前言
在java中如何准确的获取到本机ip地址呢？网上大部分的做法是inetaddress.getlocalhost().gethostaddress()。这的确能获取到本机ip地址，但是是不准确的。因为忽略了一个问题，网络环境是多变的，一台计算机不同的网卡有多个ip地址，lan、wifi、蓝牙、热点、虚拟机网卡等。
一、规则
127.xxx.xxx.xxx 属于 “loopback” 地址，即只能你自己的本机可见，就是本机地址，比较常见的有 127.0.0.1
192.168.xxx.xxx 属于 private 私有地址 (site local address)，属于本地组织内部访问，只能在本地局域网可见
同样 10.xxx.xxx.xxx、从 172.16.xxx.xxx 到172.31.xxx.xxx 都是私有地址，也是属于组织内部访问
-
169.254.xxx.xxx 属于连接本地地址（link local IP），在单独网段可用
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从 224.xxx.xxx.xxx 到 239.xxx.xxx.xxx 属于组播地址
比较特殊的 255.255.255.255 属于广播地址
除此之外的地址就是点对点的可用的公开 IPv4 地址
二、获取
1.使用
public static void main(String[] args) throws SocketException {
System.out.println( IpUtil.getLocalIp4Address().get().toString().replaceAll("/",""));
}2.工具类
package com.dingwen.test.utils;
import org.springframework.util.ObjectUtils;
import java.net.*;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;
import java.util.Optional;
/**
* 获取本机IP 地址
*
* @author dingwen
* 2021.04.28 11:49
*/
public class IpUtil {
/*
* 获取本机所有网卡信息 得到所有IP信息
* @return Inet4Address>
*/
public static List<Inet4Address> getLocalIp4AddressFromNetworkInterface() throws SocketException {
List<Inet4Address> addresses = new ArrayList<>(1);
// 所有网络接口信息
Enumeration<NetworkInterface> networkInterfaces = NetworkInterface.getNetworkInterfaces();
if (ObjectUtils.isEmpty(networkInterfaces)) {
return addresses;
}
while (networkInterfaces.hasMoreElements()) {
NetworkInterface networkInterface = networkInterfaces.nextElement();
//滤回环网卡、点对点网卡、非活动网卡、虚拟网卡并要求网卡名字是eth或ens开头
if (!isValidInterface(networkInterface)) {
continue;
}
// 所有网络接口的IP地址信息
Enumeration<InetAddress> inetAddresses = networkInterface.getInetAddresses();
while (inetAddresses.hasMoreElements()) {
InetAddress inetAddress = inetAddresses.nextElement();
// 判断是否是IPv4，并且内网地址并过滤回环地址.
if (isValidAddress(inetAddress)) {
addresses.add((Inet4Address) inetAddress);
}
}
}
return addresses;
}
/**
* 过滤回环网卡、点对点网卡、非活动网卡、虚拟网卡并要求网卡名字是eth或ens开头
*
* @param ni 网卡
* @return 如果满足要求则true，否则false
*/
private static boolean isValidInterface(NetworkInterface ni) throws SocketException {
return !ni.isLoopback() && !ni.isPointToPoint() && ni.isUp() && !ni.isVirtual()
&& (ni.getName().startsWith("eth") || ni.getName().startsWith("ens"));
}
/**
* 判断是否是IPv4，并且内网地址并过滤回环地址.
