Swing——JButton美化

关于美化JButton，先结合一个实例说吧。

package test;

import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.Shape;
import java.awt.geom.RoundRectangle2D;

import javax.swing.AbstractButton;
import javax.swing.JComponent;
import javax.swing.plaf.basic.BasicButtonUI;

public class MyButtonUI extends BasicButtonUI{
 private static final Color BUTTON_COLOR1 = new Color(205,255,205);
 private static final Color BUTTON_COLOR2 = new Color(51,154,47);
 public MyButtonUI(){
  super();
 }
 public void paint(Graphics g,JComponent c){
  super.paint(g, c);
  Graphics2D g2d=(Graphics2D)g;
  int h=c.getHeight();
  int w=c.getWidth();
  float tran=1F;
  g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,RenderingHints.VALUE_ANTIALIAS_ON);
  GradientPaint p1;
  GradientPaint p2;
  p1=new GradientPaint(0,0,new Color(0,0,0), 0,h-1,new Color(100,100,100));
  p2=new GradientPaint(0,1,new Color(0,0,0,50),0,h-3,new Color(255,255,255,100));
  g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER,tran));
  RoundRectangle2D.Float r2d=new RoundRectangle2D.Float(0,0,w-1,h-1,20,20);
  Shape clip=g2d.getClip();
  g2d.clip(r2d);
  GradientPaint gp=new GradientPaint(0.0F,0.0F,BUTTON_COLOR1,0.0F,h,BUTTON_COLOR2,true);
  g2d.setPaint(gp);
  g2d.fillRect(0,0,w,h);
  g2d.setClip(clip);
  g2d.setPaint(p1);
  g2d.drawRoundRect(0,0,w-1,h-1,20,20);
  g2d.setPaint(p2);
  g2d.drawRoundRect(1,1,w-3,h-3,18,18);
 }
}

这段代码的所显示的按钮如下图所示

但是很多时候绘制出来的按钮都有一个矩形的边框，那么如何去掉它呢？答案很简单，就是创建button的时候调用对象的setBorderPainted(false)以及setContentAreaFilled(false),setBorderPainter(false)设完了不就可以了，但为什么还要后面的setContentAreaFilled(false)呢？

这个是因为在重载BasicButtonUI的时候，重载方法intallUI()的时候往往需要设置Button的默认属性值，比如setBackground()，在设置ContentAreaFilled(false)后，这些属性值就都看不到了,所以我们看到的就是不同形状的按钮了。是不是很厉害？但是别忘了，此时的button还没有原来默认按钮按下就有边框的功能，此时我们重载BasicButtonUI的paintButtonPressed()方法,并微调一些数值，代码如下

@Override
 protected void paintButtonPressed(Graphics g,AbstractButton b){
  super.paintButtonPressed(g, b); 
  Graphics2D g2d=(Graphics2D)g;
  int h=b.getHeight();
  int w=b.getWidth();
  float tran=1F;
  g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,RenderingHints.VALUE_ANTIALIAS_ON);
  GradientPaint p1;
  GradientPaint p2;
  p1=new GradientPaint(0,0,new Color(0, 0, 0), 0,h-1,new Color(100,100,100));
  p2=new GradientPaint(0,1,new Color(0,0,0,50),0,h-3,new Color(255,255,255,100));
  g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER,tran));
  RoundRectangle2D.Float r2d=new RoundRectangle2D.Float(0,0,w-1,h-1,20,20);
  Shape clip=g2d.getClip();g2d.clip(r2d);
  GradientPaint gp=new GradientPaint(0.0F,0.0F,BUTTON_COLOR1,0.0F,h,BUTTON_COLOR2,true);
  g2d.setPaint(gp);
  g2d.fillRect(0,0,w,h);
  g2d.setClip(clip);
  g2d.setPaint(p1);
  g2d.drawRoundRect(0,0,w-2,h-2,20,20);
  g2d.setPaint(p2);
  g2d.drawRoundRect(1,1,w-4,h-4,18,18);
  g2d.dispose();
 }

这样按下按钮的时候就有反应了，具体效果如图。

通过自定义BasicButtonUI我们就可以绘制各种不同形状的按钮，自定义完成后不要忘记setUI()哦，这样才能看到你自定义的按钮的形状哦！！！