这是我的代码
public static String getRealIp() throws SocketException {
String localip = null;// 本地IP，如果没有配置外网IP则返回它
String netip = null;// 外网IP

        Enumeration<NetworkInterface> netInterfaces =
            NetworkInterface.getNetworkInterfaces();
        InetAddress ip = null;
        boolean finded = false;// 是否找到外网IP
        while (netInterfaces.hasMoreElements() && !finded) {
            NetworkInterface ni = netInterfaces.nextElement();
            Enumeration<InetAddress> address = ni.getInetAddresses();
            while (address.hasMoreElements()) {
                ip = address.nextElement();
                if (!ip.isSiteLocalAddress()
                        && !ip.isLoopbackAddress()
                        && ip.getHostAddress().indexOf(":") == -1) {// 外网IP
                    netip = ip.getHostAddress();
                    finded = true;
                    break;
                } else if (ip.isSiteLocalAddress()
                        && !ip.isLoopbackAddress()
                        && ip.getHostAddress().indexOf(":") == -1) {// 内网IP
                    localip = ip.getHostAddress();
                }
            }
        }

        if (netip != null && !"".equals(netip)) {
            return netip;
        } else {
            return localip;
        }
    }