Analysis on the problem of J2SE path

public void init(){
//获取资源相对路径(由于java会使用绝对路径来找资源,打成jar时,资源便找不到,所以)
Image image=Toolkit.getDefaultToolkit().getImage(getClass().getResource("a.gif"));
ImageIcon icon=new ImageIcon(image);
bt.setIcon(icon);
String cName= this.getClass().getName();
System.out.println(cName);
this.add(bt);
this.setSize(300, 300);
setVisible(true);
this.addWindowListener(new WindowAdapter(){ @Override
public void windowClosing(WindowEvent e) {
// TODO Auto-generated method stub
super.windowClosing(e);
System.exit(0);
}
});
}