Java:判断当前操作系统界面采用的主题是windows经典样式还是xp样式

/** Get the singleton instance of this class
      *
      * @return the singleton instance of this class or null if XP styles
      * are not active or if this is not Windows XP
      */
     static synchronized XPStyle getXP() {
         if (themeActive == null) {
             Toolkit toolkit = Toolkit.getDefaultToolkit();
             themeActive =
                 (Boolean)toolkit.getDesktopProperty("win.xpstyle.themeActive");
             if (themeActive == null) {
                 themeActive = Boolean.FALSE;
             }
             if (themeActive.booleanValue()) {
                 GetPropertyAction propertyAction =
                     new GetPropertyAction("swing.noxp");
                 if (AccessController.doPrivileged(propertyAction) == null &&
                     ThemeReader.isThemed() &&
                     !(UIManager.getLookAndFeel()
                       instanceof WindowsClassicLookAndFeel)) {

                     xp = new XPStyle();
                 }
             }
         }
         return xp;
     }