首先，你如果搜索“JAVA获取本机IP地址”，基本上搜到的资料全是无用的。
比如这篇：http://www.cnblogs.com/zrui-xyu/p/5039551.html
实际上的代码在复杂环境下是不准的
网上一个比较普遍的说法是InetAddress.getLocalHost().getHostAddress()
似乎很简单，但忽略了一个问题，即IP地址在现在的网络环境更加复杂了，比如有Lan，WIFI，蓝牙热点，虚拟机网卡...
即存在很多的网络接口（network interfaces），每个网络接口就包含一个IP地址，并不是所有的IP地址能被外部或局域网访问，比如说虚拟机网卡地址等等。
也就是说InetAddress.getLocalHost().getHostAddress()的IP不一定是正确的IP。
写代码前，先明确一些规则：
- 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
- 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
获取本机IP地址的正确姿势：
package ipTest; import java.net.Inet4Address;
import java.net.InetAddress;
import java.net.NetworkInterface;
import java.net.SocketException;
import java.net.UnknownHostException;
import java.util.Enumeration; public class Test { public Test() {
// TODO Auto-generated constructor stub
} public static void main(String[] args) {
// TODO Auto-generated method stub
InetAddress ip;
try {
// 这种IP容易拿错
// System.out.println("Current IP address : " +
// InetAddress.getLocalHost().getHostAddress());
// 不一定准确的IP拿法
// 出自比如这篇：http://www.cnblogs.com/zrui-xyu/p/5039551.html
System.out.println("get LocalHost Address : " + getLocalHostAddress().getHostAddress()); // 正确的IP拿法
System.out.println("get LocalHost LAN Address : " + getLocalHostLANAddress().getHostAddress()); } catch (UnknownHostException e) { e.printStackTrace(); }
} // 正确的IP拿法，即优先拿site-local地址
private static InetAddress getLocalHostLANAddress() throws UnknownHostException {
try {
InetAddress candidateAddress = null;
// 遍历所有的网络接口
for (Enumeration ifaces = NetworkInterface.getNetworkInterfaces(); ifaces.hasMoreElements();) {
NetworkInterface iface = (NetworkInterface) ifaces.nextElement();
// 在所有的接口下再遍历IP
for (Enumeration inetAddrs = iface.getInetAddresses(); inetAddrs.hasMoreElements();) {
InetAddress inetAddr = (InetAddress) inetAddrs.nextElement();
if (!inetAddr.isLoopbackAddress()) {// 排除loopback类型地址
if (inetAddr.isSiteLocalAddress()) {
// 如果是site-local地址，就是它了
return inetAddr;
} else if (candidateAddress == null) {
// site-local类型的地址未被发现，先记录候选地址
candidateAddress = inetAddr;
}
}
}
}
if (candidateAddress != null) {
return candidateAddress;
}
// 如果没有发现 non-loopback地址.只能用最次选的方案
InetAddress jdkSuppliedAddress = InetAddress.getLocalHost();
if (jdkSuppliedAddress == null) {
throw new UnknownHostException("The JDK InetAddress.getLocalHost() method unexpectedly returned null.");
}
return jdkSuppliedAddress;
} catch (Exception e) {
UnknownHostException unknownHostException = new UnknownHostException(
"Failed to determine LAN address: " + e);
unknownHostException.initCause(e);
throw unknownHostException;
}
} //出自这篇：http://www.cnblogs.com/zrui-xyu/p/5039551.html
//实际上的代码是不准的
private static InetAddress getLocalHostAddress() throws UnknownHostException {
Enumeration allNetInterfaces;
try {
allNetInterfaces = NetworkInterface.getNetworkInterfaces();
InetAddress ip = null;
while (allNetInterfaces.hasMoreElements()) {
NetworkInterface netInterface = (NetworkInterface) allNetInterfaces.nextElement(); Enumeration addresses = netInterface.getInetAddresses();
while (addresses.hasMoreElements()) {
ip = (InetAddress) addresses.nextElement();
if (!ip.isSiteLocalAddress() && !ip.isLoopbackAddress() && ip.getHostAddress().indexOf(":") == -1) {
if (ip != null && ip instanceof Inet4Address) {
return ip;
}
}
}
}
} catch (SocketException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} InetAddress jdkSuppliedAddress = InetAddress.getLocalHost();
if (jdkSuppliedAddress == null) {
throw new UnknownHostException("The JDK InetAddress.getLocalHost() method unexpectedly returned null.");
}
return jdkSuppliedAddress;
} }