对于大部分人来说，Java默认的slider实在是不忍心用，因为太难看了。虽然说它难看，但是他确实最基本的，最基础的，Java中，所有美化后的JSlider都是通过更改这个最基本的UI之后得来的。所以，从某一方面讲，他却又是最重要的。
美化JSlider，主要通过 public void paintThumb() 以及public void paintTrack()，这里为什么不用paint()方法呢？答案很简单，因为paint()方法通过间接调用这两个方法而进行绘制，也就是说，paint()方法里面包含这两个方法。所以直接重写这两个方法就OK啦！
public void paint( Graphics g, JComponent c ) { recalculateIfInsetsChanged(); recalculateIfOrientationChanged(); Rectangle clip = g.getClipBounds(); if ( !clip.intersects(trackRect) && slider.getPaintTrack()) calculateGeometry(); if ( slider.getPaintTrack() && clip.intersects( trackRect ) ) { paintTrack( g ); } if ( slider.getPaintTicks() && clip.intersects( tickRect ) ) { paintTicks( g ); } if ( slider.getPaintLabels() && clip.intersects( labelRect ) ) { paintLabels( g ); } if ( slider.hasFocus() && clip.intersects( focusRect ) ) { paintFocus( g ); } if ( clip.intersects( thumbRect ) ) { paintThumb( g ); }}
上面为BasicSliderUI中的一部分，是不是可以看出paint()调用了paintThumb()以及piantTrack()？下面我们来绘制一个好看的Slider！
代码如下：
public class MySliderUI extends BasicSliderUI{ private static final Color BACKGROUND01=new Color(0,30,255); private static final Color BACKGROUND02=new Color(234,236,246); public MusicSliderUI01(JSlider arg0) { super(arg0); } @Override public void paintThumb(Graphics g){ Graphics2D g2d=(Graphics2D) g; BasicStroke stroke=new BasicStroke(1,BasicStroke.CAP_ROUND,BasicStroke.JOIN_ROUND); g2d.setStroke(stroke); g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER,0.5f)); g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); GradientPaint gp=new GradientPaint(0,0,BACKGROUND02,0,thumbRect.height,BACKGROUND01); g2d.setPaint(gp); g2d.fillRoundRect(thumbRect.x, thumbRect.y, thumbRect.width, thumbRect.height, 10, 10); BasicStroke stroke1=new BasicStroke(3,BasicStroke.CAP_ROUND,BasicStroke.JOIN_ROUND); g2d.setStroke(stroke1); g2d.drawLine(8, thumbRect.height/2,thumbRect.x+8 , thumbRect.height/2); } @Override public void paintTrack(Graphics g){ Graphics2D g2d=(Graphics2D) g; // 设定渐变 g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_OFF); g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER,0.3f)); g2d.setPaint(new GradientPaint(0, 0,BACKGROUND02 , 0,trackRect.height, BACKGROUND01, true)); g2d.setStroke(new BasicStroke(4,BasicStroke.CAP_ROUND,BasicStroke.JOIN_ROUND)); g2d.drawLine(8, trackRect.height/2+1, trackRect.width+8, trackRect.height/2+1); } }
这是效果图，是不是好看很多？大家也可以试着自己美化一下哦！！！
