java中JLabel设置背景图片

 先贴代码，再看注释；

//显示图片的JLabel
          ImageIcon background =new ImageIcon(test.class.getResource("jpanel_pci.jpg"));//test为当前的类，jpanel_pci.jpg自动添加到当前项目的包中
          background.setImage(
        		  background.getImage().
        		  getScaledInstance(background.getIconWidth(),background.getIconHeight(), Image.SCALE_DEFAULT));  
          /****
           * @author Administrator
           * getScaledInstance(width,height,hints);//width,height,hints为方法中的参数
           * width the width to which to scale the image.
           * height the height to which to scale the image.
           * hints flags to indicate the type of algorithm to use for image resampling.//指示用于图像重新取样的算法类型的标志，指定缩放的比例算法
           */
          JLabel picJLabel=new JLabel();
          System.out.println(background.getIconHeight() + " " + background.getIconWidth());  
          picJLabel.setBounds(640, 80, 350, 222);
          picJLabel.setIcon(background);
          picJLabel.setHorizontalAlignment(0);  //显示图片的JLabel
          ImageIcon