问Java中如何以编程方式确定操作系统？

public static final class OsUtils

{

   private static String OS = null;

   public static String getOsName()

   {

      if(OS == null) { OS = System.getProperty("os.name"); }

      return OS;

   }

   public static boolean isWindows()

   {

      return getOsName().startsWith("Windows");

   }

   public static boolean isUnix() // and so on

}

System.getProperty("os.name")

class ShowProperties {

    public static void main(String[] args) {

        System.getProperties().list(System.out);

    }

}