设置Swing使用系统风格的组件

      private void setLookFeel() {
          try {

             // Set System L&F
             UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
          }
          catch (Exception e) {
             System.out.println("Cannot set System look and feel. Default look and feel will be used.");
          }
      }