*/
private static boolean isValidAddress(InetAddress address) {
return address instanceof Inet4Address && address.isSiteLocalAddress() && !address.isLoopbackAddress();
}
/*
* 通过Socket 唯一确定一个IP
* 当有多个网卡的时候，使用这种方式一般都可以得到想要的IP。甚至不要求外网地址8.8.8.8是可连通的
* @return Inet4Address>
*/
private static Optional<Inet4Address> getIpBySocket() throws SocketException {
try (final DatagramSocket socket = new DatagramSocket()) {
socket.connect(InetAddress.getByName("8.8.8.8"), 10002);
if (socket.getLocalAddress() instanceof Inet4Address) {
return Optional.of((Inet4Address) socket.getLocalAddress());
}
} catch (UnknownHostException networkInterfaces) {
throw new RuntimeException(networkInterfaces);
}
return Optional.empty();
}
/*
* 获取本地IPv4地址
* @return Inet4Address>
*/
public static Optional<Inet4Address> getLocalIp4Address() throws SocketException {
final List<Inet4Address> inet4Addresses = getLocalIp4AddressFromNetworkInterface();
if (inet4Addresses.size() != 1) {
final Optional<Inet4Address> ipBySocketOpt = getIpBySocket();
if (ipBySocketOpt.isPresent()) {
return ipBySocketOpt;
} else {
return inet4Addresses.isEmpty() ? Optional.empty() : Optional.of(inet4Addresses.get(0));
}
}
return Optional.of(inet4Addresses.get(0));
}
}参考：
https://www.jianshu.com/p/f619663f0f0a
https://www.cnblogs.com/starcrm/p/7071227.html
下面在分享一段Java获取本机IP地址的示例代码
import java.net.*;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;
import java.util.Objects;
import java.util.Optional;
/**
* 获取本机IP 地址
*/
public class IpUtil {
/*
* 获取本机所有网卡信息 得到所有IP信息
* @return Inet4Address>
*/
public static List<Inet4Address> getLocalIp4AddressFromNetworkInterface() throws SocketException {
List<Inet4Address> addresses = new ArrayList<>(1);
// 所有网络接口信息
Enumeration<NetworkInterface> networkInterfaces = NetworkInterface.getNetworkInterfaces();
if (Objects.isNull(networkInterfaces)) {
return addresses;
}
while (networkInterfaces.hasMoreElements()) {
NetworkInterface networkInterface = networkInterfaces.nextElement();
//滤回环网卡、点对点网卡、非活动网卡、虚拟网卡并要求网卡名字是eth或ens开头
if (!isValidInterface(networkInterface)) {
continue;
}
// 所有网络接口的IP地址信息
Enumeration<InetAddress> inetAddresses = networkInterface.getInetAddresses();
while (inetAddresses.hasMoreElements()) {
InetAddress inetAddress = inetAddresses.nextElement();
// 判断是否是IPv4，并且内网地址并过滤回环地址.
if (isValidAddress(inetAddress)) {
addresses.add((Inet4Address) inetAddress);
}
}
}
return addresses;
}
/**
* 过滤回环网卡、点对点网卡、非活动网卡、虚拟网卡并要求网卡名字是eth或ens开头
*
* @param ni 网卡
* @return 如果满足要求则true，否则false
*/
private static boolean isValidInterface(NetworkInterface ni) throws SocketException {
return !ni.isLoopback() && !ni.isPointToPoint() && ni.isUp() && !ni.isVirtual()
&& (ni.getName().startsWith("eth") || ni.getName().startsWith("ens"));
}
/**
* 判断是否是IPv4，并且内网地址并过滤回环地址.
*/
private static boolean isValidAddress(InetAddress address) {
return address instanceof Inet4Address && address.isSiteLocalAddress() && !address.isLoopbackAddress();
}
/*
* 通过Socket 唯一确定一个IP
* 当有多个网卡的时候，使用这种方式一般都可以得到想要的IP。甚至不要求外网地址8.8.8.8是可连通的
* @return Inet4Address>
*/
private static Optional<Inet4Address> getIpBySocket() throws SocketException {
try (final DatagramSocket socket = new DatagramSocket()) {
socket.connect(InetAddress.getByName("8.8.8.8"), 10002);
if (socket.getLocalAddress() instanceof Inet4Address) {
return Optional.of((Inet4Address) socket.getLocalAddress());
}
} catch (UnknownHostException networkInterfaces) {
throw new RuntimeException(networkInterfaces);
}
return Optional.empty();
}
/*
* 获取本地IPv4地址
* @return Inet4Address>
*/
public static Optional<Inet4Address> getLocalIp4Address() throws SocketException {
final List<Inet4Address> inet4Addresses = getLocalIp4AddressFromNetworkInterface();
if (inet4Addresses.size() != 1) {
final Optional<Inet4Address> ipBySocketOpt = getIpBySocket();
if (ipBySocketOpt.isPresent()) {
return ipBySocketOpt;
} else {
return inet4Addresses.isEmpty() ? Optional.empty() : Optional.of(inet4Addresses.get(0));
}
}
return Optional.of(inet4Addresses.get(0));
}
} 
