my_wifiManager = ((WifiManager) getApplicationContext().getSystemService(WIFI_SERVICE));
            assert my_wifiManager != null;
            dhcpInfo = my_wifiManager.getDhcpInfo();

解析方法 

    public static InetAddress intToInetAddress(int hostAddress) {
        byte[] addressBytes = {(byte) (0xff & hostAddress),
                (byte) (0xff & (hostAddress >> 8)),
                (byte) (0xff & (hostAddress >> 16)),
                (byte) (0xff & (hostAddress >> 24))};

        try {
            return InetAddress.getByAddress(addressBytes);
        } catch (UnknownHostException e) {
            throw new AssertionError();
        }
    }

获取方式 

intToInetAddress(dhcpInfo.gateway).getHostAddress()