Java can obtain IP address (windos, linux)

package com.teamdev.jxbrowser.chromium.demo.getLocalIp;

import java.net.InetAddress;
import java.net.NetworkInterface;
import java.net.SocketException;
import java.net.UnknownHostException;
import java.util.Enumeration;

public class getServerIp {
/**
* Get the server ip address
* */
public static String getServerIp() {
        // Get the operating system type
        String sysType = System.getProperties().getProperty("os.name");
        System.out.println( sysType);
        String ip;
        if (sysType.toLowerCase().startsWith("win")) {// If it is a Windows system, get the local IP address
            String localIP = null;
            try {
                localIP = InetAddress.getLocalHost().getHostAddress();
            } catch (UnknownHostException e) {
            e.printStackTrace();
            }
            if (localIP != null) {
                return localIP;
            }
        } else {
            ip = getIpByEthNum("eth0"); //Compatible with Linux
            if (ip != null) {
                return ip;
            }
        }
        return "Error getting server IP";
    }
/**
     * Get IP address according to network interface
     * @param ethNum network interface name, eth0 under Linux
     * @ return
     */
    private static String getIpByEthNum(String ethNum) {
        try {
            Enumeration allNetInterfaces = NetworkInterface.getNetworkInterfaces();
            InetAddress ip;
            while (allNetInterfaces.hasMoreElements()) {
                NetworkInterface netInterface = (NetworkInterface) allNetInterfaces.nextElement();
                if (ethNum.equals(netInterface.getName())) {
                    Enumeration addresses = netInterface.getInetAddresses();
                    while (addresses.hasMoreElements()) {
                        ip = (InetAddress) addresses.nextElement();
                        if (ip != null) {
                            return ip.getHostAddress();
                        }
                    }
                }
            }
        } catch (SocketException e) {
            e.printStackTrace();
        }
        return "获取服务器IP错误";
    }
public static void main(String[] args) {
try {
System.out.println(getServerIp());
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}