreaseButton(int orientation) {

        JButton button = new JButton();

        button.setBorderPainted(false);

        button.setContentAreaFilled(false);

        button.setFocusable(false);

        button.setBorder(null);

        return button;

    }

}

2.使用自定义类,覆盖 JScrollPane 滚动条样式

 JScrollPane scrollPane = new JScrollPane();
 scrollPane.getVerticalScrollBar().setUI(new DemoScrollBarUI());