在线求教：如何得知运行applet的浏览器被强行关闭

Question

addWindowListener(new WindowAdapter()
       {
           public void windowCloseing(WindowEvent ex)
           {
               System.out.println("windowCloseing:"+ex);
               getInstance(); //get event form here
               System.exit(0);
               //con=getContentPanel
           }
       });
        public void getInstance(){
          ...
        }