可以给JPanel增加事件吗，我已子类化

Question

public class MyJPanel
    extends JPanel
    implements  WindowListener {  public MyJPanel() {  }
  public void windowOpened(WindowEvent e) {
    // TODO: Add your code here
    JOptionPane.showMessageDialog(null,
                                  "windowOpened！",
                                  "系统提示", JOptionPane.INFORMATION_MESSAGE);
  }
}但windowOpened　没有调用，