swing自定义JSlider

JSlider作为Swing中提供的滑标组件， 以图形方式在有界区间内通过移动滑块来选择值，滑块可以显示主刻度标记和次刻度标记。大量应用于如播放器中的音量设定等领域中。

但是JSlider本身提供的UI样式很单调，不足以满足用户的审美需求，往往需要我们自行重构其UI。

下面我给出一个简单的例子。

package org.loon.framework.swing.test;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Polygon;
import java.awt.Rectangle;
import java.awt.RenderingHints;

import javax.swing.Box;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JSlider;
import javax.swing.WindowConstants;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;

/** *//**
* <p>
* Title: LoonFramework
* </p>
* <p>
* Description:
* </p>
* <p>
* Copyright: Copyright (c) 2007
* </p>
* <p>
* Company: LoonFramework
* </p>
*
* @author chenpeng
* @email：[e-mail]
* @version 0.1
*/
public class ExampleSlider extends JPanel ...{
    /** *//**
     *
     */
    private static final long serialVersionUID = 1L;

    public ExampleSlider() ...{
        // 设定布局器
        super(new BorderLayout());
        // 设定监听器
        ChangeListener listener = new ChangeListener() ...{
            public void stateChanged(ChangeEvent e) ...{
                if (e.getSource() instanceof JSlider) ...{
                    System.out.println("刻度: "
                            + ((JSlider) e.getSource()).getValue());
                }
            }
        };
        // 设定JSlider1
        JSlider s1 = new JSlider(0, 100, 0);
        // 注入自定义ui
        s1.setUI(new MySliderUI());
        // 主刻度
        s1.setMajorTickSpacing(10);
        // 次刻度
        s1.setMinorTickSpacing(5);
        // 设定为显示
        s1.setPaintTicks(true);
        s1.setPaintLabels(true);
        // 监听slider1
        s1.addChangeListener(listener);
        // 设定JSlider2
        JSlider s2 = new JSlider(0, 100, 0);
        // 使用MetalSliderUI为ui
        s2.setUI(new javax.swing.plaf.metal.MetalSliderUI() ...{
            protected void paintHorizontalLabel(Graphics g, int v, Component l) ...{
                JLabel lbl = (JLabel) l;
                lbl.setForeground(Color.green);
                super.paintHorizontalLabel(g, v, lbl);
            }
        });
       
        s2.setForeground(Color.BLUE);
        s2.setMajorTickSpacing(10);
        s2.setMinorTickSpacing(5);
        s2.setPaintTicks(true);
        s2.setPaintLabels(true);
        s2.addChangeListener(listener);

        //使用盒式容器
        Box box = Box.createVerticalBox();
        box.add(Box.createVerticalStrut(5));
        box.add(s1);
        box.add(Box.createVerticalStrut(5));
        box.add(s2);
        box.add(Box.createVerticalGlue());
        add(box, BorderLayout.CENTER);
        add(Box.createHorizontalStrut(5), BorderLayout.WEST);
        add(Box.createHorizontalStrut(5), BorderLayout.EAST);
        //设定窗体大小
        setPreferredSize(new Dimension(240, 100));
    }

    public static void main(String[] args) ...{
        EventQueue.invokeLater(new Runnable() ...{
            public void run() ...{
                createUI();
            }
        });
    }

    public static void createUI() ...{
        JFrame frame = new JFrame("音量刻度设置");
        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        frame.getContentPane().add(new ExampleSlider());
        frame.setResizable(false);
        frame.pack();
        //居中
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }
}

class MySliderUI extends javax.swing.plaf.metal.MetalSliderUI ...{
    /** *//**
     * 绘制指示物
     */
    public void paintThumb(Graphics g) ...{
        Graphics2D g2d = (Graphics2D) g;
        g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        //填充椭圆框为当前thumb位置
        g2d.fillOval(thumbRect.x, thumbRect.y, thumbRect.width,
                        thumbRect.height);
        //也可以帖图(利用鼠标事件转换image即可体现不同状态)
        //g2d.drawImage(image, thumbRect.x, thumbRect.y, thumbRect.width,thumbRect.height,null);
    }

    /** *//**
     * 绘制刻度轨迹
     */
    public void paintTrack(Graphics g) ...{
        int cy, cw;
        Rectangle trackBounds = trackRect;
        if (slider.getOrientation() == JSlider.HORIZONTAL) ...{
            Graphics2D g2 = (Graphics2D) g;
            cy = (trackBounds.height / 2) - 2;
            cw = trackBounds.width;

            g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                    RenderingHints.VALUE_ANTIALIAS_ON);
            g2.translate(trackBounds.x, trackBounds.y + cy);

            // 背景设为灰色
            g2.setPaint(Color.GRAY);
            g2.fillRect(0, -cy, cw, cy * 2);

            int trackLeft = 0;

            int trackRight = 0;

            trackRight = trackRect.width - 1;

            int middleOfThumb = 0;

            int fillLeft = 0;

            int fillRight = 0;

            //坐标换算
            middleOfThumb = thumbRect.x + (thumbRect.width / 2);
            middleOfThumb -= trackRect.x;

            if (!drawInverted()) ...{
                fillLeft = !slider.isEnabled() ? trackLeft : trackLeft + 1;
                fillRight = middleOfThumb;
            } else ...{
                fillLeft = middleOfThumb;
                fillRight = !slider.isEnabled() ? trackRight - 1
                        : trackRight - 2;
            }
            // 设定渐变
            g2.setPaint(new GradientPaint(0, 0, new Color(0, 100, 100), cw, 0,
                    new Color(0, 255, 100), true));
            g2.fillRect(0, -cy, fillRight - fillLeft, cy * 2);

            g2.setPaint(slider.getBackground());
            Polygon polygon = new Polygon();
            polygon.addPoint(0, cy);
            polygon.addPoint(0, -cy);
            polygon.addPoint(cw, -cy);
            g2.fillPolygon(polygon);
            polygon.reset();

            g2.setPaint(Color.WHITE);
            g2.drawLine(0, cy, cw - 1, cy);

            g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                    RenderingHints.VALUE_ANTIALIAS_OFF);
            g2.translate(-trackBounds.x, -(trackBounds.y + cy));
        } else ...{
            super.paintTrack(g);
        }
    }
}


效果图：



原文出自 “Java究竟怎么玩” 博客http://cping1982.blog.51cto.com/601635/130163