swing重绘按钮为任意形状图案的方法

import javax.imageio.ImageIO; import javax.swing.*; import java.awt.*; import java.awt.image.BufferedImage;  public class newButton extends JButton{  ImageIcon img;  public newButton(String icon){   super();   this.img = new ImageIcon(Demo.class.getResource(icon));   setBorderPainted(false);   setContentAreaFilled(false);   setOpaque(false);   setSize(img.getIconWidth(),img.getIconHeight());   try{    bi = ImageIO.read(Demo.class.getResource(icon));   }catch(Exception e){    JOptionPane.showMessageDialog(this,"可能是图片文件不存在","ImageIO异常",JOptionPane.ERROR_MESSAGE);    System.exit(0);   }  }  @Override  public void paintComponent(Graphics g){   if(this.getModel().isPressed()){    g.drawImage(img.getImage(),1,1,this);   }else{    g.drawImage(img.getImage(),0,0,this);   }   super.paintComponent(g);  }  BufferedImage bi ;  int rgb,alpha;  /**   * 设置按钮点击范围仅在图片的非透明区域。   */  @Override  public boolean contains(int x,int y){   try{    rgb = bi.getRGB(x,y);    alpha = (rgb>>24)&0xFF;    if(alpha==0){     return false;    }else{     return true;    }   }catch(ArrayIndexOutOfBoundsException e){    //当搜索到透明区域时，就getRGB抛出下表越界异常    return false;   }  } } 

import javax.swing.*; import java.awt.*; import java.net.URL;  public class Demo {  public Demo(){   JFrame jf=new JFrame("任意形状图片按钮测试");   jf.setBounds(500,200,700,500);    myJPanel jp = new myJPanel(Demo.class.getResource("bg.jpg"));   jp.setLayout(null);    newButton jb1 = new newButton("bt1.png");   jb1.setLocation(44,44);   jp.add(jb1);    jb1 = new newButton("snowFlower.png");   jb1.setLocation(200,44);   jp.add(jb1);    jb1 = new newButton("bt2.png");   jb1.setLocation(350,64);   jp.add(jb1);    jb1 = new newButton("bt3.png");   jb1.setLocation(450,64);   jp.add(jb1);    jf.add(jp);   jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);   jf.setVisible(true);  }  public static void main(String[] args){   new Demo();  }  private class myJPanel extends JPanel{   ImageIcon bg;   public myJPanel(URL bg) {    this.setOpaque(false);//要设置为透明。    this.bg = new ImageIcon(bg);   }   //用于设置背景图片   @Override   public void paintComponent(Graphics g){    g.drawImage(bg.getImage(),0,0,this.getWidth(),this.getHeight(),this);    super.paintComponent(g);   }  } }