public static String ipYuMsk(InetAddress ip)
    {
        
        byte[] b=ip.getAddress();
        long l= b[0]<<24L & 0xff000000L|
                b[1]<<16L & 0xff0000L  |
                b[2]<<8L  &  0xff00L   |
                b[3]<<0L  &  0xffL ;
        
        return Integer.toBinaryString((int)l);
    }这段代码可以实现