java写个util,获取本机ip,并使用Google Guava 缓存起来
四个方法:

• 获取本机ipv4
• ip转16进制
• 16进制转ip
• 校验ip

首先,Google Guava使用的maven配置

		<dependency><groupId>com.google.guava</groupId><artifactId>guava</artifactId><version>18.6.1.8</version></dependency>

import com.google.common.cache.Cache;
import com.google.common.cache.CacheBuilder;
import java.net.Inet4Address;
import java.net.InetAddress;
import java.net.NetworkInterface;
import java.util.Enumeration;
import java.util.concurrent.Callable;
import java.util.concurrent.TimeUnit;public class MyUtil {//使用缓存private static Cache<String, String> cache = CacheBuilder.newBuilder().maximumSize(1).expireAfterWrite(2, TimeUnit.DAYS).build();/*** 获取本机ipv4地址, 当机器有多张网卡时，只会获取其中一个* 默认会缓存2天*/public static String getIpv4() throws Exception {return cache.get("ip", new Callable<String>() {@Overridepublic String call() throws Exception {Enumeration<NetworkInterface> nis = NetworkInterface.getNetworkInterfaces();while (nis.hasMoreElements()) {NetworkInterface ni = nis.nextElement();if (!ni.isUp() || ni.isLoopback() || ni.isVirtual()) {continue;}Enumeration<InetAddress> ias = ni.getInetAddresses();if (!ias.hasMoreElements()) {continue;}while (ias.hasMoreElements()) {InetAddress ia = ias.nextElement();if (ia.isLoopbackAddress()) {continue;}if (!(ia instanceof Inet4Address)) {continue;}return ia.getHostAddress();}}return "";}});}/*** 判断是否是合法的ipv4地址* @param ipStr* @return*/public static boolean isIpV4(String ipStr){if (ipStr != null && !ipStr.isEmpty()) {String regex="^(((\\d{1,2})|(1\\d{2})|(2[0-4]\\d)|(25[0-5]))\\.){3}((\\d{1,2})|(1\\d{2})|(2[0-4]\\d)|(25[0-5]))$";if (ipStr.matches(regex)) {return true;} else {return false;}}return false;}/*** 将ip转换为定长8个字符的16进制表示形式：255.255.255.255 -> FFFFFFFF* @param ip  ipv4地址* @return String hex表示的ipv4地址*/public static String hexIp(String ip) {StringBuilder sb = new StringBuilder();for (String seg : ip.split(IP_SPLIT)) {String h = Integer.toHexString(Integer.parseInt(seg));if (h.length() == 1) {sb.append("0");}sb.append(h);}return sb.toString();}/*** 将16进制表示的ip地址转换为数字表示形式： FFFFFFFF -> 255.255.255.255* @param hexIp  hex表示的ipv4地址* @return String 数字表示ipv4地址*/public static String hexIpToString(String hexIp){StringBuilder sb = new StringBuilder();int i = 0;StringBuffer tmp = new StringBuffer();int len = hexIp.toCharArray().length;for (char seg : hexIp.toCharArray()) {tmp.append(seg);i++;if(i % 2 == 0){int val = Integer.parseInt(tmp.toString(), 16);sb.append(val);if(i < len){sb.append(".");}tmp = new StringBuffer();}}return sb.toString();}public static void main(String[] args) throws Exception {//测试String ipv4 = getIpv4();System.out.println("ip:"+ipv4);String s16 = hexIp(ipv4);System.out.println("16进制ip:"+s16);String s10 = hexIpToString(s16);System.out.println("10进制ip:"+s10);boolean isOk = isIpV4(ipv4);System.out.println("是否是有效ip:"+isOk );}
}