java获取路由器ip

要获取路由器的IP地址，需要使用Java中的网络编程API，可以通过以下步骤来实现：

1. 获取本机的IP地址
可以使用Java中的InetAddress类的getLocalHost()方法来获取本机的IP地址，如下所示：

InetAddress localHost = InetAddress.getLocalHost();
String ipAddress = localHost.getHostAddress();

2. 通过IP地址获取网络接口
可以使用NetworkInterface类的getByInetAddress()方法，通过本机的IP地址获取对应的网络接口，如下所示：

NetworkInterface networkInterface = NetworkInterface.getByInetAddress(localHost);

3. 获取路由器的IP地址
使用网络接口的getInterfaceAddresses()方法获取接口的地址列表，然后遍历列表，找到类型为INET4（IPv4）的地址，获取其子网掩码，通过子网掩码可以计算出路由器的IP地址，如下所示：

List<InterfaceAddress> interfaceAddresses = networkInterface.getInterfaceAddresses();
for (InterfaceAddress interfaceAddress : interfaceAddresses) {
    InetAddress inetAddress = interfaceAddress.getAddress();
    if (inetAddress instanceof Inet4Address && !inetAddress.isLoopbackAddress()) {
        int prefixLength = interfaceAddress.getNetworkPrefixLength();
        String subnetMask = getSubnetMask(prefixLength);
        String[] subnetMaskParts = subnetMask.split("\\.");
        String[] ipAddressParts = ipAddress.split("\\.");
        StringBuilder routerIpAddress = new StringBuilder();
        for (int i = 0; i < 4; i++) {
            int routerIpPart = Integer.parseInt(ipAddressParts[i]) & Integer.parseInt(subnetMaskParts[i]);
            routerIpAddress.append(routerIpPart);
            if (i < 3) {
                routerIpAddress.append(".");
            }
        }
        System.out.println("Router IP Address: " + routerIpAddress.toString());
        break;
    }
}

其中，getSubnetMask()方法用于计算子网掩码，实现如下所示：

private static String getSubnetMask(int prefixLength) {
    int mask = 0xffffffff << (32 - prefixLength);
    byte[] bytes = new byte[] {
            (byte) (mask >>> 24 & 0xff),
            (byte) (mask >>> 16 & 0xff),
            (byte) (mask >>> 8 & 0xff),
            (byte) (mask & 0xff)
    };
    try {
        InetAddress inetAddress = InetAddress.getByAddress(bytes);
        return inetAddress.getHostAddress();
    } catch (UnknownHostException e) {
        e.printStackTrace();
    }
    return null;
}

这样就可以获取到路由器的IP地址了。