search
HomeJavajavaTutorialHow to write the code to obtain the local IP address in Java

Preface

How to accurately obtain the local IP address in Java? Most of the methods on the Internet are InetAddress.getLocalHost().getHostAddress(). This can indeed obtain the local IP address, but it is inaccurate. Because one problem has been ignored, the network environment is changeable. Different network cards on a computer have multiple IP addresses, such as Lan, WiFi, Bluetooth, hotspots, virtual machine network cards, etc.

1. Rules

  • 127.xxx.xxx.xxx belongs to the "loopback" address, that is, it can only be seen by your own machine. It is the address of this machine. Compare Common ones are 127.0.0.1

  • 192.168.xxx.xxx, which belongs to the private private address (site local address) and is accessible within the local organization and can only be seen on the local LAN

  • Similarly, 10.xxx.xxx.xxx, from 172.16.xxx.xxx to 172.31.xxx.xxx are all private addresses and belong to internal access of the organization

  • 169.254.xxx.xxx belongs to the link local IP and is available in a single network segment.

  • From 224.xxx.xxx.xxx to 239.xxx.xxx.xxx belongs to the group Broadcast address

  • The special 255.255.255.255 belongs to the broadcast address

  • The other addresses are point-to-point available public IPv4 addresses

2. Obtain

1.Use

 public static void main(String[] args) throws SocketException {
        System.out.println( IpUtil.getLocalIp4Address().get().toString().replaceAll("/",""));
    }

2.Tool class

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));
    }
}

Reference:

https ://www.jianshu.com/p/f619663f0f0a

https://www.cnblogs.com/starcrm/p/7071227.html

The following is a piece of Java to get the local IP Example code for address

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));
    }
}

The above is the detailed content of How to write the code to obtain the local IP address in Java. For more information, please follow other related articles on the PHP Chinese website!

Statement
This article is reproduced at:亿速云. If there is any infringement, please contact admin@php.cn delete
What are the advantages of using bytecode over native code for platform independence?What are the advantages of using bytecode over native code for platform independence?Apr 30, 2025 am 12:24 AM

Bytecodeachievesplatformindependencebybeingexecutedbyavirtualmachine(VM),allowingcodetorunonanyplatformwiththeappropriateVM.Forexample,JavabytecodecanrunonanydevicewithaJVM,enabling"writeonce,runanywhere"functionality.Whilebytecodeoffersenh

Is Java truly 100% platform-independent? Why or why not?Is Java truly 100% platform-independent? Why or why not?Apr 30, 2025 am 12:18 AM

Java cannot achieve 100% platform independence, but its platform independence is implemented through JVM and bytecode to ensure that the code runs on different platforms. Specific implementations include: 1. Compilation into bytecode; 2. Interpretation and execution of JVM; 3. Consistency of the standard library. However, JVM implementation differences, operating system and hardware differences, and compatibility of third-party libraries may affect its platform independence.

How does Java's platform independence support code maintainability?How does Java's platform independence support code maintainability?Apr 30, 2025 am 12:15 AM

Java realizes platform independence through "write once, run everywhere" and improves code maintainability: 1. High code reuse and reduces duplicate development; 2. Low maintenance cost, only one modification is required; 3. High team collaboration efficiency is high, convenient for knowledge sharing.

What are the challenges in creating a JVM for a new platform?What are the challenges in creating a JVM for a new platform?Apr 30, 2025 am 12:15 AM

The main challenges facing creating a JVM on a new platform include hardware compatibility, operating system compatibility, and performance optimization. 1. Hardware compatibility: It is necessary to ensure that the JVM can correctly use the processor instruction set of the new platform, such as RISC-V. 2. Operating system compatibility: The JVM needs to correctly call the system API of the new platform, such as Linux. 3. Performance optimization: Performance testing and tuning are required, and the garbage collection strategy is adjusted to adapt to the memory characteristics of the new platform.

How does the JavaFX library attempt to address platform inconsistencies in GUI development?How does the JavaFX library attempt to address platform inconsistencies in GUI development?Apr 30, 2025 am 12:01 AM

JavaFXeffectivelyaddressesplatforminconsistenciesinGUIdevelopmentbyusingaplatform-agnosticscenegraphandCSSstyling.1)Itabstractsplatformspecificsthroughascenegraph,ensuringconsistentrenderingacrossWindows,macOS,andLinux.2)CSSstylingallowsforfine-tunin

Explain how the JVM acts as an intermediary between the Java code and the underlying operating system.Explain how the JVM acts as an intermediary between the Java code and the underlying operating system.Apr 29, 2025 am 12:23 AM

JVM works by converting Java code into machine code and managing resources. 1) Class loading: Load the .class file into memory. 2) Runtime data area: manage memory area. 3) Execution engine: interpret or compile execution bytecode. 4) Local method interface: interact with the operating system through JNI.

Explain the role of the Java Virtual Machine (JVM) in Java's platform independence.Explain the role of the Java Virtual Machine (JVM) in Java's platform independence.Apr 29, 2025 am 12:21 AM

JVM enables Java to run across platforms. 1) JVM loads, validates and executes bytecode. 2) JVM's work includes class loading, bytecode verification, interpretation execution and memory management. 3) JVM supports advanced features such as dynamic class loading and reflection.

What steps would you take to ensure a Java application runs correctly on different operating systems?What steps would you take to ensure a Java application runs correctly on different operating systems?Apr 29, 2025 am 12:11 AM

Java applications can run on different operating systems through the following steps: 1) Use File or Paths class to process file paths; 2) Set and obtain environment variables through System.getenv(); 3) Use Maven or Gradle to manage dependencies and test. Java's cross-platform capabilities rely on the JVM's abstraction layer, but still require manual handling of certain operating system-specific features.

See all articles

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

Dreamweaver Mac version

Dreamweaver Mac version

Visual web development tools

SublimeText3 English version

SublimeText3 English version

Recommended: Win version, supports code prompts!

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

VSCode Windows 64-bit Download

VSCode Windows 64-bit Download

A free and powerful IDE editor launched by Microsoft

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment